Report 137
Silicone Elastomers
P. Jerschow
Volume 12, Number 5, 2001
RAPRA REVIEW REPORTS A Rapra Review Report comprises three sections, as follows: 1. A commissioned expert review, discussing a key topic of current interest, and referring to the References and Abstracts section. Reference numbers in brackets refer to item numbers from the References and Abstracts section. Where it has been necessary for completeness to cite sources outside the scope of the Rapra Abstracts database, these are listed at the end of the review, and cited in the text as a.1, a.2, etc. 2. A comprehensive References and Abstracts section, resulting from a search of the Rapra Abstracts database. The format of the abstracts is outlined in the sample record below. 3. An index to the References and Abstracts section, derived from the indexing terms which are added to the abstracts records on the database to aid retrieval.
Source of original article Title
Item 1 Macromolecules
33, No.6, 21st March 2000, p.2171-83 EFFECT OF THERMAL HISTORY ON THE RHEOLOGICAL BEHAVIOR OF THERMOPLASTIC POLYURETHANES Pil Joong Yoon; Chang Dae Han Akron,University The effect of thermal history on the rheological behaviour of ester- and ether-based commercial thermoplastic PUs (Estane 5701, 5707 and 5714 from B.F.Goodrich) was investigated. It was found that the injection moulding temp. used for specimen preparation had a marked effect on the variations of dynamic storage and loss moduli of specimens with time observed during isothermal annealing. Analysis of FTIR spectra indicated that variations in hydrogen bonding with time during isothermal annealing very much resembled variations of dynamic storage modulus with time during isothermal annealing. Isochronal dynamic temp. sweep experiments indicated that the thermoplastic PUs exhibited a hysteresis effect in the heating and cooling processes. It was concluded that the microphase separation transition or order-disorder transition in thermoplastic PUs could not be determined from the isochronal dynamic temp. sweep experiment. The plots of log dynamic storage modulus versus log loss modulus varied with temp. over the entire range of temps. (110-190C) investigated. 57 refs.
Location
GOODRICH B.F. USA
Authors and affiliation
Abstract
Companies or organisations mentioned
Accession no.771897
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Advanced Composites, D.K. Thomas, RAE, Farnborough.
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Failure of Plastics, S. Turner, Queen Mary College.
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Report 49
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Report 60
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Food Contact Polymeric Materials, J.A. Sidwell, Rapra Technology Ltd.
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Report 62
Coextrusion, D. Djordjevic, Klöckner ER-WE-PA GmbH.
Report 63
Conductive Polymers II, R.H. Friend, University of Cambridge, Cavendish Laboratory.
Report 64
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Report 32
Fluoroelastomers - Properties and Applications, D. Cook and M. Lynn, 3M United Kingdom Plc and 3M Belgium SA.
Report 33
Polyamides, R.S. Williams and T. Daniels, T & N Technology Ltd. and BIP Chemicals Ltd.
Report 65
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Extrusion of Rubber, J.G.A. Lovegrove, Nova Petrochemicals Inc.
Report 66
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Polymers in Household Electrical Goods, D.Alvey, Hotpoint Ltd.
Reinforced Thermoplastics - Composition, Processing and Applications, P.G. Kelleher, New Jersey Polymer Extension Center at Stevens Institute of Technology.
Report 67
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Developments in Additives to Meet Health and Environmental Concerns, M.J. Forrest, Rapra Technology Ltd.
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Report 68
Cure Assessment by Physical and Chemical Techniques, B.G. Willoughby, Rapra Technology Ltd.
Report 69
Toxicity of Plastics and Rubber in Fire, P.J. Fardell, Building Research Establishment, Fire Research Station.
Report 70
Acrylonitrile-Butadiene-Styrene Polymers, M.E. Adams, D.J. Buckley, R.E. Colborn, W.P. England and D.N. Schissel, General Electric Corporate Research and Development Center.
Report 71
Rotational Moulding, R.J. Crawford, The Queen’s University of Belfast.
Report 72
Advances in Injection Moulding, C.A. Maier, Econology Ltd.
Report 94
Compressive Behaviour of Composites, C. Soutis, Imperial College of Science, Technology and Medicine.
Report 95
Thermal Analysis of Polymers, M. P. Sepe, Dickten & Masch Manufacturing Co.
Report 96
Polymeric Seals and Sealing Technology, J.A. Hickman, St Clair (Polymers) Ltd.
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Rubber Compounding Ingredients - Need, Theory and Innovation, Part II: Processing, Bonding, Fire Retardants, C. Hepburn, University of Ulster.
Report 98
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Report 99
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Report 74
Speciality Rubbers, J.A. Brydson.
Report 75
Plastics and the Environment, I. Boustead, Boustead Consulting Ltd.
Report 100 Photoinitiated Polymerisation - Theory and Applications, J.P. Fouassier, Ecole Nationale Supérieure de Chimie, Mulhouse.
Report 76
Polymeric Precursors for Ceramic Materials, R.C.P. Cubbon.
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Report 78
PVC - Compounds, Processing and Applications, J.Leadbitter, J.A. Day, J.L. Ryan, Hydro Polymers Ltd.
Report 103
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Rubber Compounding Ingredients - Need, Theory and Innovation, Part I: Vulcanising Systems, Antidegradants and Particulate Fillers for General Purpose Rubbers, C. Hepburn, University of Ulster.
Report 80
Anti-Corrosion Polymers: PEEK, PEKK and Other Polyaryls, G. Pritchard, Kingston University.
Report 81
Thermoplastic Elastomers - Properties and Applications, J.A. Brydson.
Report 82
Advances in Blow Moulding Process Optimization, Andres Garcia-Rejon,Industrial Materials Institute, National Research Council Canada.
Report 83
Molecular Weight Characterisation of Synthetic Polymers, S.R. Holding and E. Meehan, Rapra Technology Ltd. and Polymer Laboratories Ltd.
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Rheology and its Role in Plastics Processing, P. Prentice, The Nottingham Trent University.
Gas Assisted Moulding, T.C. Pearson, Gas Injection Ltd.
Report 104 Plastics Profile Extrusion, R.J. Kent, Tangram Technology Ltd. Report 105 Rubber Extrusion Theory and Development, B.G. Crowther. Report 106 Properties and Applications of Elastomeric Polysulfides, T.C.P. Lee, Oxford Brookes University. Report 107 High Performance Polymer Fibres, P.R. Lewis, The Open University. Report 108 Chemical Characterisation of Polyurethanes, M.J. Forrest, Rapra Technology Ltd.
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Report 111
Polymer Product Failure, P.R. Lewis, The Open University.
Report 85
Ring Opening Polymerisation, N. Spassky, Université Pierre et Marie Curie.
Report 112 Polystyrene - Synthesis, Production and Applications, J.R. Wünsch, BASF AG.
Report 86
High Performance Engineering Plastics, D.J. Kemmish, Victrex Ltd.
Report 113 Rubber-Modified Thermoplastics, H. Keskkula, University of Texas at Austin.
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Rubber to Metal Bonding, B.G. Crowther, Rapra Technology Ltd.
Report 114 Developments in Polyacetylene - Nanopolyacetylene, V.M. Kobryanskii, Russian Academy of Sciences.
Report 88
Plasticisers - Selection, Applications and Implications, A.S. Wilson.
Report 115 Metallocene-Catalysed Polymerisation, W. Kaminsky, University of Hamburg.
Report 89
Polymer Membranes - Materials, Structures and Separation Performance, T. deV. Naylor, The Smart Chemical Company.
Report 116 Compounding in Co-rotating Twin-Screw Extruders, Y. Wang, Tunghai University.
Report 90
Rubber Mixing, P.R. Wood.
Report 117 Rapid Prototyping, Tooling and Manufacturing, R.J.M. Hague and P.E. Reeves, Edward Mackenzie Consulting.
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Recent Developments in Epoxy Resins, I. Hamerton, University of Surrey.
Report 118 Liquid Crystal Polymers - Synthesis, Properties and Applications, D. Coates, CRL Ltd.
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Continuous Vulcanisation of Elastomer Profiles, A. Hill, Meteor Gummiwerke.
Report 119 Rubbers in Contact with Food, M.J. Forrest and J.A. Sidwell, Rapra Technology Ltd.
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Advances in Thermoforming, J.L. Throne, Sherwood Technologies Inc.
Report 120 Electronics Applications of Polymers II, M.T. Goosey, Shipley Ronal.
Report 126 Composites for Automotive Applications, C.D. Rudd, University of Nottingham.
Volume 11 Report 121 Polyamides as Engineering Thermoplastic Materials, I.B. Page, BIP Ltd. Report 122 Flexible Packaging - Adhesives, Coatings and Processes, T.E. Rolando, H.B. Fuller Company. Report 123 Polymer Blends, L.A. Utracki, National Research Council Canada. Report 124 Sorting of Waste Plastics for Recycling, R.D. Pascoe, University of Exeter. Report 125 Structural Studies of Polymers by Solution NMR, H.N. Cheng, Hercules Incorporated.
Report 127 Polymers in Medical Applications, B.J. Lambert and F.-W. Tang, Guidant Corp., and W.J. Rogers, Consultant. Report 128 Solid State NMR of Polymers, P.A. Mirau, Lucent Technologies. Report 129 Failure of Polymer Products Due to Photo-oxidation, D.C. Wright. Report 130 Failure of Polymer Products Due to Chemical Attack, D.C. Wright. Report 131 Failure of Polymer Products Due to Thermo-oxidation, D.C. Wright. Report 132 Stabilisers for Polyolefins, C. Kröhnke and F. Werner, Clariant Huningue SA.
Titles Available in the Current Volume Volume 12 Report 133 Advances in Automation for Plastics Injection Moulding, J. Mallon, Yushin Inc. Report 134 Infrared and Raman Spectroscopy of Polymers, J.L. Koenig, Case Western Reserve University. Report 135 Polymers in Sport and Leisure, R.P. Brown. Report 136 Radiation Curing, R.S. Davidson, DavRad Services. Report 137 Silicone Elastomers, P. Jerschow, Wacker-Chemie GmbH. Report 138 Health and Safety in the Rubber Industry, N. Chaiear, Khon Kaen University. Report 139 Rubber Analysis - Polymers, Compounds and Products, M.J. Forrest, Rapra Technology Ltd.
Silicone Elastomers
Peter Jerschow (Wacker-Chemie GmbH)
ISBN: 1-85957-297-9
Silicone Elastomers
Contents 1.
Introduction .............................................................................................................................................. 5 1.1 Nomenclature....................................................................................................................................... 5
2.
Silicone Elastomers Market .................................................................................................................... 6
3.
Applications for Silicone Elastomers ..................................................................................................... 7
4.
5.
3.1
Automotive ..................................................................................................................................... 7
3.2
Healthcare and Medical .................................................................................................................. 9
3.3
Wire and Cable ..............................................................................................................................11
3.4
Sanitary, Household and Leisure .................................................................................................. 13
3.5
Transmission and Distribution ...................................................................................................... 16
3.6
Electronics .................................................................................................................................... 17
3.7
Mould Making .............................................................................................................................. 20
3.8
Food Sector ................................................................................................................................... 21
3.9
Other 3.9.1 3.9.2 3.9.3 3.9.4 3.9.5
............................................................................................................................................. 23 Safety Applications ........................................................................................................... 23 Aerospace ......................................................................................................................... 24 Building Industry .............................................................................................................. 24 Pharmaceutical ................................................................................................................. 24 Spin Casting...................................................................................................................... 24
Composition and Function of Silicone Elastomers............................................................................. 25 4.1
Introduction and Classifications ................................................................................................... 25
4.2
Properties of Silicone Elastomers ................................................................................................. 25
4.3
Chemistry and Curing Mechanisms of Silicone Elastomers ........................................................ 26
Room Temperature Vulcanising Silicone Elastomers ........................................................................ 27 5.1
General .......................................................................................................................................... 27
5.2
Condensation Curing RTVs .......................................................................................................... 28
5.3
RTV-1 for CIPG and FIPG ........................................................................................................... 28
5.4
RTV-1 for Baking Tray Coatings .................................................................................................. 29
5.5
Adhesive RTV-1 Materials ........................................................................................................... 29
5.6
Condensation Curing RTV-2 Systems .......................................................................................... 31
5.7
Mould Making Condensation Curing RTV-2 Materials ............................................................... 31 5.7.1 Speciality Mould Making RTV-2 Materials ..................................................................... 32
5.8
Condensation Curing RTV-2 Compounds for Encapsulation ...................................................... 32
5.9
Adhesives and Sealants Based on Condensation Curing RTV-2 Compounds ............................. 33
5.10 Addition Curing RTV-2 Systems .................................................................................................. 33
1
Silicone Elastomers
5.11 Silicone Gels ................................................................................................................................. 34 5.12 Addition Curing Systems for Mould Making ............................................................................... 35 5.13 Addition Cured RTV-2 Systems for Encapsulation ...................................................................... 35 5.14 Addition Cured RTV-2 Adhesives and Sealants ........................................................................... 36 5.15 Addition Cured RTV-2 Foam for Compressible Gaskets ............................................................. 36 6.
7.
2
Liquid Silicone Rubber ......................................................................................................................... 37 6.1
General .......................................................................................................................................... 37
6.2
Curing Mechanism of Liquid Silicone Rubbers ........................................................................... 37
6.3
Standard Liquid Silicone Rubbers ................................................................................................ 38
6.4
Speciality LRs ............................................................................................................................... 39 6.4.1 High Tear LR .................................................................................................................... 39 6.4.2 No Post Cure LR .............................................................................................................. 39 6.4.3 Heat Stabilised LR ............................................................................................................ 40 6.4.4 Coolant Resistant LR (NPC) ............................................................................................ 41 6.4.5 Self Lubricating LR (NPC) .............................................................................................. 41 6.4.6 Oil Resistant LR (NPC) .................................................................................................... 42 6.4.7 Self Adhesive LR .............................................................................................................. 42 6.4.8 Electrically Conductive (Antistatic Silicone!) LR ........................................................... 46 6.4.9 Flame Retardant LR ......................................................................................................... 46 6.4.10 Extra Liquid Rubber (XLR®) ........................................................................................... 47 6.4.11 Other Types of LR ............................................................................................................ 47
6.5
Pigment Pastes .............................................................................................................................. 47
Solid Silicone Rubber ............................................................................................................................ 47 7.1
General .......................................................................................................................................... 47
7.2
Curing Mechanisms of Solid Silicone Rubbers............................................................................ 48 7.2.1 Addition Cure ................................................................................................................... 48 7.2.2 Peroxide Cure ................................................................................................................... 49
7.3
Standard Solid Silicone Rubbers .................................................................................................. 49
7.4
Speciality HTV (all peroxide) ...................................................................................................... 50 7.4.1 High Tear HTV ................................................................................................................. 50 7.4.2 Economy High Tear HTV ................................................................................................ 50 7.4.3 Extrusion HTV ................................................................................................................. 50 7.4.4 Cable HTV ........................................................................................................................ 50 7.4.5 Oil Resistant HTV (NPC) ................................................................................................. 50 7.4.6 Electrically Conductive HTV ........................................................................................... 51 7.4.7 Super Heat Stable HTV .................................................................................................... 51 7.4.8 High Green Strength/Coolant Resistant HTV .................................................................. 52 7.4.9 Steam Resistant HTV ....................................................................................................... 52 7.4.10 Heat Conductive HTV ...................................................................................................... 52 7.4.11 HTV for Transmission and Distribution (T&D) Applications ......................................... 53
7.5
Addition Cured HTV .................................................................................................................... 53 7.5.1 Introduction ...................................................................................................................... 53 7.5.2 Addition Curing ................................................................................................................ 53
Silicone Elastomers
7.5.3 7.5.4 7.5.5 7.5.6 7.5.7 8.
9.
Moulding: 1K Addition Cured HTV ................................................................................ 54 Moulding: 1K Self Adhesive Addition Cured HTV ......................................................... 55 Moulding: 2K Addition Cured HTV ................................................................................ 55 Extrusion HTV ................................................................................................................. 56 Post Curing of Addition Cured HTV ............................................................................... 56
Processing Silicone Elastomers ............................................................................................................ 56 8.1
RTV-1 Systems ............................................................................................................................. 56
8.2
RTV-2 Systems ............................................................................................................................. 56 8.2.1 Mould Making: Flexible Moulds ..................................................................................... 57 8.2.2 Mould Making: Block Moulds ......................................................................................... 58 8.2.3 Mould Making: Skin Moulds ........................................................................................... 58
8.3
LR and HTV ................................................................................................................................. 58 8.3.1 Press Curing HTV ............................................................................................................ 58 8.3.2 Transfer Moulding HTV ................................................................................................... 58 8.3.3 Injection Moulding LR and HTV ..................................................................................... 59 8.3.4 Extrusion of HTV ............................................................................................................. 62 8.3.5 Moulding HTV (General) ................................................................................................. 62 8.3.6 Calendering HTV ............................................................................................................. 63 8.3.7 Rollers ............................................................................................................................... 64 8.3.8 Bonding ............................................................................................................................ 64
Summary ................................................................................................................................................ 64
Additional References ................................................................................................................................... 65 Abbreviations and Acronyms ....................................................................................................................... 65 References from the Rapra Abstracts Database .............................................................................................. 67 Subject Index ....................................................................................................................................................... 153
The views and opinions expressed by authors in Rapra Review Reports do not necessarily reflect those of Rapra Technology Limited or the editor. The series is published on the basis that no responsibility or liability of any nature shall attach to Rapra Technology Limited arising out of or in connection with any utilisation in any form of any material contained therein.
3
Silicone Elastomers
4
Silicone Elastomers
1 Introduction
1.1 Nomenclature
Silicone elastomers are elastic substances which contain linear silicone polymers crosslinked in a 3dimensional network.
The nomenclature classifies silicone elastomers by their curing mechanism and curing conditions. Silicone rubbers are essentially divided into two groups of materials, i.e., room temperature vulcanising (RTV) and high temperature vulcanising (HTV). RTV systems are able to cure at room temperature and HTV systems at temperatures well above 100 °C. A number in the name indicates the number of components that upon mixing will form a curable composition, e.g., RTV-2.
In most cases this network also contains a filler which acts as a reinforcing agent or as an additive for certain mechanical, chemical or physical properties. In general all silicones (usually we refer to silicones as polydimethyl siloxanes) are noted for their high thermal stability, biocompatibility, hydrophobic nature, electrical and release properties. When silicones are crosslinked to form a silicone rubber their characteristic properties are still prevalent. Hence silicone elastomers can be widely used in a great variety of applications. Some examples are shown in Table 1. These will be described in more detail when concentrating on specific groups of materials and applications. We will not refer too much to silicone adhesives in this article, in spite of the fact that they form silicone elastomers when being cured. These materials have been referred to extensively in the literature (a.1, a.2).
HTV rubbers are mainly so-called solid silicone rubbers. They have a very high viscosity in the uncured state and appear as solids. This behaviour has also led to the creation of the term ‘High Consistency Rubber’ (HCR). Approximately 25 years ago a new group of materials appeared that was intended for processing in injection moulding machines. Because of their low viscosity and paste-like behaviour they were named liquid silicone rubbers (LSR) or simply liquid rubbers (LR). It is common to use LSR or LR as an abbreviation instead of HTV, even though they vulcanise at high temperatures as in the case of solid silicone rubbers.
Table 1 Brief overview of applications for silicone elastomers Application area
Applications
Automotive
Exhaust pipe hangers Crank shaft seals Radiator seals Ignition cables Connector seals Spark plug boots
Medical
Catheters Respiration masks Various valves (e.g., dialysis apparatus) Anaesthetic tubing (composite) Body contact electrodes X-ray opaque shunts Various pads
Wire and cable
Wear resistant cables Instrument cables Safety signal cables Safety power cables Battery cables Economy grade cables Heat resistant cables Cable sleeving, wear resistant Cables from silicone rubber pellets
continued…
5
Silicone Elastomers
Table 1 Brief overview of applications for silicone elastomers continued Application area
Applications
Sanitary and household
Gaskets in tap water equipment Gaskets for toilets O-rings (composite) Various valves
Transmission and distribution (T & D) Electronics
Medium and high voltage insulators Medium and high voltage cable accessories Anode caps and cables Key pads (composite) Various gaskets Encapsulation Coatings Adhesives Pottings
Food appliances
Food dispensing valves Various gaskets Baby care articles
Mould making
Prototyping Models for design and/or display Functional models Pre-series models Working moulds for gypsum Plaster moulding Ornaments and window frames Moulded furniture parts Imitation leather moulds Moulds for shaped foodstuffs (e.g., chocolate) Do-it-yourself (DIY) applications Archaeological applications Restoration
For the most part all LR materials are 2 component systems which cure after mixing and at elevated temperatures.
In this article I will concentrate on applications, requirements and materials and why to choose silicone elastomers in the cases discussed.
In summary the silicone industry uses the terms RTV1, RTV-2, LR or LSR, HTV or HCR. These refer to the material categories as follows:
The second half of this review will concentrate on the various types of silicone elastomers, their chemistry and processing.
RTV-1
Room temperature vulcanising, one component
RTV-2
Room temperature vulcanising, two component
2 Silicone Elastomers Market
HTV
LR
6
High temperature vulcanising, solid silicone rubber, high consistency rubber Liquid rubber, liquid silicone rubber (which is also cured at high temperatures).
In 1999 the global market consumed approximately 170,000 tons of silicone elastomers. Figure 1 shows the market shares between the material categories. Among all silicone elastomers LR exhibits the highest growth rate and HTV has the highest portion of the market.
Silicone Elastomers
The specific requirements of car builders and their system suppliers have made silicone elastomers an indispensable raw material for automotive components. One should also mention that silicone fluids, fumed silica, tyre release agents, paint additives, silicone polish and resins are as indispensable for car components as silicone elastomers. The key reasons for the consumption of silicones in automotive applications are numerous. Heat resistance, cold flexibility, oil and chemical resistance mainly account for the use of silicones in the engine and areas close to the engine.
Figure 1 Silicone elastomers world market by material categories
3 Applications for Silicone Elastomers 3.1 Automotive Table 2 provides a rough overview of the most common automotive applications for silicone elastomers and indicates suitable silicone elastomers.
Long-term properties such as ‘infinite’ flexibility and low compression set make silicones the perfect choice for airbag coatings, gaskets, bellows, profiles, etc. Very high dielectric strength and surface resistance, and hydrophobic behaviour are required in electric installations for cars. This, however, holds for most wire and cable applications. Apart from being ‘perfect’ electrical insulators, silicone elastomers can be modified to become electrically conductive parts which are then
Table 2 Important automotive applications for silicone elastomers Applications
Type of silicone elastomer RTV-1
RTV-2
LR
HTV
Exhaust pipe hangers
X
Crank shaft seals
X
Radiator gaskets
X
X
Ignition cables
X
Battery cables
X X
X
X
X
X
Single wire seals
X
X
Switch covers
X
X
Connector seals Spark plug boots Rapid prototyping
X
Brake anti-blocking system (ABS) control sealing
X
X
Airbag coating
X
X
X
X
X
X
X
X
X
Airbag trigger and electronics Bellows
continued…
7
Silicone Elastomers
Table 2 Important automotive applications for silicone elastomers continued Type of silicone elastomer
Applications
RTV-1
RTV-2
LR
HTV
Electric and electronic components
X
X
X
X
Cured-In-Place-Gasket (CIPG)
X
X X
X
Vibration dampers
X
Vent flap gaskets
X
Radiator hoses
X
Air conditioning gaskets and electronic components
X
Oil filter valves Air filter gasket
X
X
X
X
X
X
X
Air flow mass sensor
X
Oil pan gaskets
X
X
O-rings Profiles
X
Lighting gaskets
X
X
Silicone sponge
X
X
X
X
Sun roof gaskets
X
Turbo charger hoses
X
Membranes
X
X
X
X
Wiper blades
X
X
Power lock system/gaskets
X
X
X
X
X
Ignition coil protection
Cylinder head gaskets
X
Gear box gaskets
Table 3 Key requirements in automotive applications for elastomers Applications
Property requirements
Engine
Heat resistance
Cold flexibility
Oil and chemical resistance
Easy processing
Transmission/moving parts
Heat resistance
Cold flexibility
Oil and chemical resistance
Easy processing
Airbag
Heat resistance
Cold flexibility
Low compression set
Long-term integrity
Electronics
Electric insulation
Heat/cold resistant
Long-term integrity
Hydrophobic nature
Electrical installations
Electric insulation
Heat/cold resistant
High dielectric strength
Hydrophobic nature
Low compression set
Easy to process
UV stable
Heat/cold resistant
Car body and lighting
8
Silicone Elastomers
used, for example, in parts for the ignition system (such as the ignition cable inner lead and spark plugs). The dielectric and other properties make them suitable for spark plug boots and encapsulation of electronic components (even safety components such as airbag and ABS controls). Any application related to the car body is subjected to most of the property requirements already mentioned. UV stability is another predominant requirement for parts used in such applications. The term ‘stability’ means that a material will not immediately or slowly change its properties over time on exposure to a certain condition. In other words, a given mechanical and/or chemical parameter should change as little as possible. In most cases specifications include relative changes over time (changes in percentage of a property value compared to the initial values). Property requirements for automotive applications are shown in Table 3.
3.2 Healthcare and Medical Table 4 provides a rough overview of the most common applications and suitable silicone elastomers in medical devices, healthcare applications and related areas. The field of applications for silicone elastomers is as wide in medical applications as in the automotive sector. Furthermore this is a growing sector, because of the substitution of other organic elastomers, such as latex, and thermoplastics, such as PVC. Reportedly silicone elastomers have often been discussed as the ideal material for medical devices and applications. This also includes the genetics, biotechnology and pharmaceutical industries. The main reason for this great interest in silicone rubber is due to its biocompatibility. For example, silicone rubbers show: NO pyrogenicity (NO body temperature reaction), NO haemolysis (NO red blood cell destruction) and NO cytotoxicity (do not affect live cells).
Table 4 Healthcare applications for silicone elastomers Type of silicone elastomer Applications
RTV-1 adhesive
RTV-2
LR
HTV
Catheters
X
X
X
Respiration masks
X
X
X
X
X
Respiration bellows Anaesthetic tubing
X
Tubing connectors
X
X
Body electrodes
X
X
X-ray opaque shunts
X
X
X-ray opaque drains
X
X
X-ray opaque catheter tips
X
X
X-ray opaque tubing markers (coextruded)
X
X
Operating room pads
X
X
Pads for incubators
X
X
Catheter balloons
X
Catheter funnels Electric and electronic components Valves
X
X
X
X
X
X
X continued…
9
Silicone Elastomers
Table 4 Healthcare applications for silicone elastomers continued Type of silicone elastomer Applications
RTV-1 adhesive
RTV-2
LR
HTV
Stoppers
X
X
Gaskets
X
X
O-Rings
X
Gaskets for dialysis equipment
X
X
Pads for operation instruments
X
X
X
X
Syringe pistons
X
X
Medication dispensing valves
X
X
Inhalation aids
X
X
Body electrodes
Orthopaedic devices
X
X
X
Bouncing putty (for physiotherapy) Membranes
X
Short-term implants
X
Prosthetic devices (external)
X
X
Printing ink
X
X
Dental masses
X
Rapid prototyping
X
Silicone gel pads
X
Sensoric equipment
X
Thus correctly produced and treated silicone parts made out of selected materials suitable for medical devices will pass tests according to ISO10993 and US Pharmacopoeia Class VI, European Pharmacopoeia and other protocols. Figure 2 shows certificates from test laboratories as obtained on the biocompatibility of ELASTOSIL® R4110/60 and 4305/40, silicone elastomers produced by Wacker. The key reasons for the consumption of silicones in medical/pharmaceutical devices and equipment are: biocompatibility, gamma ray resistance, chemical resistance, sterilisability (gamma ray, ethylene oxide (EtO), steam), pigmentability, transparency, durability, and the fact that they are non allergenic. In addition, all the properties mentioned under the automotive section (3.1) also complement their
10
X X
X
X
X
competitive advantages compared to other organic elastomers. As many medical devices must be manufactured under special hygienic conditions, in compliance with Good Manufacturing Practice (GMP), in cleanrooms, silicones seem to be a good choice of materials as well. In many cases they can be processed almost without forming any reaction products, which might impair purity, smell or sterility of the manufactured goods. Silicones are not only bioinert, their excellent electrical insulating properties make them a useful component of any medical equipment, be it sensoric, or for resuscitation, etc. This is also supported by their hydrophobic behaviour, which prevents them from accumulating moisture from the surrounding environment.
Silicone Elastomers
Figure 2 Certificates on the biocompatibility of ELASTOSIL® R4110/60 and 4305/40
Table 5 summarises most of the mentioned properties as they relate to areas where medical devices are most commonly used. Summing up we can draw the conclusion that silicones have a great future in medical device technology. However, their reputation as long-term implants has been sullied after the bad press and the vast number of lawsuits with respect to silicone breast implants. In order to support the duty of care of suppliers to the medical device industry, in most cases silicone manufacturers have set internal healthcare guidelines. Basically these list allowed applications for each
material and those that are not supported by the silicone manufacturer. As a general rule, many silicone manufacturers restrict their supply to this industry to short-term implants. In other words, the providers of silicone elastomers will not usually support implants or devices involving permanent body contact (longer than 29 days).
3.3 Wire and Cable Silicone rubbers are used for applying an electrically insulating layer onto the conductive thread of a cable. Many of these insulations are made of HTV silicone rubber.
Table 5 Properties of silicone elastomers relevant for medical devices Applications
Property requirements
Steam sterilisers
Heat resistance
Steam resistance
Chemical resistance
Hydrophobic nature
Human body
Biocompatible
Chemical resistance
Resterilisable, non allergenic
X-ray opaque silicones useful
Respirators
Biocompatible, skin friendly
Resterilisable, non allergenic
Long-term integrity
Anaesthesia
Resterilisable, non allergenic
Long-term integrity
Transparent
Electric equipment
Electric insulation
Heat resistant
High dielectric strength
Hydrophobic nature
11
Silicone Elastomers
Table 6 Wire and cable applications using silicone elastomers Applications
Type of silicone elastomer RTV-2
LR
HTV
Pelletised HTV
X
X
X
X
Instrument cables
X
X
Battery cables
X
X
Safety signal cables
X
X
Safety power cables
X
X
Economy grade cables
X
X
Heat resistant cables
X
X
Wear resistant cables
Composite cables
X
X
X
Cable sleeving
X
X
X
X
X
Ignition cables Cables from silicone rubber pellets High and medium voltage cables
Increasingly, the latest development, i.e., pelletised silicone rubber is being used in such applications. Existing and innovative applications are shown in Table 6. The specific requirements for silicone elastomers that are used in cables develop from the requirements of cable manufacturers and their end users. As to manufacturers in particular, the silicone rubber must be easily extrudable in order to allow outputs of up to 400 m/min of ready made cable. Typically cable insulations made of HTV will exhibit a dielectric strength of 18-20 kV/mm and a volume resistivity of 1015 Ωcm. End users often specify their cables to comply with international and national standards, such as the VDE standards. The most important requirement for the silicone in this application is the heat resistance. The VDE standard, VDE 0303, specifies an elongation at break of >200% after heat ageing for 10 days at 200 °C. The use of silicone rather than PVC or other thermoplastic and elastomer materials, has been boosted by safety discussions after recent fire accidents in which most of the damage was unfavourably attributed to the contribution of the PVC sleevings to smoke toxicity and density and cable function. Silicone
12
X X
X
cables burn at a much slower speed and their combustion products have low toxicity. During combustion silicone degrades to silica. Hence, most of the silicone forms an electrically insulating ash. This prevents short circuits and their consequences. The accidents referred to above gave rise to the rapid development of so-called safety cables. Such cables will maintain the integrity of the electric circuit over a certain period of time in the case of a fire. Using special silicone grades, such as ELASTOSIL® R 502/ 75 from Wacker Chemie GmbH, enables cable manufacturers to produce a safety cable which will maintain circuit integrity over 90 minutes at temperatures higher than 1,000 °C even if they are quenched with water. This technology is based on the fact that ceramics are electrical insulators. ELASTOSIL® R 502/75 turns into a ceramic when it is being burned. It goes without saying that the safety of such cables is also a question of design. Very recent developments have led to addition cured safety cable compounds and compounds which form an even harder ceramic. These are summarised in Table 7 (a.3). A further competitive advantage of these safety cable materials is the fact that they can be extruded at very high speeds (of up to 400 m/min) whereas more
Silicone Elastomers
Table 7 Newly developed safety cable grades Material type
Description
Remarks
ELASTOSIL® R 502/75
Peroxide cure, ceramising on combustion Cables pass UL2196 test
Available in pellets, pigmentable, pass VDE requirements on heat resistance
ELASTOSIL® R 503/75
Peroxide cure, ceramising on combustion Forms much harder ceramic
Available in pellets, pigmentable, pass VDE requirements on heat resistance
ELASTOSIL® R 543/70
Addition cure, ceramising on combustion
Available in pellets, pigmentable, pass VDE requirements on heat resistance
Table 8 Requirements for insulating materials in wire and cable applications Applications
Property requirements
Safety cable
Extrudability and delamination
Steam resistance
High dielectric strength
Forms hard ceramic on combustion
Wear resistant
Extrudability
Mechanical properties
High dielectric strength
Low wear
Economy grade
Extrudability and delamination
High dielectric strength
No special requirements
Heat resistant grade
Heat stability, 20,000 h at 200 °C
Extrudability and delamination
High dielectric strength
Flame retardant
High limiting oxygen index (LOI)
Extrudability and delamination
High dielectric strength
Wear resistance
Pigmentability
Cable sleeving primer Good adhesion
traditional safety cable technology allows only a few metres per minute. For example, mica tape safety cables have a production rate of 12 m/minute. Table 8 summarises most of the properties of silicones relevant to wire and cable applications.
Recently developed new technologies such as silicone rubber pellets, safety cable grades and wear resistant cables have also led to new application areas for silicone rubbers/elastomers used as cable insulation material.
3.4 Sanitary, Household and Leisure Over the past years the cable markets have degenerated into a commodity business. In most cases the cost pressure on industries related to consumer electronics, household appliances and car manufacturers was too high to maintain this as a speciality area. Some cable markets were dominated by silicone rubbers that were heavily filled with quartz in order to bring the cost down (silicone suppliers call this ‘elastic stone’). Today, cable manufacturers are in a renaissance as the requirements have changed. The safety and high quality aspect seems to have gained priority over plain cost calculations.
Apart from wires and cables described under the previous chapter, sanitary and household appliances utilise silicones in tap water equipment and domestic appliances. Table 9 provides a rough overview of common applications and suitable silicone elastomers. The consumption of silicones and, in particular, silicone elastomers in household appliances and related areas such as sanitary, gardening, agricultural and leisure equipment is enormous. The growth of such applications is often due to the substitution of other organic elastomers, such as EPDM and thermoplastic elastomers, etc.
13
Silicone Elastomers
Table 9 Common household and leisure applications for silicone elastomers Type of silicone elastomer Applications
RTV-1 adhesive
RTV-2
LR
HTV
X
X
X
X
Rice cooker gaskets
X
X
Tap water gasket for mixing unit
X
X
Electrical iron gaskets
Tap water gasket for fittings
X
Boiler gaskets
X
X
Gasket for washing machine doors
X
X
Vibration dampers in washing machines
X
X
Gaskets for dishwashers
X
X
O-rings
X
X
Tubing for vending machines
X
Valves for coffee and tea machines
X
X
Pressure cooker gaskets
X
X
X
X
Microwave gaskets/components
X
Oven door seals (profiles)
X
Spark plug boots (lawnmower, etc.) Safety applications
X
Valves Silicone sponge
X
X
X
X
X
X
X
X
Gaskets
X
X
Shower head nozzles (composite with TP)
X
X
Nose pads (glasses)
X
X
Swimming caps
X
X
Membranes for irrigation systems
X
X
Membranes
X
X
Diving mask
X
X
Diving equipment
X
X
In most cases the properties of silicone elastomers are more favourable than those of organic rubbers. Silicone elastomers allow a high degree of automation in processing. However, material costs are relatively high and cost is an important factor in this application area. As in most applications in this field mass production is prevalent, annual production is usually 100,000 or more pieces, hence the processing advantages of silicone rubber can drastically improve the cost structure.
14
In other words, when processing an elastomer the cost of the ready made piece often depends on the processing cost per piece rather than the cost of the material consumed per piece. Any difference in material cost between silicone elastomers and other rubbers/elastomers is deceptive therefore, because it does not indicate the differences in the specific complexity and duration of processing.
Silicone Elastomers
In many cases silicone elastomers are processed without any major secondary operations. It is also possible to eliminate any manual steps in production. The consequence is a much higher accuracy and consistency of the production process and substantial cost savings. Silicone rubbers, when processed and post cured correctly do not usually affect the taste of the surrounding media. Other properties such as lack of cytotoxicity have been discussed in Section 3.2; thus silicone rubber is useful for tap water equipment. In comparison to organic rubbers, silicone elastomers do not contain any harmful substances such as nitrosamines. The nitrosamine level in silicones is below detection level or below the common limit of 10 ppb after correct processing. The levels of nitrosamines are higher in some organic rubbers. Their origin is thought to be in the curing system which contains amines. As a consequence, apart from the effect on smell and taste, nitrosamines remain in the rubber (a significant proportion are non volatile, and thus would not evaporate over time). In drinking water applications a number of international and national regulations apply, administered by: The
National Sanitation Foundation (NSF) in the US, Water Regulations Advisory Scheme (WRAS) in the UK, and the KTW guidelines in Germany, etc. Silicones are suitable for most of these standards. Producers of raw materials usually have a number of suitable materials with a KTW or WRAS certificate. These certificates also include colours, as shown in Figure 3. Even though many materials are contained in such certificates, the end seller will have to produce a separate approval certificate for his own system. In this area of applications design aspects are of importance, such as pigmentability and transparency. Further, compared to other plastics or rubbers, standard silicones will produce no toxic gases and low smoke density should they burn. Additionally, standard silicones will have lower inflammability than organic rubbers. Thus, all silicone rubbers would pass a UL94 HB flame test (a.4). Special additives can be used to increase this further, resulting even in UL94 V0 ratings. Table 10 summarises most of the properties of silicone elastomers related to household and similar areas.
Figure 3 WRAS and KTW certificates (reproduced with permission)
15
Silicone Elastomers
Table 10 Property requirements in household applications Applications
Property requirements
Electrical domestic appliances
Heat and steam resistance
Low compression set
Chemical resistance
Hydrophobic nature
Tap water equipment
Approval from WRAS, KTW
Low compression set
Tasteless
No sticking of CaCO3 deposits
Sporting goods
Biocompatible
High tear strength
Transparent and pigmentable
UV stable
Skin friendly
Long-term integrity
Pigmentable
High tear strength
Gas permeable
Agriculture (e.g., irrigation)
Low compression set
Chemical resistant
Long-term integrity
Good processability
3.5 Transmission and Distribution These applications cover the transmission and distribution of electric power. Special silicones are the best choice for medium and high voltage cable accessories and insulators as described below. Historically, the transmission and distribution applications for silicones developed from normal porcelain insulators which were covered with silicone grease in order to achieve hydrophobicity. Later, silicone rubber dispersions were used to cover porcelain with a rubbery and hydrophobic layer. Today, after 30 years of development, insulators tend to consist entirely of special silicone rubbers. Most of them contain special fillers allowing for more enhanced electrical properties. The technology of silicone rubber pellets is also available for these special grades resulting in processing advantages.
For performance reasons silicones are increasingly used in these areas as ceramics and organic rubbers do not show the same degree of performance, particularly in medium and high voltage applications. Table 11 gives a list of key applications and the silicone elastomer type used. Even though the number of applications listed in the above table is seemingly quite small the requirements are various and the scope of these applications is enormous. The most important properties are based on the electrical parameters of silicone rubbers, such as dielectric strength (around 18-20 kV/mm), volume resistivity (10 15 Ωcm) and surface resistance (1013 Ω). As yet mentioned under earlier chapters these properties are the reason for the suitability of silicone rubbers for electrical applications.
Table 11 Transmission and distribution applications utilising silicone elastomers Applications
Type of silicone elastomer LR
HTV
Pelletised HTV
Long rod insulators
X
X
X
Stress cones
X
X
X
X
Cold shrink connectors
X
X
Medium and high voltage connectors
X
X
Cable accessories
Medium and high voltage insulators
RTV-2
X
X
Conductive silicone rubbers Conductive primers
16
X X
X
X
X
Silicone Elastomers
A further asset of silicones is their hydrophobic behaviour which is of importance in many outdoor transmission and distribution applications. As a result of their hydrophobic nature, silicone insulators show much smaller leakage currents than porcelain or EPDM offsets. Even in cases of high contamination (even if conductive!) silicone insulators will remain hydrophobic along their surface. Silicone elastomers are capable of turning deposits from their environment (such as dust, sea salt, etc.) hydrophobic. This is due to the small amount of siloxanes bleeding out of the elastomer surface, covering the deposit and rendering it hydrophobic. Even after cleaning the insulators with detergents the hydrophobic behaviour will remain or return in due course. This is called hydrophobic transfer and regeneration. Insulators in outdoor applications often are in contact with moisture. This is why tracking resistance is of utmost importance, silicone rubbers for these situations have tracking resistance >2.5kV. (Special silicone grades provide a tracking resistance of ≥4kV.)
Long life, resistance to severe conditions and other properties make silicone elastomers suitable material for electric insulators in transmission and distribution applications. This is particularly of importance where electric energy must be distributed in desert or coastal areas, where the most severe conditions occur.
3.6 Electronics Silicone elastomers are highly rated materials for electronic components. Their main use is encapsulation and in composites, as summarised in Table 13. Many applications in this sector can also be referred to as household, automotive, consumer, etc., applications. However, they are dealt with in this section as their main purpose is to protect and/or allow the performance of electronic components. HTV, LR or RTV-1 silicones are only used in a few cases. This has to do with the fact that electronic components are too sensitive chemically for RTV-1 and mechanically for LR or HTV to allow for their use (Table 13).
UV and ozone resistance complement the spectrum of properties.
For encapsulation of electronic components, potable RTV-2 systems provide the best solution. Typically, they are transparent or opaque and exhibit low viscosities or thixotropic behaviour. Their pot life is long and their curing time is very short, in particular after slight heating of the mix. In order to provide maximum performance with respect to electrical properties and corrosive behaviour their ion content is very low. Special systems will perform well down to –100 °C. As to vibrations, shocks, etc., they provide maximum mechanical protection of the encapsulated electronic system due to their mechanical damping properties.
Table 12 summarises the properties required for different application areas, where specialty silicone rubbers are used in the transmission and distribution industries.
One of the most popular electronic applications in the automotive sector are so-called weather packs. These are described in Section 6.4.5 of this review. In most cases one would use oil exuding LR.
Should flashovers take place special silicone elastomers also exhibit excellent resistance to electric arcs. Needless to say, as silicone elastomers have relatively low changes of properties over time and temperature they are very suitable for long-term applications and for varying conditions. Silicone elastomer insulators can resist temperatures down to –45 °C, remaining flexible.
Table 12 Property requirements for raw materials used in transmission and distribution applications Applications
Properties
Insulators
Arc resistance
Tracking resistance
High dielectric strength
Hydrophobic nature
Cable accessories
High dielectric strength
Tracking resistance
Arc resistance
Long-term integrity
Outdoor use
Hydrophobic nature
Tracking resistance
Arc resistance
High dielectric strength
17
Silicone Elastomers
Table 13 Electronic applications of silicone elastomers Type of silicone elastomer Applications
RTV-1 adhesive
RTV-2
ABS controls (electronic control unit (ECU))
X
X
Ignition controls
X
X
Airbag controls
X
X
Theft protection Sensors
LR
HTV
X X
X
Air flow meters
X
X
Monitors
X
X
X
Anode caps
X
X
Keypads
X
X
X
X
X
X
Cellular phones
X
X
X
Power modules
X
Optocouplers
X
Surface wave filters
X
Diodes, transistors
X
X
Electromagnetic shielding
X
X
High performance adhesives
X
X
Control devices
X
X
X
X
Instrumentation
X
X
X
Encapsulation of electronic components
X
Adhesives for electronic components
X
X
Maximum reliability is crucial in safety applications such as ABS and airbag control or medical electronic equipment, for instance.
Needless to say, easy processing is a must. This allows for high output rates in processing and a good degree of flexibility.
This requires optimum adhesion to circuit boards and housing, low modulus (thus high flexibility) and the absence of solvents, the latter is also required for environmental compatibility.
A good example of a consumer electronic application are anode caps for TV sets. Typically, they would also be part of electroencephalogram (EEG), electrocardiogram (ECG) and related equipment, and all applications requiring high voltage such as in the case of anodes of tubes for TV screens. The requirements are very high dielectric strength, flame and heat resistance. As anode caps, safety switches, etc., originate from moulding processes, it is also required that the curing times be very short.
Some applications require very high thermal conductivity (to allow for the transfer of heat), materials up to 2.0 W/mK are used for such applications. For example, thermal conductivity is a must for sensoric equipment, e.g., for temperature measurement. As mentioned earlier silicones are excellent electrical insulators. This, their mechanical properties and their hydrophobic character make them suitable for electronics.
18
Table 14 shows inflammability ratings and limiting oxygen indices of various liquid silicone rubbers and HTVs including the Underwriters’ Laboratory (UL) classifications (a.4).
Silicone Elastomers
Table 14 Flame retardant and electrical properties of some silicone elastomers Material name (ELASTOSIL® Grade)
Material type
LOI (%)
Achievable UL 94 rating
Dielectric strength (kV/mm)
LR 3003/50
LR, key pad
26
HB
23
LR 3001/55
LR, anode cap
35
V0
27
R 401/70
HT V
23
HB
20
Materials for electronic key pads require utmost durability (number of cycles of pressed keys), very high resistivity and pigmentability. Most key pads are also painted and/or printed with special inks. Good adhesion of such inks complements the requirements. Special ink formulations provide excellent adhesion and wear resistance. They are, of course, silicone based.
Apart from the minor part of applications in electronics that are produced by injection moulding such as anode caps (with the exception of weather packs), most of the products are produced by using potting technology.
Cellular phones, radios and electronic controls often work with electromagnetic signals. In order to shield their electronic interior one has to use special housings. These housings are sealed with gaskets which act as an electromagnetic shield. As with all gaskets they have to be elastic over a wide range of conditions. Thus, silicone is the best choice. Special silicones are equipped with highly conductive additives that allow for sufficient shielding. Rapid curing and adhesive properties are further complementing properties. The silicone elastomers are applied by robots onto plastic frames and/or housing.
Potting is a technology that is used in order to protect electronic devices. Fully automatic processing involves single or multicomponent mixing and metering equipment. This apparatus is usually part of a mass production process. Silicone elastomers in use here are designed for simple mixing ratios and the individual components in most cases have viscosities of the same order of magnitude. Fully automatic and highly accurate application techniques have evolved.
Special silicone elastomers are also applied in the manufacture of electronic chips and for solar cells in aerospace applications. This implies UV stability, resistance against irradiation, low volatiles and optimum adhesion.
RTV-1 and RTV-2 UV curing systems are known as well as HTV, 1- and 2-component materials.
Such properties allow their use in power modules such as components of rectifiers, welding equipment, elevators, etc. Optocouplers often contain RTV-2 silicone gels because of their high transparency. Such gels can be made thixotropic by certain additives which allows partial coverage. Good electrical properties and insensitivity to thermomechanical stress and temperature changes complement the advantages of the use of silicone gels. One of the most important properties of silicone elastomers in electronics is long-term integrity. This allows for their use in long lasting sensors and encapsulated circuit boards.
As this technology refers to electronics for the most part it will be described briefly.
Potting is used in covering chips, hybrid circuits, power modules and other devices.
Potting compounds can be very soft and flexible, but also rigid or highly elastic. Soft gels are recommended for covering highly sensitive components. Potting systems can be: •
low viscosity or thixotropic
•
highly transparent
•
flame retardant
•
thermally conductive
•
fuel resistant
•
cold resistant
•
resistant against thermal shock
•
low shrinkage
•
adhesive to plastics
•
low volatile (low outgassing)
•
good damping properties.
19
Silicone Elastomers
Table 15 Properties required for electronics applications Applications
Property requirements
Automotive electronics
Heat and cold resistance
Vibration damping
Dielectric properties
Low Young's modulus
Power electronics
Heat resistant
Low Young's modulus
Easy processing
Wide range of mechanical properties
Sensors
Transparent
Long-term integrity
UV stable
Wide mechanical spectrum
Low inflammability
Long-term integrity
Good processability
Consumer electronics Electric insulators
Table 15 summarises most of the properties required for applications in electronics.
3.7 Mould Making Whenever I mention mould making in conjunction with RTV materials or in the present chapter, I do not mean the construction of moulds for injection or press moulding, as required for the processing of LR and HTV. Silicone elastomers are used in the production of flexible moulds for pourable, spreadable or pastelike materials which solidify in certain conditions and subsequently lead to variously shaped products. Some of these applications might also be described as household, automotive, consumer, semiconductor, etc. However, they differ from the previous sections because the silicone is used to make parts of a different material which is not necessarily elastomeric. All mould making materials are limited to RTV-2 systems. A distinction is made between condensation and addition curing systems. This is based on the reaction mechanisms of the two systems. Table 16 describes the applications of silicone elastomers in mould making. The main intention of mould making in these applications is quick and simple reproduction of certain shapes. This is the case if one wants to copy a unique original, to duplicate a master copy, or a prototype, or to repair damage. As each mouldable material has its specific characteristics, the range of available mould materials is broad.
20
The biggest requirement for a mould making material is chemical resistance, as the chemical nature of most mouldable materials is at least slightly aggressive under moulding conditions. Chemical resistance is characterised by the change of a certain property over time. If this change is relatively small, the mould making material will allow a very high number of moulding cycles. This number would obviously be lowered drastically as a consequence of, e.g., premature embrittlement, which can be caused by excessive heat. This would be the case if one uses an organic rubber with relatively low heat resistance compared to silicone. Flexibility is possibly the second most important property of silicone elastomers in mould making. The mould should be capable of accurately reproducing the surface details of the original design. However, at the same time it must allow for optimum release properties. Silicone elastomers have a unique chemical structure, which is responsible for such release properties (as a result of the highly hydrophobic nature). Block moulds are produced by pouring or impression techniques. This is mainly done if one has to copy only one side of the original, and it will allow only for ‘shallow’ undercuts. Small models with simple undercuts are made from block moulds of two or more parts by pouring or impression. Copying deeper undercuts requires skin moulds as obtained by spreading, dipping or pouring. Such moulds need a rigid mechanical support, such as plaster or laminate. If undercuts become more complicated one will use a skin mould of two or more parts (using a spreading technique for bigger upright objects).
Silicone Elastomers
Table 16 Silicone elastomers for mould making Type of silicone elastomer Applications
RTV-2 Addition cure
Industrial moulds
X
Prototypes
X
Models for design and/or display
X
Functional models
X
Pre-series models
X
Wax models
X
Small series (alternative to injection moulding)
X
X
Gypsum or plaster moulds
X
X
Porcelain moulds
X
Sanitary ceramics
X X
Leather imitation
X X
Glass reinforced plastic (GRP) laminates
X X
Electroforming moulds
X
Car interior
X
DIY applications
X
X
Applications in arts
X
X
Archaeological replicas
X
Restoration stucco, ornaments
X
Reproduction materials suitable for use in silicone moulds are:
indeed, true. The reasons are in the compatibility of silicones with their environment, chemical resistance, physical and mechanical properties.
Plaster, cement, concrete, synthetic stone or ceramics
•
Waxes
•
Casting resins such as polyesters, polyurethane resins and foams, epoxy resins and, within limits, acrylic resins
•
X
Ornamental shapes
Moulded foodstuffs
•
RTV-2 Condensation cure
Low-melting metal alloys (melting points below 350 °C).
3.8 Food Sector The reader may have guessed from the use of silicone elastomers in medical device technology that they are also suitable for use in contact with food. This is,
Table 17 provides an overview over food and related applications. Silicone elastomers are used in many different areas ranging from packaging aids or elements to tubings for the food industry. This section is somewhat related to Section 3.4, on the use of silicone in contact with drinking water. However, here we concentrate on applications where silicone rubbers are directly in contact with foodstuffs. Important baby care applications are included in this chapter as baby feeding equipment is one of the larger applications for liquid silicone rubbers. Silicone elastomers in contact with foodstuffs have to comply with relevant legislation and regulations.
21
Silicone Elastomers
Table 17 Food contact applications of silicone elastomers Type of silicone elastomer Applications
RTV-1 adhesive
RTV-2
X
X
LR
HTV
Industrial food dispensing valves
X
X
Baby soothers
X
X
Baby feeding teats
X
X
Nipple shields
X
X
Food dispensing valves in packaging
X
X
Baking tray coatings
Tubing for milking equipment
X
Milk liners
X
O-rings
X
Tubing for foodstuff ingredients
X X
Tubing for fermentation purposes
X
X
Stoppers for wine barrels
X
X
X
X
Baking moulds
X
X
Kitchen spatulas
X
X
Stoppers for wine bottles
X
Perhaps the most famous regulations in that respect are the German BgVV Recommendation XV ‘Silicones’ and the US Food and Drug Administration (FDA) Regulation CFR21 Section 177.2600. These contain positive lists of sanctioned ingredients for rubber parts in contact with food. What is not listed must not be contained in the silicone elastomer formulation. BgVV also regulates the amount of volatile matter in the silicone elastomer. The weight loss of a silicone part must not exceed 0.5% after heat treatment for 4 hours at 200 °C. Further, the two regulations prescribe acceptable levels of extractables, etc.
In the case of baby care applications, which were once dominated by latex, silicone elastomers are becoming more and more prevalent. This has to do with the fact that the curing systems of organic elastomers often include amines and other additives leading to potential toxic contaminants, such as nitrosamines.
Silicone elastomers meet such requirements, if they are processed correctly and have undergone sufficient post cure. Post curing is used in order to finalise vulcanisation and strip off volatiles which are contained in the rubbers as cured. The loss of volatiles from a silicone elastomer during post cure is illustrated in Figure 4, using different thicknesses of samples and different temperatures.
Other favourable properties of silicone elastomers for food contact are sterilisability, steam, heat and chemical resistance which makes them the perfect materials in baking moulds, baking tray coatings and the like. Typically, silicone baking moulds are produced from liquid silicone rubber or addition cured HTV.
Further, post curing also helps to improve physical and chemical properties, such as the compression set. This is shown in Figure 5.
22
On the other hand there are silicone rubbers/elastomers which are amine free and, in most cases, are platinum cured. Such curing systems allow for biocompatibility, as mentioned in the healthcare chapter. Correctly processed parts do not show detectable nitrosamine levels without and after proper post cure.
The silicone rubber has the required heat and chemical resistance. Well established companies specialising in consumer goods and appliances have started to sell these products including life time guarantees and special cooking advice.
Silicone Elastomers
Figure 4 Weight loss of ELASTOSIL® LR 3003/50 as a function of post curing time
3.8 Food Sector
Figure 5 Compression set (DIN 53517) as a function of post curing time and sample thickness for ELASTOSIL® LR 3003/50
The food industry is using silicone elastomers for tubings and fittings. Perhaps one of the most interesting applications in the rubber industry related to food is milking equipment. Predominantly this area has been occupied by nitrile rubbers, which again use potentially unfavourable additives. In the last 5 years silicone elastomers have begun to be substituted in this application. The parts are limited to silicone tubing, milking teats and milk liners. Reportedly, they exhibit a longer life time and are quasi inert with respect to migratable substances in line with the regulations (again proper processing and post curing are a must).
3.9 Other 3.9.1 Safety Applications The most valuable safety property is the fact that silicone elastomers do not burn easily. This means that their limiting oxygen index is always above 20% (a.5, a.6, a.7 and other standards related to flammability), and, burning tests, e.g., UL94 HB, are easily passed. Once a silicone burns the spread of the flame is slow and the combustion products are silica, CO, CO2 and water, products with low toxicity.
23
Silicone Elastomers
Unlike most organic elastomers, silicone will not only form such harmless combustion products, it will also produce very little smoke and, hence, permit a good degree of visibility in the event of a fire. Further, silicones are capable of forming a stable ash, which in extreme cases will turn into very hard ceramic, as discussed under safety cable materials (Section 3.3). The advantage of such an ash forming behaviour during burning is also very useful in the case of door seals, or any kind of gasket that needs to have sealing properties at least against the spread of flames or smoke, as in the case of two sections of a building, for instance. Many of the recent and past accidents in buildings, aeroplanes, ships, etc., could have resulted in a significantly lower number of victims if silicone profiles or cables had been used correctly.
3.9.2 Aerospace Because of their resistance and relatively small variation of properties across a vast temperature range, silicone elastomers have occupied a substantial part of the market for aeronautic applications for rubbery materials. Phenyl methyl silicone elastomers retain low temperature flexibility in extreme conditions even down to –110 °C. The applications of silicone elastomers range from adhesives in satellites and aeroplanes to components of wings, landing flaps, window gaskets, floor components and many more parts. It goes without saying that the other properties of silicone elastomers and rubbers such as heat and UV resistance, and the hydrophobic behaviour, contribute to their wide usage across these industries.
Over the past 5 years the building industry has also put its focus on design aspects. Functional elastomeric profiles are no longer invisible. Moreover, they have become part of the design concept of the buildings. With such design requirements and the conditions that are imposed on large buildings, silicone has become a good option for elastomeric profiles and silicone adhesives are well established. This is mainly due to cold flexibility, almost indefinite UV stability and relatively low compression set. Needless to say, silicone rubber profiles are available in any colour whereas all organic rubbers have certain restrictions.
3.9.4 Pharmaceutical Many pharmaceutical tubings, fittings, gaskets and the like contain silicone rubber, because of its ‘inert’ behaviour towards certain media and its resterilisability.
3.9.5 Spin Casting Silicone elastomers provide an economically ideal solution, for shaping metals with relatively low melting temperatures. These alloys are cast into a rotating silicone disc containing a certain number of cavities. Because of the heat stability of the silicone rubber the number of casting cycles is approximately 100-500 depending on the metal and the size of the parts.
New technologies for modern buildings have evolved over the last 3 decades in the form of structural glazing. This building concept involves covering the fronts of buildings with glass panels.
Silicone rubber has to exhibit an utmost degree of heat and reversion stability. A specially designed solid silicone rubber with a hardness of around 40 Shore A is used as a raw material; it is mixed with ground quartz in order to obtain the required hardness, catalysed with dicumyl peroxide. The mix is cut into discs, into which one imprints the negative halves of the originals and the runner system. The discs are cured at >160 °C and are then ready for use.
The glass is held in place by applying adhesives, elastomeric profiles and rigid structural elements.
This technology is related to mould making as one makes multiple copies out of an original.
3.9.3 Building
24
Silicone Elastomers
4 Composition and Function of Silicone Elastomers
•
heat stable almost indefinitely up to 180 °C in hot air, with special additives up to 250 °C and for a short term even to 350 °C!
4.1 Introduction and Classifications
•
All silicone elastomers consist of crosslinked polydimethyl siloxane (PDMS) molecules, fillers and additives.
transparent: also addition curing grades without yellowing
•
compliant with food regulations such as BgVV, FDA, etc.
Tentatively, apart from the curing temperature, the differences between RTV, HTV and LR are the molecular mass of the raw materials, as indicated in Table 18.
•
sterilisable by gamma irradiation, steam and ethylene oxide
•
very low compression set at elevated temperatures
Similar amounts of fillers are used in general. All silicone elastomers typically contain between 0% and 40% fillers. The bulk of this is fumed silica with surface areas between 150 and 300 m2/g. Fillers are responsible for the mechanical and flow properties.
•
low flammability, non toxic combustion products
•
unique electrical insulating properties, high dielectric strength >20 kV/mm (1 mm test slab), high volume resistivity of approximately 1015 Ωcm
So-called inactive fillers do not reinforce the elastic silicone network. They are widely used in order to improve certain chemical or thermal properties. Examples of such fillers are ground quartz, diatomaceous earth and chalk. Too high levels of such inactive fillers result in loss of the excellent mechanical properties of most silicone elastomers. However, loads of up to 100 parts per 100 parts rubber are occasionally used in order to make the silicone compound cheaper. This latter degree of filling is not advisable, as the resulting compounds behave more like elastic rocks than elastomers.
•
high durability
•
good mechanical properties
•
unlimited pigmentability, etc.
It goes without saying that a high degree of filling results in very high densities and thus a high weight per part.
Table 19 shows some of the mechanical properties of a typical HTV elastomer for various temperatures.
4.2 Properties of Silicone Elastomers The generally advantageous properties of silicone elastomers are as follows: •
Most silicone elastomers possess these general properties. Their most unique property, however, is the comparatively constant elastic properties between -40 °C and +180 °C. No other organic or inorganic elastomer is capable of maintaining its properties over such a wide temperature range, except for fluoroelastomers, which seem to have comparable stability in terms of working temperature.
flexible in the cold down to –40 °C, in special, extreme cases –55 °C
Table 20 gives a rough comparison between the performance of silicone elastomers and some other rubbers. Table 21 gives a comparison of the properties at different temperatures of EPDM, a silicone elastomer and a natural rubber (NR).
Table 18 Polymer viscosity as an estimate of molecular mass for the 3 main groups of silicone elastomers Polymer viscosity (Pas)
PDMS chain length (number of SiO2 units)
HTV - Solid
20,000
6,000
RTV-1 and RTV-2 - Liquid to paste-like
0.1-20
<800
LR - Paste-like
5-100
<1,000
Silicone elastomer
25
Silicone Elastomers
Table 19 Tensile strength, elongation at break and tear resistance of a HTV silicone rubber (ELASTOSIL® R 401/50) at various temperatures Temperature (°C)
Hardness (Shore A)
Tensile strength (N/mm2)
Elongation at break (%)
Tear resistance (N/mm)
200
50
3.3
370
6.7
150
50
5.1
450
8.4
70
50
8.0
63 0
14.0
23
50
10.3
800
18.4
0
51
11.3
870
24.4
–40
53
14.8
910
39.8
Table 20 Qualitative comparison between some commonly used elastomers Fully automatic production
Waste free production
Chemical resistance
Cold flexibility <–40 °C
Heat stable >200 °C
Pigmentable any colour
Thermoplastic elastomer (TPE)
++
++
+/-
-
-
+
EPDM
+
-
+/-
-
-
-
Natural rubber
-
-
-
-
-
-
Polyurethane
+
+
+
-
-
++
Silicone rubber
++
++
+
++
++
++
++ very good, + good, - poor
Table 21 Properties of a silicone rubber (ELASTOSIL® R 401/40) in comparison to EPDM and natural rubber (NR) at different temperatures 25 °C
100 °C
150 °C
Hardness (Shore A)
Tensile strength (N/mm2)
Elongation at break (%)
Tear resistance (N/mm)
Tensile strength (N/mm2)
Elongation at break (%)
Tear resistance (N/mm)
Tensile strength (N/mm2)
Elongation at break (%)
Tear resistance (N/mm)
EPDM
42
15.4
670
17
9.8
270
-
5. 0
200
-
NR
37
15.2
610
42
9.4
330
15
5.0
210
10
401/40
40
9.6
720
22
8.5
530
17
7.6
490
11
Material
4.3 Chemistry and Curing Mechanisms of Silicone Elastomers Silicones and silicone elastomers originate from 'sand'. Even though this is not as simple as it sounds, the complex chemistry and versatile properties of silicones are ‘built on sand’, as shown in Figure 6.
26
Figure 7 shows a schematic overview of the processing and product groups for silicone elastomers.
Silicone Elastomers
Figure 6 Schematic of the production of silicone elastomers
Figure 7 Products and processing technology for silicone elastomers
5 Room Temperature Vulcanising Silicone Elastomers 5.1 General Many RTV systems are widely used as silicone sealants or adhesives. However, their individual function is not typical of the application of silicone elastomers. It is more related to sealants used in structural glazing and in the building industry. In silicone elastomer technology these systems are used
for joining silicone profiles and moulded parts. The applications of such adhesives range from building to healthcare and from automotive to aerospace. However, these materials are excluded from discussion in this review as this would be beyond its intended scope. RTVs with clear elastomeric functions are materials that act as static or dynamic parts, e.g., gaskets, prototypes and mould making aids. RTVs are also used to produce moulded parts, e.g., electrical insulators for medium and high voltage.
27
Silicone Elastomers
5.2 Condensation Curing RTVs
•
In most cases RTV systems are condensation curing. The curable composition is formed by mixing two components, or in the case of one component systems (RTV-1) it is ready to use and it will cure after its application out of the packaging. The major part of the curing system is a PDMS (polydimethyl siloxane) polymer with terminal hydroxyl groups and a reinforcing filler. As additives it contains a crosslinker, usually a functional silane, and a catalyst, in many cases a tin complex.
Retardation of cure occurs if there is a lack of moisture in the rubber or the ambient atmosphere.
The mechanism of condensation curing is illustrated in Figure 8. In this curing process a silicone polymer with terminal hydroxyl groups reacts with a crosslinker with at least 3 alkoxy, carboxyl, amino or oxime groups in the presence of moisture. Organotin complexes act as catalysts.
5.3 RTV-1 for CIPG and FIPG
The curing systems are classified by the chemical nature of the split products formed during the condensation process, when the functional silane is incorporated into the polymer network splitting off the condensation products.
RTV-1 systems often find applications as gaskets. The gasket technology is termed Formed-In-Place-Gasket (FIPG) and Cured-In-Place-Gasket (CIPG). Most typically RTV-1 systems are used as FIPG materials. They are used in automotive applications in order to seal engine segments such as the lubricating and cooling regions of the engine.
Table 22 shows examples of the current most frequently used curing systems, classified according to their acidity – acidic, neutral or basic.
The rheology of these RTV-1 sealants allows for fully automatic application with a low degree of waste, simple substrate treatment and design.
Such systems cure in the presence of air moisture. As they form split products during their cure, such materials exhibit shrinkage with increasing degree of curing.
Once cured, the CIPG gaskets stick to the substrates and allow for good protection against loss.
The characteristics of a condensation curing system are: •
The reaction is isothermal.
•
The volatile alcohol, oxime, amine, etc., is formed as a condensation product.
•
A mass loss occurs due to the volatilisation of the split product, e.g. alcohol, which results in a ‘chemical’ shrinkage of the cured rubber in the range of 0.2-2 % (linear), depending on the concentration of reactive groups.
•
In FIPG technology the gasket cures after joining the two parts (e.g., flanges) that are to be sealed off. This allows for quite low requirements in respect of dimensions as the sealant adapts itself to the space between the two parts. No special surface treatment of the flanges is required. The use of material is economic. Correctly applied FIPGs help to avoid leakages which could result from inserted gaskets or CIPGs. Table 23 shows the properties achievable with RTV-1 CIPG materials, which are commonly used in automotive and other high performance applications. This serves as an example of media and heat resistance.
In most systems the curing reaction reverts at temperatures exceeding 90 °C if the reaction is incomplete.
Table 22 Classification of condensation curing RTV-1 products System
Acidity
Split product
ELASTOSIL® E Acetoxy
Acidic
Acetic acid
ELASTOSIL® N Oxime
Neutral
Oxime
ELASTOSIL® N Alkoxy
Neutral
Alcohol
ELASTOSIL® A Amine
Basic
Amine
28
Silicone Elastomers
Figure 8 Reaction mechanism of the condensation curing process of RTV-1 or RTV-2 systems
CIPG and FIPG techniques are also used across other areas, for example in steam iron gaskets. The requirements are similar to those of the automotive areas.
Acetoxy systems are widely used as so-called general purpose adhesives. Table 25 provides a rough overview of RTV-1 adhesive or coating systems to illustrate the variety of properties and products.
5.4 RTV-1 for Baking Tray Coatings These RTV-1 systems are applied by spraying, their rheology is adjusted to give a low viscosity. Typically, one would use acetoxy systems, such as the example described in Table 24. Baking trays are used at elevated temperatures. The RTV coating acts as a heat stable release agent. (Silicone oils and emulsions are also used as release agents in the tyre industry.)
5.5 Adhesive RTV-1 Materials
As indicated in this table viscosities range from 500 mPas up to several 100,000 mPas, the latter in the case of non sag materials. Non sag materials are required in order to fill wider gaps or to allow for the application of a cord or profile shape onto a substrate, the shape of which is stable before and during the cure. Low viscosity adhesives are desired if the processor needs an easily spreading or a sprayable material.
This area is somewhat related to FIPG/CIPG. FIPG sealing techniques can also be used as adhesive technology in various application areas.
29
Silicone Elastomers
Table 23 Heat and media resistance of an acetoxy type RTV-1 ELASTOSIL® E 14 red (heat stabilised)
Material
Time at 250 °C
Heat resistance Hardness (Shore A) Tensile strength
(N/mm2)
Elongation at break (%)
0 weeks
8 weeks
12 weeks
26 weeks
52 weeks
38
30
30
32
40
2.8
0.8
0.6
0.6
1.2
320
170
160
150
13 0
ELASTOSIL® E 4
Material
Time exposed to MEG:Water 1:1 at 108 °C
Coolant resistance
Hardness (Shore A) Tensile strength
(N/mm2)
Elongation at break (%)
0 days
10 days
45
35
3.7
2. 8
230
27 0 Time at 150 °C
Oil resistance
IRM 902
IRM 903
3 days
7 days
14 days
45
40
39
40
3.7
3. 9
3.2
3.6
230
200
16 0
21 0
45
34
30
29
3.7
2.7
2.3
2.1
230
230
190
22 0
IRM 902 and IRM 903 are standard oils, MEG = monoethylene glycol
Table 24 Typical properties of a baking tray coating material (ELASTOSIL® E 60) Acetoxy type RTV, BgVV compliant, heat stabilised, sprayable, low viscosity ELASTOSIL® E 60
General RTV-1 systems
32
10-60
2.5
0.5-8
250
200-1000
Skin forming time at 50% humidity (minutes)
10-20
>3
Curing time at 50% humidity (hours)
12-24
>6
Density as cured (g/ml)
1.13
0.9-1.5
Hardness (Shore A) Tensile strength
(N/mm2)
Elongation at break (%)
30
Silicone Elastomers
Table 25 General properties of standard RTV-1 adhesives Hardness (Shore A)
Viscosity (mPas)
Material example
Curing system
16
High, non sag
ELASTOSIL® E4
Acetoxy
25
10,000, flowable
ELASTOSIL® N10
Oxime
32
High, non sag
ELASTOSIL® N189
Oxime
20
500
Dispersion T84 (speciality product)
Amine, cures in presence of CO2 and moisture
Solvent based, sprayable, rapid cure
55
High, non sag
SEMICOSIL® 989/1 K
Addition curing, 1 component
Heat curing, high hardness
Application example
Housings FIPG/CIPG General purpose adhesives
pollutants from the environment, as would be the case with addition curing materials.
5.6 Condensation Curing RTV-2 Systems To obtain stable systems, it is imperative to split up the rubber constituents into two components in such a way that unwanted reactions will not occur during their storage.
5.7 Mould Making Condensation Curing RTV-2 Materials
Condensation-curing rubbers consist of a rubber base and a curing agent (hardener, catalyst). Polymers, fillers, softeners and some additives are normally contained in the rubber base, whilst crosslinkers and tin catalysts, as well as extenders and dyes or pigments (if added for visual mixing control), are comprised in the curing agent.
One of the main applications of 2-component RTV systems is mould making. The curing agent is a liquid or paste which is incorporated into the mould making base. Once mixed the system will cure, if enough moisture is present in the ambient air or the mix itself. The preferred curing system is alkoxy based, i.e., the split product is an alcohol.
Even though condensation curing systems seem to be outdated they are still a widely considered option. For example, the curing reaction is hardly inhibited by
Table 26 provides us with an overview on commonly used mould making RTV materials and their properties. It can be quite difficult to pick the right material for a
Table 26 Summary of general purpose mould making condensation and addition curing materials (bold letters highlight the most important properties of each material) Tensile strength (N/mm2)
Elongation at break (%)
50
4.5
230
>10
0.2
250,000
55
4.5
170
>7
0.4
Pourable, soft
25,000
23
2.5
250
>3
0.7
M4440
Pourable, hard
25,000
37
2.0
200
>3
0.4
M4503
Pourable, soft
40,000
25
5.0
350
>20
0.5
M4514
Pourable, soft
25,000
25
4.5
450
>25
< 0.4
M4600A/B Addition
Pourable, soft
15,000
20
7.0
800
>20
< 0.1
M4601A/B Addition
Pourable, soft
15,000
28
6.5
700
>30
< 0.1
M4642A/B Addition
Pourable, hard
15,000
37
7.0
550
>30
< 0.1
RTV material (ELASTOSIL®)
Use
Viscosity Hardness (mPas) (Shore A)
M1470
Kneadable
1 06
M2471
Spreadable
M4400
Tear Shrinkage resistance (% ) (N/mm)
31
Silicone Elastomers
given application. This is why mould makers rely on selection guides and technical service as provided by raw material suppliers.
The heat stabilised materials of Table 27 are also heat conductive, which allows the replica to cool off more quickly.
5.7.1 Speciality Mould Making RTV-2 Materials
5.8 Condensation Curing RTV-2 Compounds for Encapsulation
Material selection essentially depends on the moulding technique, the geometry to be duplicated (undercuts, etc.), the required chemical resistance and mechanical properties of the silicone material.
These materials are used for encapsulation of electric or electronic components. They have low viscosities (900-10,000 mPas) with good dielectric, i.e., insulating properties, as summarised in Table 28. They require between 2% and 10% catalyst/ hardener.
Table 27 provides an overview of speciality materials and their properties. In most cases copies are being made of other pourable systems, which are either chemically aggressive or hot, etc.
Table 27 Summary of some speciality mould making condensation and addition curing RTV-2 materials (bold letters highlight the most important properties of each material) Tear Shrinkage resistance (%) (N/mm)
Viscosity (mPas)
Hardness (Shore A)
Tensile strength (N/mm2)
Elongation at break (%)
M3502
Spreadable for skin moulds Polyurethane (PU)/epoxy resistant
>106
26
4.5
45 0
>23
0.4
M4470
Pourable, heat stable
10,000
60
4.5
120
>4
0.8
M4370 A/B Addition
Pourable, heat stable
8,000
55
3.0
130
>4
< 0.1
M4644A/B Addition
Pourable, self release PU/Epoxy resistant
50,000
40
5.5
400
>25
< 0.1
RTV-2 material (ELASTOSIL®)
Use
Table 28 Condensation curing RTV-2 elastomers used for encapsulation Elongation Tear Heat at break resistance conductivity (%) (N/mm) (W/mK)
Viscosity (mPas)
Hardness (Shore A)
Tensile strength (N/mm2)
General purpose, hard
15,000
55
4.5
120
5
0.55
RT 563
Low viscosity, hard
5,000
55
4.5
120
3
0.35
RT K
General purpose, medium
12,000
45
2.0
130
3
0.3
RTV-2 compound (ELASTOSIL® RT)
Use
RT 426
32
Silicone Elastomers
Table 29 Condensation curing RTV-2 elastomers used for adhesives and sealants RTV-2 elastomer Use (ELASTOSIL®)
Viscosity (mPas)
Hardness (Shore A)
Tensile strength (N/mm2)
Elongation at break (%)
Tear Heat resistance conductivity (N/mm) (W/mK)
RT 480
Spreadable, hard
350,000
55
4.5
170
8
0.3
RT 770
Non sag, heat stable
500,000 A 130,000 B
50
4.0
150
3
0.3
RT 772
Flowable, heat stable
20,000 A 130,000 B
45
2.0
130
3
0.3
5.9 Adhesives and Sealants Based on Condensation Curing RTV-2 Compounds Condensation curing RTV-2 adhesives are less common than addition cured adhesives. This has to do with the fact that there are numerous RTV-1 systems with a good processing time.
The curable composition contains polydimethyl siloxane polymers with terminal and/or non terminal vinyl groups. As a crosslinker a polydimethyl siloxane polymer with Si-H groups is added. The system starts to cure, once a platinum compound is added as a catalyst. An inhibitor regulates the rate of the curing reaction.
They are used in FIPG technology, in particular where inhibition (e.g., by amines, sulfides or organic acids) limits the use of Pt-curing technology (Table 29).
Such compositions often contain a reinforcing filler, e.g., fumed silica with surface areas of 100 to 400 m2/g, allowing for good mechanical properties of the cured mixture.
5.10 Addition Curing RTV-2 Systems
As indicated in Tables 26 and 27 addition cured systems exhibit a number of advantages in mould making. One would expect that these advantages are also present in the case of encapsulating, potting or adhesive RTV-2 systems.
Such systems are mainly two component materials, because the reactive constituents, which allow curing at room temperature with no split products and no external reactant (such as air moisture as mentioned in condensation curing) need to be kept separate. Most common addition curing RTV systems are available in mixing ratios of 1:1, 9:1 or 100:1. Variable mixing ratios are possible. Usually the reaction is very fast, once the two components are mixed. The processor has to use the mixture within a certain time period. This time is called pot life. Once pot life has expired it is no longer possible to process these materials correctly. As the curing reaction is not accompanied by the formation of any split products addition cured elastomers do not exhibit shrinkage upon curing, which leads to easy control of shapes and dimensions. Furthermore such systems are practically odourless. The principle of the addition reaction is shown in Figure 9. The same mechanism is typical for addition cured LR and HTV compounds.
This is the case because such materials are widely used in industrial mass production, where cycle times (i.e., times to produce one unit) and precise dimensions are a must. The latter is better met with addition curing materials as they do not shrink upon cure, whereas substantial shrinkage is found using condensation curing materials. A clear plus is the absence of split products as formed in the curing process of condensation cured materials (and peroxide cured HTV, as described later). A disadvantage is the possibility of cure inhibition, if amines, sulfurous or other catalyst poisons deactivate the Pt catalyst. Viscosity values range from well below 10 Pas to 50 Pas and above. Above 10 Pas the mechanical properties such as tear resistance, tensile strength and elongation at break are quite good, whereas these values are less at very low viscosities.
33
Silicone Elastomers
Crosslinker Polymer chain end
CH3 O
Si
O CH = CH2 + H
Si
CH3
Pt catalyst
O
CH3
CH3 H3C
Si
H + H2C = CH
O
Si
O
CH3
O
CH3 O
Si
CH2
Si
CH2
CH3
O
CH3
CH3 H3C
Si
CH2
O
CH2
Si
O
CH3
Rubber
Figure 9 Reaction mechanism of addition curing RTV-2 silicone rubber systems
RTV-2 systems with high viscosity (50 Pas) can be designed as sponge formulations with moderate mechanical properties.
method. This hardness measurement involves a cone which is immersed into the gel. The depth of this penetration is recorded, and it provides the value for the hardness of the gel.
5.11 Silicone Gels
Silicone gels are widely used in healthcare, electronics and automotive areas. Applications range from damping gels in sporting goods, operation pads and encapsulated electronic components such as integrated circuits to rain sensors, etc.
Silicone gels are addition curing RTV-2 systems, upon curing they form an elastomeric network with a gellike consistency. By varying the mixing ratio it is possible to adjust the consistency of the gel from nearly liquid to hard. As these gels tend to be very soft, their hardness is not measured in Shore A units but using the penetration
34
While allowing for a wide range of hardness, the mechanical strength of the gels is very poor. Their transparency, however, is excellent because of the absence or very low content of filler(s).
Silicone Elastomers
5.12 Addition Curing Systems for Mould Making
5.13 Addition Cured RTV-2 Systems for Encapsulation
While processing and properties are roughly the same as with condensation curing materials, mould making with addition curing systems has vast advantages. Tables 26 and 27 have illustrated the characteristics of addition curing RTV-2 systems.
These materials range from very low viscosity with standard silicone properties, medium hardness for general purpose applications, to very high density and thus heat conductivity for special encapsulation projects. Most of these materials are mixed in the ratio 9:1, where the small component has a much lower viscosity than the large one.
It goes without saying that these advantages or differences compared to condensation curing systems are also of importance when it comes to applications in automotive, aerospace and household applications. Table 30 shows the fundamental differences between the two curing systems.
Table 31 shows examples of a number of widely used RTV-2 encapsulating materials.
Table 30 Fundamental differences between condensation and addition curing systems for RTV-2 silicone rubbers Condensation
Addition
Components
Rubber base + curing agent
Components A + B
Crosslinker/catalyst
Both part of curing agent
Metering of components
Variable within limits; curing agents with different reactivity available
Mixing ratio must not be varied
Effect of temperature
Relatively small: Long pot life = long curing time Reversion, hence no curing possible at temperatures >70 °C
Large: Long pot life at RT; short curing time at high temperatures No reversion, hence curing possible at temperatures up to 200 °C
Linear chemical shrinkage
0.2%-2%, depending on chain length of polymers and proportion of crosslinker
< 0.1%
Inhibition of cure
Lack of moisture
In different components
Various widely used substances
Table 31 Addition curing silicone elastomers used for encapsulation technology RTV-2 material type Use (ELASTOSIL® RT)
Viscosity (mPas) (A/B 9:1)
Hardness (Shore A)
Tensile strength (N/mm2)
RT 601
General purpose, high strength
5,000/40
45
7.0
100
3
0 .2
RT 607
Flame retardant
12,000/200
55
3.5
100
4
0.55
RT 675
Heat conductive
40,000/30,000 (A/B, 1:1)
80
2.0
50
8
1.20 (density 2.3 g/ml)
SilGel® 612
Silicone gel
1,000/1,000 (A/B, 1:1)
Gel
-
-
-
Elongation Tear Heat at break resistance conductivity (%) (N/mm) (W/mK)
0.20
35
Silicone Elastomers
Table 32 Some addition curing silicone adhesives Viscosity (mPas) A/B 9:1 or 1K
Hardness (Shore A)
Tensile strength (N/mm2)
General purpose adhesive or sealant, non sag
10,000 1K
45
3.0
200
3.3
Flowable, also for encapsulation
4,000/ 4,000
45
3.5
100
-
RT system (ELASTOSIL®)
Use
RT 705
RT 741
5.14 Addition Cured RTV-2 Adhesives and Sealants Low viscosity is no longer desirable in the case of adhesives. They should exhibit a certain rheological behaviour allowing for their proper application onto the substrate(s) that have to be glued together. These adhesives are called RTV-2 systems for historic reasons, as they are actually high temperature curing. Characteristic curing times range from 5 minutes at 150 °C to 1 minute at 200 °C, the latter also allowing for a substantial pot life at room temperature. Table 32 shows some properties of silicone adhesives. One component materials are marked 1K. Non sag adhesives are also suitable for FIPG and CIPG technology.
Elongation Tear Heat at break resistance conductivity (%) (N/mm) (W/mK)
0.35 0.50
These foams can be used in multi-purpose applications, and, they can be applied in sheets, strips or cords, all of which are fairly easy to produce, allowing for a very uniform and closed cell structure. These foam compositions allow the production of soft gaskets which are compressible. In silicone elastomer gasket technology this is a breakthrough as even the softest silicone gel is nearly incompressible.
5.15 Addition Cured RTV-2 Foam for Compressible Gaskets
Addition cured silicone foams have to develop a gas as they start to cure. This is usually hydrogen, developing from a second reaction of the siliconhydrogen groups which take part in the hydrosilylation crosslinking process. This reaction takes place in the presence of hydroxyl groups which are present in the formulation.
The latest generation in gasket materials are silicone foams which were derived from RTV technology. The processors aim for silicone properties and, at the same time, for weight reduction and/or for low heat conductivity.
As in other RTV-2 systems the foams are designed to be self levelling or non sag, the latter allowing for use in Formed-In-Place-Foamed-Gasket (FIPFG) technology.
Table 33 Addition curing foams Addition curing silicone foam (ELASTOSIL® SC)
Use
Closed cell portion (%)
Hardness (Shore A)
Tensile strength (N/mm2)
Elongation at break (%)
Density (kg/m3)
SC 833
Flowable, flame retardant
80
27
5.0
80
500
S C 835
Flowable
80
22
4.5
80
500
SC 860
Flowable, low density
80
8-10
2. 5
70
300
SC 870
Non sag, low density
80
8-12
3. 5
100
300
SC 880
Flowable, ultra low density
50
-
-
-
180-300
36
Silicone Elastomers
The applications are in all areas such as automotive, aerospace (seat components), building industry (flame retardant cable bushings) and mouldings, using self levelling foams that are poured into moulds of the required shape. The mixing ratios are 1:1 and variable in many cases. The foam densities are as low as 300 kg/m3, or lower in special cases as shown in Table 33. As these materials develop some amounts of hydrogen during the processing, sufficient ventilation must be supplied for safety reasons.
where large series need to be produced and the cost per piece is a big issue. To a certain extent their use is highly competitive against RTV and HTV solid silicone rubber, even in case of applications in the transmission and distribution industry, such as medium and high voltage cable accessories and smaller insulators. This is due to the short curing time and available processing technology, allowing for an utmost degree of automation and almost waste free production.
6.2 Curing Mechanism of Liquid Silicone Rubbers
In order to apply foams such that they stick to surfaces, one has to use silicone primers in the same way as with conventional techniques for silicone rubber bonding.
All liquid silicone rubbers are addition curing. They cure at elevated temperatures and their main use is in silicone mouldings produced by injection moulding, and textile coatings.
The curing mechanism is the same as for the addition RTV-2 systems (see Figure 9). The mixing ratios of the single components vary from 1:1 to 100:1 in the case of RTV-2, whereas liquid rubbers are most typically 1:1 systems. The difference in the compositions is such that the catalyst (A component; Pt-complex) and inhibitor levels (A and B components; alkyne alcohol) are set in order to provide virtually no curing at room temperature, and high speed of curing at elevated temperatures (for example, when the cold material hits the hot walls of the mould during the injection moulding process).
The scope for application of liquid silicone rubbers is huge (a.8) (49). In injection moulding they are used
Figures 10, 11 and 12 demonstrate the curing characteristics for liquid silicone rubber.
6 Liquid Silicone Rubber 6.1 General
Figure 10 Non isothermal curing characteristics of an addition-cured LR and a peroxide-cured HTV silicone (linear scan at 10 °C/min)
37
Silicone Elastomers
Figure 11 Isothermal curing characteristics of a LR. Curing times of ELASTOSIL® LR 3003/50 at different temperatures.
Figure 12 Pot life of a LR as a function of temperature. Viscosity of the AB mixture of ELASTOSIL® LR 3003/50 as a function of time and temperature (Brookfield viscometer)
Please note that a noticeable degree of curing only occurs after 70-100 hours from mixing A and B at room temperature. This time changes to ‘indefinitely’ at –20 °C and ‘seconds’ at 180 °C, respectively.
Liquid silicone rubbers have been on the market for 30 years with annual growth rates of +10% and higher. Such materials have undergone several innovative changes, especially over the past 10 years. These changes relate to specifications and curing speeds, etc.
6.3 Standard Liquid Silicone Rubbers
The purpose of new fast curing materials compared to standard grades is to reduce the cost per piece, which results from shorter cycle times during processing. These liquid rubbers not only have the same specification but also they are chemically identical to their older predecessors after post cure. Table 34 shows
Standard liquid silicone rubbers originate from general requirements that have evolved from the markets for silicone elastomers over the past 25-30 years. These products are also known as general purpose LR.
38
Silicone Elastomers
Table 34 Comparison between fast curing and standard LR grades ELASTOSIL® LR
t90-values at 130 °C (s)
t90-values at 150 °C (s)
t90-values at 170 °C (s)
Standard, general purpose (GP)
3003
50
38
26
Fast curing, general purpose (GP)
3004
38
27
24
Fast curing, no post cure (NPC)
3005
39
27
24
Standard, oil bleeding, NPC
3089
40
38
26
Fast curing, oil bleeding, NPC
3080
39
31
28
Fast curing, oil resistant, NPC
3013
33
25
23
Fast curing, low flammability
3001
33
22
17
Liquid rubber type
examples of the materials available comparing fast cure and standard grades of LR. Fast curing technology allows the processor to choose a lower moulding temperature to achieve the same or still shorter cycles as with a standard material. This is emphasised by the bold letters in the table. Fast curing LR compositions also provide a new and very interesting possibility, comoulding with thermoplastics. Standard LRs are specified by original equipment manufacturers in automotive, healthcare and domestic appliances. The typical hardness range for standard liquid silicone rubbers is between 10 and 80 Shore A.
for latex products, which possibly still account for more than 60% of elastomeric baby feeding applications. High tear LR is continuously being used to substitute solid silicone offsets and also organic rubbers. Most of these substitutable materials have quite high mechanical strength which is of importance either in the application, for material approval by original equipment manufacturers (OEMs), and/or during processing such as demoulding or assembly, etc. Table 35 shows a comparison between the tear resistance of high tear LR and HTV (a general purpose HTV would be similar to standard LR) (a.9).
6.4.2 No Post Cure LR 6.4 Speciality LRs 6.4.1 High Tear LR High tear resistant LRs were initially developed in order to provide maximal mechanical strength to baby soothers and baby bottle nipples. Today’s global market for such applications is easily beyond 1,000 tonnes per year, and it is characterised by significant growth as a replacement
Standard liquid rubbers allow for a relatively low compression set. This is achievable only after post cure. Compression sets as low as 10% or even lower are possible. Without post curing such materials will have a compression set of 70%. As the process of post curing is energy intensive and substantial lowering of the compression set is usually achieved after 6 hours at 200 °C consuming up to 125
Table 35 Tear resistance for LR and high tear HTV Addition cure LR (Elastosil® LR 3004/50) Tear resistance as measured by ASTM D 624 (N/mm)
High tear LR (Elastosil® Addition cure HTV LR 3043/50) (Elastosil® R plus 4020/60)
25
45
Up to 55
Test slab thickness 2 mm press cured for 5 minutes at 165 °C
39
Silicone Elastomers
Table 36 Comparison between compression sets (25% deformation, 22 h at 175 °C) of post cured (PC) and not post cured (NPC) materials. Duration of post cure 6 h at 200 °C Material type
Compression set
ELASTOSIL®
NPC (%)
PC (%)
LR standard
LR 3003/60
60-70
10-20; max. 35
LR fast curing
LR 3004/60
60-70
10-20; max. 35
LR fast curing NPC
LR 3005/60
15-25; max. 30
10-20; max. 35
LR oil resistant NPC
LR 3013/60
20-30; max. 30
10-20; max. 35
HTV standard
R 401/60
15-25; max. 30
10-20; max. 35
HTV oil resistant NPC
R 701/60
20-30; max. 30
10-20; max. 35
l/kg silicone/min of fresh air, many new liquid rubbers are being formulated to allow for a low compression set even without post cure. These are denoted as NPC. The test method is DIN 53517, 22 h at 175 °C. Table 36 gives a comparison between various grades and their post cured (PC) and no post cure (NPC) compression set (CS). The most common values are shown as a range. See also Figure 5 on compression set. The table is complemented by values for HTV rubbers. Typically, post curing must be applied in all medical and food contact applications. NPC materials are thus limited to technical applications. Most technical liquid rubbers include NPC technology as part of their formulation.
6.4.3 Heat Stabilised LR In many automotive applications it is necessary to use LRs which are heat stabilised. Often, this can be achieved by colouring the rubber with a metal oxide containing pigment paste. As per requirements from suppliers of ignition systems, new grades of LR were developed which are readily stabilised, black and do not require post cure (NPC). They are commonly used in spark plug boots. Table 37 provides a rough comparison between an 80 Shore A hard LR, both stabilised and without additives. A carbon black pigment paste has been used as a stabiliser. Changing to lower hardness, heat stability gets better, the optimum being between 50 and 60 Shore A.
Table 37 Heat ageing of an 80 Shore A LR (ELASTOSIL ‚ LR 3003/80), heat aged for 70h/225 °C with or without a carbon black stabiliser (ELASTOSIL® FL black 9005) LR 3003/80 unstabilised
LR 3003/80 heat aged for 70h/225 °C
Δ (%)
Hardness Shore A
80
82
+2
Tensile strength (N/mm2)
8
5.5
-31
Elongation at break (%)
244
87
-64
LR 3003/80 post cured 4 h/200 °C +4% stabiliser
LR 3003/80 +4% stabiliser heat aged for 70h/225 °C
Δ (%)
77
80
+3
7.9
6.1
-23
259
12 1
-53
Hardness Shore A Tensile strength
(N/mm2)
Elongation at break (%)
Vulcanisation: press cured for 5 minutes at 165 °C
40
Silicone Elastomers
6.4.4 Coolant Resistant LR (NPC) Gaskets for radiators in automobiles are a developing application for LRs. The requirement is to have a gasket of rubber with as little change in properties over time as possible. The rubber gasket has to withstand coolants, usually monoethylene glycol (MEG) in water, at temperatures of above 100 °C and a hot air environment at the outer side of the radiator. Further, the gasket must not embrittle at low temperatures. Traditionally such gaskets have been made of EPDM rubbers. EPDM has better mechanical properties and coolant resistance than silicone elastomers. However, coolant resistant silicone rubbers show the lowest relative change in compression set in hot air and much smaller relative change in other parameters as shown in Table 38.
Such coolant resistant LRs can be used in a number of different, non automotive applications, because they have an increased chemical resistance in general.
6.4.5 Self Lubricating LR (NPC) Such rubbers are also called oil bleeding or oil exuding materials. They are similar in appearance to standard silicones once moulded. After some time they start to form an oily film on the surface of the parts. They are most commonly used in the manufacture of gaskets for electric connectors. The oil film serves as an aid during assembly, and, it improves the hydrophobic behaviour of the seal (this is why the name for the assembled connectors is ‘weather pack’). Typically the oil content ranges between 2% and 7% and the speed and amount of oil bleeding corresponds to these contents.
Table 38 Immersion tests on EPDM, standard and coolant resistant LR Glysantine coolant (G 48/H2O 1:1); immersion time at 110 °C
Hardness Shore A
Tensile strength (N/mm2)
Elongation at break (%)
0d
69
13.8
220
7d
68
13.6
250
+ 0.2
14 d
68
12.9
230
+ 0.5
28 d
68
12.4
220
+ 1.0
42 d
67
12.1
200
+ 1.3
Weight change (Δ Δw) (%)
EPDM Elastomer
Standard LR (ELASTOSIL® LR 3003/70) 0d
73
10.1
330
7d
75
9.6
320
+ 0.4
14 d
75
6.1
190
+ 0.3
28 d
75
5.5
170
+ 0.4
42 d
76
5.5
150
+ 0.3
Coolant resistant LR (ELASTOSIL® LR 3023/60) 0d
62
6.0
280
7d
62
5.0
270
+ 0.2
14 d
62
5.0
270
+ 0.2
28 d
63
5.0
270
+ 0.2
42 d
63
5.0
270
+ 0.5 continued…
41
Silicone Elastomers
Table 38 Immersion tests on EPDM, standard and coolant resistant LR continued Compression set (%) in hot air Time at 130 °C
EPDM
Standard LR (ELASTOSIL® LR 3003/70)
Coolant resistant LR (ELASTOSIL® LR 3023/60)
PC
NPC
7d
16
8
14
14 d
22
12
20
28 d
32
15
25
42 d
45
17
28
Compression set (%) in coolant Time at 110 °C
EPDM
Standard LR (ELASTOSIL® LR 3003/70)
Coolant resistant LR (ELASTOSIL® LR 3023/60)
PC
NPC
7d
12
29
23
14 d
13
46
27
28 d
16
65
32
42 d
21
70
35
The oil (also known as bleed fluid, etc.) is a phenyl polydimethyl siloxane. Because of the content of phenyl groups this oil is not compatible with the matrix of the silicone rubber. As a consequence it migrates freely through the elastomeric network resulting in the formation of an oil film on the surface of the parts (15).
6.4.6 Oil Resistant LR (NPC) Silicone elastomers and in particular silicone rubbers, both solid and liquid have relatively poor resistance when in contact with apolar media such as engine oils and the like. However, it has been possible to formulate liquid silicone rubbers with increased oil resistance. Oil resistance typically is measured at 150 °C for 72 hours. The changes in hardness and mechanical properties again should be as small as possible over time. In addition, because of the apolar character of the silicone network and the apolar composition of engine oils the rubber absorbs part of the oil which causes it to swell. The increase in volume should be as small as possible.
42
The older formulations for oil resistant liquid rubbers contain a passive filler and certain additives. The filler, however, eventually causes problems in mould technology and machinery as it is strongly abrasive. The latest technology allows for non abrasive liquid silicone rubbers with the same oil resistance. Table 39 shows a comparison between standard liquid rubbers and oil resistant LR, both abrasive and non abrasive.
6.4.7 Self Adhesive LR 6.4.7.1 Self Adhesive LR for Technical Applications Self adhesive LRs have been known in the market for some years. However, the name self adhesive indicates that it could be tough to make it stick where desired and yet easy to demould at the same time. Processors helped themselves by teflonising mould surfaces when processing self adhesive liquid rubbers. The advantage for the processor of self adhesive technology clearly is the simplicity of combining plastic with silicone elastomers without using a primer.
Silicone Elastomers
Table 39 Oil immersion tests on oil resistant LR and standard LR (70 h/150 °C) (Figures in brackets denote approximate values for standard LR) Material properties
Hardness (Shore A) Tensile strength
(N/mm2)
Elongation at break (%) Volume swell (%)
Properties after immersion in test oils
Oil resistant, non-abbrasive LR (ELASTOSIL® LR NPC 3015/70)
Standard LR (ELASTOSIL® LR 3003/70)
ASTM I
IRM 902
IRM 903
70
70
66 (67)
63 (65)
56 (47)
7.0
10
7 (6)
7 (6)
5 (4)
230
300
270 (200)
220 (200)
210 (150)
-
-
+3 (+6)
+9 (+12)
+38 (+43)
ASTM I, IRM 902 and IRM 903 are standard oils used for oil resistance testing
The latest, very exciting developments allow the silicone rubber processors to injection mould self adhesive LRs onto substrates with good adhesion. At the same time these materials are easy to demould without the need of release coatings such as teflon (the latter has to be renewed from time to time resulting in undesirable shut downs; also teflon impairs the heat transfer). Adhesion builds up on a time scale which is usually much longer than the moulding cycle alone, as shown in Figure 13. This figure also provides an explanation as to why this new self adhesive material would not adhere to the mould surface.
Table 40 shows a compilation of substrates to which adhesion is possible. With great pleasure the author would also like to point out that it is possible to achieve adhesion on steel inserts without causing problems in demoulding. The only restriction about self adhesive technology is the fact that it is only suitable for technical applications. This has to do with non compliance with the BgVV and FDA (regulations for food contact and medical materials), both of which require post cure in order to reach the prescribed volatile and extractable levels. A post cure at 200 °C over several hours will destroy or at least seriously affect the plastic substrate.
Figure 13 Development of adhesive force over time
43
Silicone Elastomers
Table 40 Some results on adhesion of a self adhesive LR (ELASTOSIL® LR 3070/40) to plastics and metals after press cure for 2 minutes at 185 °C Substrate material MF 152-6021 S1 (melamine-formaldehyde resin)
Supplier / Description
Adhesion
Bakelite
++R
PA 1300G*
++R
PA 1300G black*
++R
PA 1300S*
++R
PA Ultramid A3WG5*
BASF
++M
PA Ultramid B3WG7*
BASF
++R
PA Vestamid L1930
++R
PA Vestamid X7099
++R
PA 4.6 Stanyl TW200F6
DSM
++R
PA 6 Ultramid B3EG6*
BASF
++R
PA 6 Durethan BKV 30*
Bayer
++R
PA 6 Miramid VE 30CW
Leuna
++R
PA 6 Miramid VEP 30C
Leuna
++R
PA 6.6 Durethan AKV 30*
Bayer
++R
PA 6.6/6 Grilon TSM-30*
EMS-Chemie
++R**
PA 6.6 Miramid SE 25 CFM unpigmented
Leuna
++R
PA 6.6 Miramid SE 30 CF black
Leuna
+M
PA 6.6 Reona 1300G
Asahi
++R
PA 6.6 Ultramid A3EG6*
BASF
++R
PA 6.6/6 Grilon BMG-30 HX silver*
EMS-Chemie
++R
PA 6.6/6 Grilon TSG-30*
EMS-Chemie
++R
PA 6.6/6 Grilon TSM-30*,***
EMS-Chemie
++R
PA 12 Grilamid LV-3H*
EMS-Chemie
++R
PA 12 Grilamid LV-5H*
EMS-Chemie
++R
PA 12 Grilamid TR 55*,***
EMS-Chemie
+M
PA 12 Grilamid TR 90*,***
EMS-Chemie
++RM
PA 12 Grilamid TR FE 5512*,**
EMS-Chemie
++R
partly-aromatic PA Grivory GV-5H*
EMS-Chemie
++R
partly-aromatic PA Grivory HTV-5H1*
EMS-Chemie
++R
partly-aromatic PA Ultramid TKR4355G7*
BASF
++R
PBT 5101-G (15%GF)
Toray
++R
PBT C7000LE
-M
PBT (GF) C 7030LN
++R
PBT BT-1015 black-02
DIC
++R
PBT BT-3500 white
DIC
++R
PBT C7030LN
Teijin
++R
PBT H01
Teijin
-M
PBT Pocan B 3235
Bayer
++R
PBT Pocan 4225
Bayer
+M continued…
44
Silicone Elastomers
Table 40 Some results on adhesion of a self adhesive LR (ELASTOSIL® LR 3070/40) to plastics and metals after press cure for 2 minutes at 185 °C continued Substrate material
Supplier / Description
Adhesion
BASF
++R
Mitsubishi Engineering
-M
GE Plastics
-M
PC ‘LISA’
Albis
++R
PC Makrolon 2800
Bayer
-M
PC Makrolon 2805
Bayer
-M
PC Makrolon 2807
Bayer
-M
PC Makrolon 2808
Bayer
-M
PF 31-9005 S 15 (phenol-formaldehyde resin)
Bakelite
++R
PF 7550-9005 S1 (phenol-formaldehyde resin)*
Bakelite
+M
PF 4109-9005 S1 (phenol-formaldehyde resin)*
Bakelite
++R
PMMA***
Röhm
++R
Polyarylamide IXEF 1022/0008
Solvay
++R
PBT Ultradur B4300G6 PC PC Lexan 161R
POM 4520
-M
POM Delrin 100ST
Du Pont
-M
POM Delrin 100T NC10
Du Pont
-M
POM Delrin 500T NC10
Du Pont
-M
POM Hostaform unpigmented
Ticona
-M
-
-M
Mitsubishi Chemical
++R
PP PPE* (m-) PPE X9102** PPO GFN3
+M GE
++R
PPS Fortron 1140L4-1 natural
Ticona
-M
PPS Fortron 1140L4-2 natural
Ticona
-M
PPS Fortron 1140LP4-1 black
Ticona
+M
PPS Fortron 1140LP4-2 black
Ticona
+M
PPS Fortron 6165A4-2 natural
Ticona
-M
-
++R
Dow Chemicals
-M
Aluminium AlMg1
-
++R
Copper SFCuF25
-
++R
Brass Ms58F51
-
++R
Steel V2A
-
++R
PU-coated Aluminium Questra (crystalline polymers)*
Steel 9SMnPb28 Glass
-M -
++R
* substrate dried 1h 100 °C ** results after ageing 1h 100 °C Rating: ++ very good adhesion, + good adhesion, - no adhesion, R rubber tear (cohesion cleavage), M adhesion tear (adhesion cleavage) PA = polyamide, PBT = polybutylene terephthalate, PC = polycarbonate, PF = phenol-formaldehyde resin, PMMA = polymethyl methacrylate, POM = polyacetal, PP = polypropylene, PPE = polyphenylene ether, PPO = polyphenylene oxide, PPS = polyphenylene sulfide, PU = polyurethane
45
Silicone Elastomers
6.4.7.2 Self Adhesive LR in Food and Related Applications The latter facts led to the development of a self adhesive LR which is suitable for contact with food after post cure. However, this would still harm the plastic substrate, although some plastics withstand a post cure at 200 °C, such as PBT. This recently developed LR adheres well to some PBT grades (e.g., PBT Pocan B 3235 of Bayer, PBT Ultradur B4300G6 of BASF). Further, it shows a stronger adhesion to other substrates than with standard silicones. It would go beyond the scope of this article to go into further detail on self adhesive liquid rubbers. For further information refer to Rapra’s Handbook of Rubber Bonding containing an interesting review on the bonding of silicone rubber, or contact the raw material supplier (a.11).
6.4.8 Electrically Conductive (Antistatic Silicone!) LR It is quite remarkable that it is also possible to formulate an electrically conductive LR out of one of the best elastomeric insulators. If a liquid rubber is filled with substantial amounts of carbon black its volume resistivity drops from 1015 Ωcm down to below 12 Ωcm. This is accompanied by a strong increase in viscosity, which rises from approximately 1,000 Pas to 8,000 Pas at a shear rate of 1 s-1 (cone plate viscometer). By varying the amount of carbon black, the silicone supplier is able to provide electrically conductive rubbers in a range of conductivities, as shown in Table 41. Note that the viscosity increases with higher
conductivities. This has to do with the load of carbon black, which is used to make the silicone rubber conductive. The same conductivities can be realised with HTV rubbers. The use is various, it ranges from conductive pills in electronic keypads (standard silicone keypad with conductive pills stuck onto it) to so-called stress cones or deflectors in transmission and distribution (T&D) industries. The latter being an application for medium volume resistivities. Unfortunately, because of the nature of carbon black, it is not possible to achieve resistivities which would just provide antistatic behaviour without making the silicone a good conductor, viz. applying it in volume resistivities of approximately 1,000 to 5,000 Ωcm. This range is not achievable on a basis which is accurate enough to make antistatic parts, this is due to the fact that resistivity rapidly increases by approximately 5 to 8 decades in a narrow range of concentrations (similar to a step function).
6.4.9 Flame Retardant LR Many consumer electronics contain silicone rubber. In most cases standard silicone rubbers are satisfactory with respect to their flammability. However, if it comes to high voltage areas such as TV tubes and the like, the requirements for flame retardancy are raised. This means that the materials must have a limiting oxygen index of at least 27% and a UL94 rating of V0. Table 42 shows the differences between standard LR and flame retardant LR. As mentioned in the applications sections, such rubbers find their applications in anode caps.
Table 41 Volume resistivity of various liquid rubbers/applications Volume resistivity (Ω Ωcm)
Viscosity (Pas at 0.9 s-1)
ELASTOSIL® LR 3003/50
1015
1,000
Medium conductivity LR
POWERSIL® 464
100
2,500
Medium conductivity LR
ELASTOSIL® LR 3163
100
2,500
High conductivity LR
ELASTOSIL® LR 3162
10
8,000
Material type
Name
Standard LR
46
Silicone Elastomers
Table 42 Limiting oxygen indices (LOI) and UL rating for various solid and liquid rubbers (thickness of test slabs 2 mm) LOI
Achievable UL 94 rating
ELASTOSIL® LR 3003/50
23
HB
Flame retardant LR
ELASTOSIL® LR 3001/55
35
V0
Standard HTV
ELASTOSIL® R 401/60
20
HB
Flame retardant HTV, cable grade
ELASTOSIL® R 502/70 C1 MH S1
31
V1
Flame retardant HTV, standard
ELASTOSIL® R 861/70 C1 MH S1
31
V1
Flame retardant HTV, T&D grade
POWERSIL® 310
39
V1
Flame retardant HTV, T&D grade
POWERSIL® 370
30
V0
Material type
Name
Standard LR
6.4.10 Extra Liquid Rubber (XLR®)
6.5 Pigment Pastes
In some applications such as in transmission and distribution or for the manufacture of parts with shot weights of several kilograms, it would be necessary to use injection moulding machines with extremely high clamping force.
Another advantage of silicone elastomers is their pigmentability. Suppliers have a range of pigment pastes permitting almost any colour. The user has to mix these pastes in certain ratios in order to obtain the desired colour. This mix is then added to the silicone rubber via the colour line of the injection moulding machine.
Parts of this size not only exhibit very long filling time during injection but also high internal pressure during the cure (the pressure is a consequence of the thermal expansion of the liquid rubber). Further, the curing times are very long and can easily reach 30 minutes to hours. These difficulties led to the development of extra liquid rubber (XLR®). This material has an extremely low viscosity allowing for a quicker filling step. Also this viscosity allows it to be used in a simple mould which does not require an injection moulding machine. The typical mould temperature generally lies between 100 °C and 130 °C in this latter case. The viscosity is down to 100 Pas compared to 500 Pas in the case of a standard LR.
The pastes deep black, ivory and red iron oxide also act as heat stabilisers. Such pastes essentially contain a vinyl silicone polymer and the pigment. We have already shown the stabilising effect of pigment pastes. It is highly advisable to the processor to use LR and pigment paste from the same supplier where possible. Then the system is stable, whereas in the opposite case the pigment paste could affect the performance of the LR.
7 Solid Silicone Rubber 7.1 General
6.4.11 Other Types of LR It goes without saying, that, at least in theory, one could combine the LR technologies in order to formulate new compositions. This is possible, e.g., in the case of self adhesive silicone rubbers. Examples are: self adhesive, oil resistant LR; and self adhesive, oil bleeding LR.
The consistency of solid silicone rubber is reminiscent of plastilline. Hence, its viscosity is lower than that of organic rubbers. This consistency is such that it is possible to supply solid silicone in almost any shape. The available geometries range from simple strips (as they come off the two roll mill), cords, coils, blocks and profiles to pellets.
47
Silicone Elastomers
In terms of chemistry there is a major difference between RTV and LR. In the first place there is the much higher viscosity. Consequently the molar mass of the polymers which form the elastic network is much higher.
In case of the 100:1.5 system the components are a base and the catalyst. The small component contains Pt whereas the large one consists of HTV rubber base, crosslinker and inhibitors.
Because of this high molar mass, cured HTV usually has a lower crosslink density or at least a different network structure than RTV or LR and thus much better mechanical properties.
The life time of the two components as mixed ranges between 6 hours (for 1:1 extrusion), over 24-48 hours (for 100:1.5 for extrusion), to more than 1 week (for 1:1 moulding).
This mainly holds for peroxide cured HTV rather than for addition cured HTV, the latter exhibiting very high mechanical strength but relatively poor recovery properties (which can often prove to be advantageous).
To date processors seem to prefer 1:1 systems. However, in order to become competitive, such systems will in future be substituted for 100:1.5 or one component systems because of economic advantages and increased flexibility.
Curing mechanisms are restricted to peroxide (Section 7.2.2) and addition cure. No condensation cure is known for HTV silicone rubber.
7.2 Curing Mechanisms of Solid Silicone Rubbers
Currently the preferred curing system is peroxide curing HTV, which is described below. To date processors seem to prefer such systems for various reasons including price. The disadvantages of peroxide cured HTVs are: -
Yellowing after post cure,
-
Smell in production,
-
Peroxide residues in the rubber,
-
Regulatory issues (in case of extrudable HTV),
-
Surface with very high friction coefficient (socalled surface stickiness),
-
Smell and taste issues, and
-
Peroxide split products in the atmosphere.
7.2.1 Addition Cure Please refer to Figure 9 in Section 5.10. What is very much different with addition curing HTV is the fact that it is available both as a one component system, yet exhibiting a considerable life time, and a two component system. The one component system represents the most spectacular recent development available on the silicone market. Unlike LR, these systems are stable between 2 months and even up to 12 months, both at room temperature. The 2 month system is used for extrusion, the 12 month system is used for moulding. Because of some uncertainties during transportation of such uncured rubbers to the processors, the provider will not guarantee any longer than 2 or 3 months after shipment. In the second case, the two component system, the processor will get two separate components which have a considerably longer shelf life. The mixing ratios range between 1:1 and 100:1.5. For the first mixing ratio, component A again contains the Pt catalyst and B the crosslinker and inhibitor(s), the latter being the same as used in LR.
48
Therefore the future of solid silicone rubber is in addition curing technology. Its advantages are numerous and compelling. Today most pharmaceutical applications have switched to the use of addition cure technology, with the following benefits: -
No yellowing, even after post cure,
-
Smell free, cleaner production,
-
Very dry surface,
-
Easy to demould, no air inhibition,
-
High transparency,
-
High tear and tensile strength,
-
No post cure necessary, and
-
No peroxide split products or remainders in the rubber.
Silicone Elastomers
The fact that it is possible to pelletise solid silicone rubber opens up a very wide spectrum of possibilities for automation (which also holds for peroxide cured systems). Another beauty of addition cured technology is the absence of peroxide split products. Hence, a post cure is not necessary for many applications. However, the latter is obligatory if one wants to reach compliance with FDA, BgVV, or to produce cured goods to go into medical devices.
7.2.2 Peroxide Cure The most commonly used peroxides are shown, by application, in Table 43.
temperatures (C1 at 155 °C and C6 at 160 °C). Therefore they allow the filling of the mould before curing. They are not suitable for extrusion because they react with ambient air at elevated temperature rather than with the vinyl groups of the silicone rubber. This behaviour is also called air inhibition. Crosslinker E is suitable for extrusion. It splits at >90 °C, and it has a very minute tendency to air inhibition. It is less vinyl specific than C1 or C6. Therefore it is possible to cure a HTV rubber, the polymer of which is pure polydimethyl siloxane. A post cure is needed after the initial cure during extrusion or moulding, if one wants to reach compliance with FDA, BgVV, or to meet medical device specifications, or obtain smell free products with a low content of volatiles.
The function of the peroxides is the same. These peroxides are chemically stable at room temperature. At elevated temperatures their molecules split and provide radicals which cure the silicone rubber. The different chemical structures of the three peroxides determine their use. C1 and C6 split at relatively high
7.3 Standard Solid Silicone Rubbers Standard HTVs are peroxide curing general purpose grades. They originate from the very first HTV grades that were provided to the silicone elastomer markets.
Table 43 Peroxides used in curing solid silicone rubber HTV For moulding (C1) Dicumyl peroxide, as 98% crystals or 40% on CaCO3 (C6) 2,5-(bis-t-butylperoxy-)-2,5-dimethylhexane, as 45% in HTV rubber For extrusion (E) 2,4-dichlorodibenzoylperoxide, 50% in silicone oil
Dosage
Reacts with
0.7% (98%)
vinyl specific
1.2%
vinyl specific
Dosage
Reacts with
1.5-1.8%
vinyl and methyl groups
Table 44 General purpose HTV silicone rubbers (material series ELASTOSIL® R 401/XX; where XX = hardness Shore A, e.g., 401/20) Physical parameter
Range Minimum
Maximum
20
80 (even 90)
1.09
1.22
6
11
200
1,000
Tear resistance (N/mm, ASTM 624 B)
7
25
Compression set (%)
-
50
Hardness (Shore A) Density (g/ml) Tensile strength
(N/mm2)
Elongation at break (%)
Dielectric strength (KV/mm) Volume resistivity (Ωcm)
18-20 1015-1016
49
Silicone Elastomers
However, their spectrum of properties and production routes have been modernised gradually over the past 30 years. Also, the number of available products has increased to a much wider range of hardness. General purpose rubbers usually are essentially suitable for moulding and extrusion. All general purpose materials are transparent. Many of them are suitable for applications across all industries including healthcare.
7.4.3 Extrusion HTV Special technologies are used to provide enough green strength to allow for the extrusion of large silicone rubber profiles. This is specially the case in tubing with large diameters, or building profiles. Please also refer to the section on calendering (8.3.6).
Table 44 shows a rough summary of standard solid silicone rubbers (HTV) and their features.
The main hardness ranges between 60 and 75 Shore A. It is interesting that these products also exhibit advanced mechanical properties in line with the excellent extrusion properties. However, they are less suitable for moulding.
The typical tolerance from lot to lot for the hardness of HTV silicone rubbers is +/- 5 points Shore A.
7.4.4 Cable HTV
There are other novelty or speciality HTV product grades. It is difficult to describe the scope of these rubbers to the full. One section here is also dedicated exclusively to addition curing HTV.
7.4 Speciality HTV (all peroxide)
This is very much related to extrudable HTV. The typical hardness ranges between 65 and 80 Shore A. These grades have been designed for coextrusion onto the copper leads used in the cable industry. Their mechanical properties are such that the insulators are removable as specified by individual cable makers.
7.4.1 High Tear HTV High tear solid silicone rubbers HTV have a hardness range of 30-70 Shore A. Their tear strength is much higher than that of standard grades with a range of values of 40-50 N/mm (ASTM 624 B). These products exhibit slightly lower heat resistance than general purpose rubbers. Also, their use is in moulding, preferably. It should be noted that it is virtually impossible to have high tear strength at a hardness higher than 72 Shore A. Above this hardness, tear strength will drop to approximately 20-22 N/mm.
7.4.2 Economy High Tear HTV Such grades have been developed to cope with the requirements for medium to high tear strength. Their performance is somewhat between standard and high tear HTV. Their main advantage is a high performance mechanical spectrum coupled with cost savings relative to high tear strength products. The tear resistance of such products lies typically between 30 and 40 N/mm (ELASTOSIL® 411/60).
50
HTV silicone rubbers are used in cables because of their excellent electrical properties. The latter being designed into these formulations for the most part. Within the cable grades there are again general purpose and speciality grades, this is summarised in Table 45 and referred to in Section 3.3. Table 45 lists compliance with VDE Standard, VDE0303.
7.4.5 Oil Resistant HTV (NPC) These products are similar in their oil resistance to oil resistant liquid rubbers. Likewise they are no post cure grades as they contain an additive that provides the oil resistance. Such applications, being technical in most cases, they will not require a post cure. Typically the hardness ranges from 40 to 80 Shore A. The technique of reaching the oil resistance is the same as in the case of the respective LRs: special passive fillers and additives enable this oil resistance. Table 46 compares the oil resistance of an oil resistant HTV and a standard HTV. A higher filler content and a higher crosslink density aid oil resistance.
Silicone Elastomers
Table 45 Wire and cable grades of HTV Material type (ELASTOSIL® R)
Description
Notes
510/70
General purpose; VDE; economy grade
For applications with no special requirements
501/65, 75
General purpose; VDE; good mechanical properties
75 Shore A version is flame retardant
502/70
Solvent resistant; VDE; heat resistant
E.g., automotive cables
502/80
High voltage resistance; VDE; high tear
E.g., ignition cables
509/65
Heat resistant (20,000 h at 200 °C); VDE
E.g., cable up to UL 62 class 22
533/60
High wear and tear resistance; VDE
Addition curing, e.g., for instrument and battery cable
Table 46 Results on oil immersion tests (3 d at 150 °C) on an oil resistant HTV (ELASTOSIL® R 701/80 S) in comparison to a standard HTV (ELASTOSIL® R 401/60 S). The oil data for the standard HTV is listed in brackets Standard HTV
Oil resistant HTV
(ELASTOSIL® 401/60)
(ELASTOSIL® 701/80)
ASTM I
IRM 902
IRM 903
Hardness (Shore A)
60
80
77 (58)
73 (54)
62 (35)
Tensile strength (N/mm2)
10
7
7 (9)
7,7 (9)
6,3 (2,1)
Elongation at break (%)
560
220
240 (590)
240 (630)
220 (410)
+4 (+4)
+8 (+8)
+30 (+44)
Volume swell (%)
7.4.6 Electrically Conductive HTV These rubbers are antistatic. For moulding it is possible to use peroxide cured conductive HTV. Its hardness ranges from 50 to 70 Shore A. For extrusion, generally, an addition cured conductive HTV is used. This is because the carbon black required for the conductivity will deactivate peroxides in extrusion. Typical applications would be body electrodes, leads for ignition cables, conductive pills in keypads for consumer electronics, stress cones for transmission and distribution, etc. The same conductivities are achievable as with conductive LR. Again it is impossible to reach an intermediate conductivity of 1,000-5,000 Ωcm precisely enough to provide antistatic but also insulating properties.
Test oil
7.4.7 Super Heat Stable HTV It is very unusual to have freely pigmentable and heat stable HTV. Not in the case of the highly crosslinked super heat stable HTV. This material is heat stable without the need for a further stabiliser. Hence, it can be used at up to 300 °C. With such advantages we also have to accept a limited selection of Shore A hardness and the fact that there are materials with better performance in extrusion. A standard HTV would require a very good heat stabiliser to merely reach this level of stability. This would imply the disadvantage of a loss in pigmentability. The colour restrictions will be to offwhite to pastel colours. Table 47 shows heat ageing results on freely pigmentable, super heat stable HTV. This material lasts up to 7 days at 300 °C.
51
Silicone Elastomers
Table 47 Heat ageing data on a super heat stable HTV (ELASTOSIL® R 750/50) at 300 °C Exposure time at 300 °C
Material property Hardness (Shore A) Tensile strength
(N/mm2)
Elongation at break (%) Weight loss (%)
0 days
3 days
7 days
50
64
74
10
5.8
6.1
550
280
200
-
-7.7
-12.6
increasing aggressivity of steam above this temperature the life time of silicone rubbers decays steeply.
7.4.8 High Green Strength/Coolant Resistant HTV High green strength products are usually good in extrusion. Some of them also are formulated such that they provide good coolant resistance. Recently these products have started being used for turbocharger hoses, as well as radiator hoses. They are the preferred material in the manufacture of fabric reinforced hoses. Their green strength is discussed under the section on calendering (8.3.6).
While standard HTV grades show a life time at 160 °C of 4-5 days (embrittlement and disintegration are the symptoms of destruction), a steam resistant material will last for more than 6 weeks (Table 48).
7.4.10 Heat Conductive HTV
Such compounds will withstand dry steam at more elevated temperatures than standard silicone elastomers.
New heat conductive grades of HTV have been developed. Their use is in rollers and other applications requiring electrical insulation, basic properties of silicone rubber and heat conductivity of up to 1.2 W/mK in extreme cases.
Below 130 °C the steam resistance seems to be equal among most HTV grades. Because of the drastically
A comparison between the conductivities of standard and heat conductive HTV grades is shown in Table 49.
7.4.9 Steam Resistant HTV
Table 48 Properties of a steam resistant HTV (ELASTOSIL® R 755/60) exposed at 160 °C to dry steam Time of exposure
Property
0 days
28 days
56 days
Hardness (Shore A)
60
60
60
Tensile strength (N/mm2)
7.0
4.4
3.5
Elongation at break (%)
320
290
240
-
+0.7
+1.0
Volume change (%)
Table 49 Comparison of heat conductivities of HTV materials Material name
Type
Heat conductivity (W/mK)
ELASTOSIL® R 401/60
General purpose
0.2
ELASTOSIL® R 840/40
Heat conductive
0.55
ELASTOSIL® R 840/70
Heat conductive
1. 2
52
Silicone Elastomers
7.4.11 HTV for Transmission and Distribution (T&D) Applications These HTV grades exhibit outstanding electrical properties. They contain certain anti-tracking additives, fillers (e.g., aluminium trihydrate), etc. As transmission and distribution applications such as insulators work under the severest conditions they require a very resistant material. Apart from all the general advantageous properties of silicone rubber one of the most demanding property requirements is tracking resistance. T&D HTVs exhibit tracking resistance of 3.5 kV to 4.5 kV without a problem. As a reference, standard HTV allows for 2.5 kV only. Further, these materials have excellent resistance to an electric arc and they are highly flame retardant. Also, as silicone rubbers are UV stable, they are the perfect material for outdoor applications, which is documented by experience over the last 30 years.
requirements, which have become stricter with respect to peroxide split products. Recently, the peroxides have been under discussion in Europe, as per likely changes to regulations, in particular for extrusion. Another asset of the addition curing technique is the fact that it allows for nearly smell free production without any residual split products of peroxides. Consequently the as cured articles are considerably cleaner. In addition, their appearance is more sterile, as they do not yellow, and their surface is much drier. The latter also accounts for less stickiness between the silicone parts themselves and also for better demoulding properties. Addition curing HTVs have more advanced mechanical properties as shown in a direct comparison to peroxide curing HTVs in Table 50. This table also indicates a remarkably lower modulus at equal Shore A hardness (this can be guessed from the elongation at break versus tensile strength). Behaviour like this is typical for addition cured HTV in moulding and extrusion.
7.5 Addition Cured HTV 7.5.1 Introduction
7.5.2 Addition Curing
One of the most prevalent disadvantages between HTV and LR has been the speed of curing because of the faster crosslinking reactions for the LR compared to HTV. By changing from peroxide to addition cured HTV this difference has been compensated for or at least diminished.
A distinction is made between one component and two component systems. One component systems can be considered as mixtures of the two component systems (however the ingredients of the mixes have different additives and proportions).
A further motivation for the increased use of addition cured HTV rubbers were the pharmaceutical
One component (1K) systems have a shelf life of 3 to 6 months, whereas the mixes of two components (2K) last for 1 to 7 days.
Table 50 Mechanical properties of addition cured HTV versus peroxide cured standard HTV Name
ELASTOSIL® R plus 4001/60
ELASTOSIL® R plus 4020/60
ELASTOSIL® R 401/60
Type
Addition cured, standard
Addition cured, high tear
Peroxide cured, standard
60
60
60
10
10
11
Elongation at break (%)
800
850
600
Tear resistance (N/mm)
32
43
24
Rebound resilience (%)
53
53
55
Compression set (%)
19
30
15
Hardness (Shore A) Tensile strength
(N/mm2)
53
Silicone Elastomers
Table 51 Overview of HTV grades with addition curing systems Name (ELASTOSIL® R)
Type
Processing
Applications
4000/40-80
Two component (1:1), high tear
Injection moulding, press cure
Medical devices, food contact, high tear
4001/40-80
One component, standard
Injection moulding, press cure
Medical devices, food contact
4020/60
One component, high tear
Injection moulding, press cure
Medical devices, food contact
4070/60
One component, self adhesive
Injection moulding, press cure
Technical applications
4110/40-80
One component
Extrusion
Medical devices, food contact
4305/40-80
Two component (100:1.5)
Extrusion
Medical devices, food contact
533/60
Two component (1:1), wire Extrusion and cable grade
Table 51 gives examples of addition cured HTV grades for extrusion and mouldings, the mixing proportions of the curing systems and some remarks.
Extremely high wear resistance
7.5.3 Moulding: 1K Addition Cured HTV
Essentially two product series have developed. The first complies with most standard applications known for peroxide cured and organic rubbers. The second, a high tear strength series, has been designed to cope with advanced requirements in respect of tear and tensile strength.
This group of materials represents one of the latest developments in silicone rubber technology. It goes without saying that it is quite contradictory if one wants to have a fast curing material while having to stabilise it such that it does not cure at room temperature too quickly.
Remarkably interesting is the fact that 1K HTV allows for the same speed of curing as the equivalent 2K HTV, as shown in Table 52. This table also shows the difference in curing time of peroxide cured HTV and addition cured LR.
This has been achieved by using novel technology for silicone rubber formulations. 1K HTV has also developed from the idea that processors want a readyto-use compound, which they can put into the stuffer box of the injection moulding machine or the press. Time and consequently cost pressure led them to demand a faster cure without increasing the complexity in the processing by having to mix a multi-component system (the latter with a shorter pot life).
As also mentioned under the upcoming processing section, HTV rubber is available in pelletised form (however, there are a few restrictions). For the first time in the history of silicone rubber, this preform of HTV allows for a fully continuous feed not only into extruders but also to injection moulding machines. The latter has been a breakthrough in HTV technology, and, with addition curing and mould technology, HTV processing can be simplified as follows:
Table 52 Comparison of curing times for HTV and LR materials
Curing time 180 °C 6 mm slab (s)
Addition cure LR (ELASTOSIL® LR 3003/50)
Peroxide cure HTV (ELASTOSIL® R 401/60 with 0.7% C1)
Addition cure HTV (ELASTOSIL® R 4000/60 or 4020/60)
25
12 0
50 2- and 1-component
Curing conditions: Injection moulding of a test slab 6 mm thickness, Moulding temperature 180 °C, Cold runner mould
54
Silicone Elastomers
• Fully automatic, • Waste free, • Short cycles.
is degrease and dry it before applying this novel silicone rubber.
This results in low cost per piece. Thus this HTV is much more competitive to organic rubbers and even LR. Such production methods have been demonstrated by LWB and Maplan. For example, an injection moulded tubing connector with a length of 10 cm, inner diameter of 4 cm and wall thickness of 7 mm requires a curing time of only 50 seconds, while needing 180 seconds at 180 °C with peroxide cured rubber (and, of course much longer with organic rubbers). A 200 t ENGEL machine with a special feeding system for pellets was used in this test.
7.5.4 Moulding: 1K Self Adhesive Addition Cured HTV It has been possible to develop a self adhesive HTV which is addition curing and also a one component material. It sticks to many more substrates than self adhesive LRs do (while not sticking to the mould, see Figure 13). The main intention is to provide a self adhesive material which allows for rubber to metal adhesion, easily. As with self adhesive LR this material does not require a primer on the substrate. All the processor has to do
7.5.5 Moulding: 2K Addition Cured HTV Some processors prefer 1 component systems allowing for a storage time of at least 3 months at room temperature. Others, however, prefer to buy two separate components which they can put on the shelf over a year and mix them, when needed. At this point, they have to pay attention to pot life. Anyhow, both concepts have their pros and cons, and I will try to elaborate them in this subsection in Table 53. In general, 2 component materials will provide more degrees of freedom with respect to the internal logistics of a processor: components have a very long shelf life, and there is an increased flexibility as to colour addition and hardness adjustments. As with peroxide cured materials a mix of two grades with different hardness will result in an intermediate value. The relation between the mixing ratio and the resulting hardness is almost linear, as shown in Table 54. The hardness of peroxide curing silicone rubbers can be adjusted in the same way.
Table 53 Comparison of two component versus one component addition curing systems 2 Component
1 Component
Pot life after mixing 1 to 7 d (for extrusion and moulding, respectively) while components have a very long shelf life
Long shelf life up to 3 months
Flexibility to adjust hardness, colour, additives
Ready to use compound
Flexibility in adjusting the curing speed, in particular in extrusion in order to improve extrusion result (raise catalyst from 1.5 to 1.8%)
Hardness not adjustable
Addition of colours allows for variety of goods from the same transparent base
Colour not adjustable
Table 54 Adjustment of hardness of addition curing systems Mixing ratio of two different materials Desired hardness (Shore A)
ELASTOSIL® R 4305/40
ELASTOSIL® R 4305/70
50
66 parts
33 parts
55
50 parts
50 parts
60
33 parts
66 parts
65
17 parts
83 parts
55
Silicone Elastomers
By using a 2 component system with a mixing ratio of 100:1.5 or 100:2 the processors gain further flexibility. Firstly because of more convenient stock management. Secondly, in order to achieve an intermediate hardness it is necessary to mix two large components (instead of 4 as in the case of 1:1 systems). This becomes of more importance when the processor has to mix two different viscosities. Thirdly, it is easier to control the temperature of the mix. In comparison to peroxide cured HTV, mouldable platinum cured HTV silicones cure twice as quickly (in most applications). Hence, the process requires less energy per piece.
7.5.6 Extrusion HTV As with peroxide cured HTV, the curing speed has to be much faster for extrusion than for moulding in order to allow for sufficient cure. This is necessary, as the uncured extruded profile has to remain in shape while passing through the curing tunnel. This shape stability is the green strength. As the temperature of the material rises while passing through the curing tunnel its viscosity drops. The green strength of the material could be destroyed by this drop. A quick speed of curing acts against the drop in viscosity, and it thus assists the stability of the shape of the extruded goods.
7.5.7 Post Curing of Addition Cured HTV It is essential for processors to pay attention to the fact that addition cured products must not be post cured (in some cases not even stored closely) together with peroxide cured extrusions or mouldings. This can lead to discoloration, smell and in extreme cases to severe damage to the HTV articles (the latter if stored in hermetic packaging).
8 Processing Silicone Elastomers
elastomers, which allows us to predict that there will be many new processing technologies within the near future. All silicone elastomers should be stored at moderate temperatures, i.e., between 15 and 30 °C. It is not advisable to keep the stock of silicone elastomers outside of shop floors. During hot periods this leads to shortened shelf life. Too cold a storage leads to condensation of water and thus undesired impact on reactivity.
8.1 RTV-1 Systems RTV-1 materials are supplied in tubes, cartridges, pails, drums and bags. Basically they are pumped from the packaging and applied as indicated on process guides and data sheets. It is imperative to pay attention to the fact that the curing speed will revert into depolymerisation at 80 °C or higher, and, that the user must allow for sufficient contact with ambient air and in particular moisture. This moisture is an essential reactant during the curing step and therefore indispensable. Most materials are pumpable manually or automatically. They are applied by robots and/or spreading systems. Organic solutions of RTV-1 in apolar solvents are easily sprayable. In order to achieve maximum adhesion when using RTV1 as adhesives, there must be intimate contact between the glue and substrate(s). The technical documentation contains hints on processing time, pot life and/or skin forming time. The industrial application process has to be chosen such that processing occurs well before expiry of these process windows. It is highly advisable to take into account the fact that most of the stated properties of the cured rubbers develop a couple of days after the cure to a tack free state. This has to be checked and implemented in the design of the application process prior to mass production.
Because of the wide variety of industries and the vast number of different silicone elastomers, it is not possible to describe all the processing techniques. I will concentrate on the most well established processing technologies for groups of materials in order to give a comprehensive picture.
For RTV-2 systems basically the same process guidelines apply as for RTV-1. However, being 2 component systems much shorter processing times are possible.
Especially in recent years, processors have developed more and more ideas about how to process silicone
In both RTV-1 and RTV-2 processing it is vital to maintain a constant temperature relevant to the process
56
8.2 RTV-2 Systems
Silicone Elastomers
step. The same holds for the humidity in the case of condensation curing materials. The mixing ratios allow for certain tolerances in terms of process characteristics. However, an excess or lack of the components leads to varied speed of curing, embrittlement, stickiness, no cure and the like. Thus it is advisable to provide the correct mixing ratios by accurate operating instructions and personnel training.
In the case of addition curing RTV-2 systems one has to take care that the model does not inhibit the cure. Otherwise one has to apply a coating to the model. It is highly advisable to thoroughly stir pourable RTV-2 silicone rubber components prior to their use to rehomogenise them. The same has to be done with components that have high viscosity with high mechanical properties.
It is also vital to take into account differences in viscosities of the single components. Low viscosity materials tend to stick to the wall of the mixing vessel which can lead to dosage errors. Also thin liquids are best mixed into high viscosity media and not the other way round.
The components should be dosed accurately. Various equipment can be used in metering. Again the equipment must be free of inhibitors if addition curing materials are to be processed.
Uncured paste-like silicone RTV-2 components can contain up to 20% dissolved air, especially if the components are pumped by pressurised air. In such cases the processor has to take care to deaerate them before use, particularly, if the curable mix is heated in order to speed up the curing process. Incompletely deaerated systems tend to form bubbles.
The mix must be homogeneous in order to ensure uniform curing characteristics.
The processing of RTV-2 materials could be described ad infinitum, because RTV-2 processing includes many degrees of freedom and many products. It is impossible to explain everything in one go. The reader is strongly encouraged to refer to literature on the raw materials and also to documentation as supplied by equipment manufacturers. Mould making will be described as an example of the complexity of processing.
8.2.1 Mould Making: Flexible Moulds Mould making (flexible moulds) consists of the following steps (a.10):
Pourable and spreadable products can be mixed by hand with a spatula or, for larger amounts, with a mechanical stirrer or automatic mixing and metering equipment (the latter can be fully automated). Kneadable compounds are mixed on a triple roll mill or in a kneader. To obtain vulcanisates without any air bubbles, pourable grades have to be deaerated in a desiccator or vacuum cabinet at reduced pressure. Spreadable, non sag and kneadable mixes cannot easily be deaerated. In this case, first a thin, bubble-free primer of a pourable grade is applied to the surface of the model followed by the spreadable or kneadable compound. Flowable RTV-2 silicone rubbers are poured over the model, spreadable and non sag compounds are applied using a spatula. Kneadable grades in the form of a sheet are pressed on the model surface by hand or using a roller. With flexible silicone moulds, undercuts can be demoulded by stretching the mould.
•
Make and prepare a model,
•
Get raw materials ready (single components),
•
Meter and mix the components,
Apart from the versatile properties of silicone elastomers, RTV-2 silicone has advantages over organic elastomers in mould making:
•
Deaerate the mix (air is entrapped after storage and during mixing),
•
Easy processing,
•
Make the mould.
•
Extremely flexible when cured and durable,
•
High strength grades are available, which are tear resistant,
•
Excellent release properties, and
•
Relatively safe raw materials compared with, e.g., polyurethanes.
In order to prevent sticking problems the model surface has to be free of porous, moisture absorbing (condensation curing systems!) and silicone/silicate containing surfaces (in particular ceramics, glass, etc.). This can be done by coating the model with polyvinyl alcohol, methyl cellulose, soft soap or Vaseline.
57
Silicone Elastomers
8.2.2 Mould Making: Block Moulds
8.3 LR and HTV
One part block moulds are normally used to copy single sided objects such as stucco, coins, etc. The model is put into a box and covered using flowable silicone, or, it is impressed into a block or strip of kneadable silicone rubber.
8.3.1 Press Curing HTV
This is related to spin casting. It is possible to cut the ready made mould along a parting line in order to allow for better demoulding. These multipart moulds are advantageously made from transparent silicone rubbers. Two-part block moulds can be made by pouring a one-part block mould and cutting it open along a parting line.
In press curing the processor preforms HTV into pieces of the required size and puts them into a hot mould. The two halves of the mould are mounted in a hydraulic press. The press closes and the curing takes place. After the cure the processor demoulds the parts manually. As a post treatment he has to remove flash, which is a result of internal mould pressure and to check the parts for incomplete cure, which is particularly important in peroxide cure technology. In press or compression moulding the processor has to put silicone rubber pieces into each cavity.
8.2.3 Mould Making: Skin Moulds For large models or ones with deep undercuts, a skin mould is the choice with 5-10 mm thickness. Skin moulds require less material but they are labour intensive. Thus the mould maker has to assess the economics of each moulding job. Skin moulds result from pouring or spreading techniques. Smaller horizontal models are best copied using the pouring method. The model is covered with clay or plastilline. The thickness of the spacer determines the thickness of the skin mould. The rigid layer is put on top of the spacer. It is poured (plaster or casting resin) or spread in a few layers (polyester, polyurethane or epoxy resin, etc.). After curing it is separated from the spacer. The latter is no longer needed. The support containing air vents and feeding holes is now put over the model. The silicone rubber is fed through the feeding hole and left until it is entirely cured. After demoulding the model and recombining support and mould, the skin mould is ready to receive the reproduction material. Too large or vertical models are reproduced by the spreading technique. This is a layering method, as described before. A thin primer of pourable silicone rubber is applied to the model. This primer guarantees the copying of fine details of the model. After a partial cure a top layer of non sag silicone rubber is applied using a spatula. The support consists of fabric strips soaked in plaster or a fibreglass-reinforced organic resin. The demoulding stages are identical to those of the pouring technique.
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8.3.2 Transfer Moulding HTV In transfer moulding the mould is equipped with a reservoir into which the processor puts the rubber. Ideally the temperature of the reservoir is well regulated while not affecting the thermal balance of the mould which is located below it. The transfer process has the advantage of being able to provide silicone rubber to multiple single cavities and also to fill moulds that have long flow paths. In transfer moulding one would typically use the same press as for compression moulding. Both, transfer and press moulding are processing techniques most suitable for small series production (or mass production with a wide variety of geometries). However, press curing and transfer moulding will not compete with injection moulding, if it gets to larger scale production. Mould design in these two technologies is less critical than in injection moulding. But it is well known that even in these basic technologies of silicone HTV processing it is a must to obey the ‘rules of silicone’ by applying the correct conditions. In many discussions with processors these conditions have improved the moulding result upon changing these parameters: •
Moulding temperature (not below 160 °C, ideally at 180 °C),
•
Clamping force (as high as possible, variable),
Silicone Elastomers
•
Mould surface (electroeroded, sand or glass pearl blasted; a smooth or polished surface increases stickiness),
•
Mould release agents ONLY if necessary,
•
Internal mould release agents to be avoided where possible,
•
Volume of the parts to be balanced with the force of the press.
directly to the single cavities. The cold runner is temperature controlled up to the tips of the nozzles of the manifold system. It goes without saying that it is difficult to design such mould concepts as it is not obvious how to apply cold nozzles hermetically to hot cavities. This is the trick and the know how of the mould makers. The hot mould is at 170 to 220 °C. The injection volume is kept at room temperature and in some cases up to 60 °C (the latter only in the case of peroxide cured HTV) in order to reduce viscosity. The cold runner will typically heat up to approximately 40 °C. The nozzles of the cold runner are either open or needle operated.
8.3.3 Injection Moulding LR and HTV Injection moulding technology easily outdoes the two latter moulding techniques. It allows for fully automatic processing with essentially no need for personnel. Thus, the human factor is negligible in the outcome of the processing, or at least it is constant, if the settings of the injection moulding machine are kept constant. As in most fully automatic processes the technical requirements for the moulds are stricter than in the previous cases.
8.3.3.1 Injection Moulding HTV In the case of HTV an injection moulding machine is fed via a piston (up to 25 l) which presses the silicone rubber into the barrel of the machine. The screw of the machine takes in the required injection volume while moving backwards. When finished the screw is pushed forward and this volume is injected into the mould. In order to avoid back flow of the material the tip of the screw is equipped with a check valve. The nozzle of the barrel has a needle shut off valve. As the rubber cures at elevated temperatures it should be kept as cold as possible during the injection. This is why a good injection moulding machine allows for good temperature control of the rubber during the metering and injection steps. If the temperature control becomes inefficient, e.g., because of frictional heat, the injected rubber could start to cure prematurely, resulting in filling defects. Hence, it is essential to keep the rubber cold as long as possible during injection while it should cure as quickly as possible after filling the mould. This is achieved by using a cold runner system. This is a manifold which distributes the curable HTV rubber
The injected volume trapped in the cavities heats up while having time to cure. As the silicone heats up it also expands. This is why it exerts an internal pressure to the surface of the mould of up to 500 bar. This pressure has to be compensated for by the clamping force of the injection moulding machine. Oversized moulds (too many cavities and/or too high a cavity volume) result in defective parts. The feeding of HTV into the piston (stuffer box) of course is in contradiction to a fully automatic process, particularly if we also consider the fact that the rubber base has to be mixed with the curing additives on roller mills before being charged. Using advanced moulding technology it is possible to process HTV rubbers completely waste free and fully automatic between two charging cycles. Now, these charging cycles may no longer be relevant. Injection of HTV is at a revolutionary stage of development at the moment. HTV is now available in pellet form. Figure 14 shows the concept of the feeding system which prevents bridge formation (thus blocking by electrostatic charge of the HTV pellets). It is possible to feed the pellets over distances of 20 m out of boxes or vessels of almost infinite size. As a consequence, no storage space is necessary close to the machine. The processing is further facilitated by the fact that it is possible to add pelletised colour masterbatches.
8.3.3.2 Injection Moulding LR Liquid silicone rubber has a much lower viscosity than HTV. This is why the strict requirements as to mould technology are even stricter for LR. The tolerances along parting lines have to be as low as possible. At the same time, as the speed of injection is much faster than with HTV and the viscosity much lower, the cavities have to allow for removal of air.
59
Silicone Elastomers
Figure 14 Feeding system for HTV pellets as used in moulding and extrusion
Furthermore, LR moulds have to work fully automatic upfront, in order to allow for the desired productivity. Because of the speed of curing one also wants to increase the number of cavities in order to allow for a maximum number of parts per cycle (today it is possible to produce up to 256 parts per shot). All these needs and properties require an utmost degree of experience in machinery and mould design. There are approximately 10 mould makers worldwide who know how to construct competitive moulds for LR. As to machinery, the number of machinery suppliers being as small or smaller, the requirements are stricter as well. Because of the increased speed of curing one has to pay attention to the thermal regulation. The low viscosity requires specially constructed check valves at the tip of the screw. Because of their curing mechanism liquid silicone rubbers are two component systems. LRs are supplied as two components with a mixing ration of 1:1. Special pumping units pump the material from drums into a static mixer, which leads the curable mix into the barrel of the injection moulding machine. As in HTV the cold runner will consist of a well balanced manifold system with open or needle shut off nozzles. The maximum numbers of cavities are 256 or 64, respectively.
60
The processing system essentially consists of a pumping unit ensuring a 1:1 mixing ratio of A- and Bcomponents (where component A contains the Pt catalyst and B the Si-H crosslinker), the injection moulding machine (using a static mixer the 1:1 A and B flows result in an intimately mixed curable composition) and a cold runner mould for liquid rubber. In quiescent state the AB mix and also the single components have a paste like consistency. Their viscosity typically ranges from 100 to 8,000 Pas. Once sheared the viscosity drops dramatically. Hence, when pumped the viscosity drops by a factor of 2-4, when injected through the cold runner nozzles the material turns into a liquid with a consistency of syrup. This consistency allows for the use of injection moulding machines with a relatively low clamping force. Preferably this is between 80-100 tons. However, special applications such as high volume articles with a high projected surface require up to 400 tons. The low viscosity also favours long flow paths and complex geometry, the latter with very precise tolerances. Figure 15 describes the processing system. The mould symbol comprises the cold runner and the hot mould. The material is kept relatively cool until the end of the cold runner, when it enters a hot mould.
Silicone Elastomers
Mode of operation of an injection moulding machine. ELASTOSIL® LR is suitable for virtually all metering and mixing equipment, 1 Metering device for Components A and B of the liquid silicone rubber 2 Metering device for pigment (if required) 3 Mixing device 4 Mould 5 Heated injection mould with injection moulding part
Figure 15 Processing of liquid silicone rubbers
The cold runner acts a manifold that allows for the transport of the liquid material directly to the cavities. Its task is to keep the material cold until it enters the hot cavity through the nozzle which is also cooled. In the market for liquid silicone rubber moulds such cold runners can manage up to 128 cavities. The nozzles are either open, or equipped with needle-shut-off valves. Both concepts are widely used and each has its pros and cons.
when designing HTV moulds!), tolerances, and venting during the filling stage, Selection of steel quality. It is essential to use the correct steel which allows for proper demoulding and life time of the mould, Spare parts and after sales service, Training,
It is highly advisable that interested processors contact mould makers specialising in LR processing. Based on drawings and article specifications they provide the best information as to: Thermal separation between cold runner and hot mould, Heating of the mould (this is usually insufficient in less experienced mould makers), Balancing the cold runner manifold in order to provide uniform flow and thus mould filling, Numbers of cavities, Mould design, LR allows for flash free production with no waste at all, Allowing for thermal shrinkage of LR (as shown in Figure 16, please note this is also considerable
Selection of the machine size or adaptation to a given machine specification, Demoulding and other automation aids such as robots, etc., They sometimes also offer packages including everything. It goes without saying that processing liquid rubber is not possible with a machine that is used for thermoplastic injection and/or high consistency rubber. The machinery supplier must be prepared to provide a so-called LIM (liquid injection moulding), package. A typical technical term in this respect is therefore ‘LIM machine’. As mentioned before, there are a few machine suppliers that would be able to provide the knowledge as stated above for mould makers. It goes without saying that experienced machinery and mould makers maintain relationships which prove productive in each project.
61
Silicone Elastomers
Figure 16 Linear shrinkage of LR (ELASTOSIL® LR 3003/50) as a function of moulding temperature and flow directions (a) lengthwise, post-cured; (b) lengthwise, not post-cured; (c) broad-side, post-cured; (d) broad-side, not post-cured
8.3.4 Extrusion of HTV The major processing techniques of solid silicone rubber are 60% extrusion and 40% moulding. A lesser amount is used in calendering and textile coatings. In extrusion, catalysed solid silicone rubber is fed into an extruder designated for silicone processing. Ideally the screw has a core and/or flight progression. As the screw fulfils various tasks such as feeding, deaeration, residual mixing and replastification (the latter is of importance, e.g., in the use of silicone rubber pellets) it must have an L/D ratio of 12 to 18.
a) Extruder The extruder should be well thermally regulated to ambient temperature. Its design should allow for easy changes of nozzles and filter screens and its head (and nozzle) should be coolable. For cable extrusions and multilayer extrusions (such as in fabric reinforced hoses) the extruders are equipped with so-called cross heads. Ideally any silicone extruder should include an option for this set up. The drive of the extruder should allow for a wide range of rpm. Torque, pressure and temperature readings have proven to be useful.
62
b) Curing tunnel Most typically the curing furnace or tunnel is horizontal. It is equipped with a conveyor belt for the transport of the extruded profile. If it is essential to produce profiles without any belt marks, one has to use a shock oven (approximately 50 cm long, up to 850 °C) that quickly cures the outer skin of the profile in front of the furnace. Figure 17 shows a scheme of this set-up. It is important that the furnace is long enough, with a wide range of temperatures, and good and homogeneous heat transfer and distribution. In the case of both the shock zone and the curing tunnel it is highly advisable that a minimum of irradiation heat gets to the extrusion die. This minimises scorch and allows for ideal control of material viscosity. The latter – this is obvious but important – is a function of temperature.
8.3.5 Moulding HTV (General) Most typically mouldable HTV silicone rubbers are processed by press curing, transfer or injection moulding. The typical curing temp is between 170-200 °C.
Silicone Elastomers
Figure 17 Extrusion line for HTV
In order to facilitate demoulding, the mould surfaces need treatment. In many cases it is sufficient to use a detergent or an internal release agent as an additive to the formulation of the silicone rubber. In more sophisticated moulds special surface structures lead to desired moulding results. C1 and C6 typically are the peroxides used in moulding applications. For addition curing moulded parts one has to apply the respective addition curing moulding grade, and for extrusion, a special extrusion grade. In extrusion and moreover in the following section dimensional stability and mechanical strength are important even before the cure of the product.
8.3.6 Calendering HTV Some solid silicone HTV rubbers are designed for processing by calendering. During calendering silicone rubber passes through 3 or more rollers while being formed into a strip. Often calendering is used for preforming rubber strips on fabrics or just simple strips which then cure. Often it is important to use a so-called high green strength rubber which allows for sufficient mechanical stability of the uncured strips. Such high green strength
rubbers (e.g., ELASTOSIL® R 760/60-70) not only exhibit high stability of strips, they would also be good material for extrusion. Thus a high green strength usually means good extrudability. One of the measures for high green strength are the viscosity parameters Williams plasticity and Mooney viscosity. However, as in calendering the high green strength behaviour is more a result of elongation flow (strips are pulled), there is no direct parameter that would fully describe high green strength behaviour. Table 55 gives a comparison of standard silicone rubbers versus high green strength silicone rubbers and their preferred use. Fabrics need pre-treatment with primers before coating with silicone rubber strips in order to provide good adhesion between rubber and fabric. Different primers are required for different elastomers and substrates. The fabrics can be coated with solvent containing primers. The application is such that the fabric is coated with the primer by immersion, painting, spraying, etc. After drying off the solvent it is advisable to cure the primer at approximately 130 °C for say 10 minutes. The primers must be protected from moisture. As a consequence it is essential to apply them onto a dry or dried fabric.
Table 55 Comparison of high green strength (HGS) behaviour of various solid silicone rubbers HTV Material type (ELASTOSIL® R, Grade)
Mooney viscosity (Start; end value)
Williams plasticity
Application
401/70, standard
66;60
313
General purpose
402/60, HGS
59;56
278
Extrusion
402/75, HGS
81;72
302
Extrusion
760/70, HGS
71;68
400
Calendering, extrusion
63
Silicone Elastomers
Another technique is to apply a so-called adhesive base which is previously calendered onto the fabric in the required thickness. The adhesive base allows extremely high adhesion. Cohesive failure is often found in tests. It is popular to use the adhesive base in the manufacture of rollers. A more detailed description of primers is beyond the intended scope of this article (see a.11, a.12, and technical bulletins from material suppliers). One of the most prominent examples of applications for calendered goods is fabric reinforced hoses as often used in the automotive industry. Such hoses are used as coolant or turbocharger hoses (the latter are very sophisticated composites). The calendered HTV/fabric strips are wrapped in layers around preformed mandrels. The outer layer is then protected with a bandage of, e.g., polyethylene terephthalate (PET). For pressureless curing one can use crosslinker E. However, typically one uses C1 or C6 with bandages protecting the catalysed rubber from contact with oxygen. The curing takes place in steam autoclaves.
8.3.7 Rollers The components of rollers are an elastic silicone rubber layer which adheres to a solid metal or plastic core. Again, one can use a primer or a special adhesive base to provide the adhesion between solid/elastic components. Rollers are cured with crosslinkers C1 or C6, as the compression set is much lower than in the case of crosslinker E. The same bandages apply for rollers as in case of calendering. After curing in a steam autoclave the bandages are removed, and the roller surface gets its final finish by grinding.
Self adhesive silicone rubbers are demouldable (with the exception of adhesive bases) while sticking to the substrate. For rubber to metal applications the latest development is an addition cured one component solid silicone rubber. It cures rapidly and adheres well to steel and various plastics.
9 SUMMARY The versatility of silicone elastomers is enormous, which is why this review has only covered the major applications, groups of materials and the most important processing techniques. Textile coatings have been mentioned as an extra field of applications. This field and some others would again fill an article of this size. The beauty of silicone elastomers is that they show many advantages over organic rubbers, such as easy processing, much shorter processing times, and improved physical and chemical properties. Just by their appearance and pigmentability, their inert and biocompatible compositions, silicone elastomers have a great number of future applications. Because of these features silicone elastomers are being used to substitute organic rubbers. Silicone elastomers are special: there is no other material exhibiting a similar spectrum of properties because of the silicone chemistry. The behaviour is not entirely inorganic and not entirely organic. The structure of a polydimethyl siloxane is apolar and chemically quite inert. Silanes and silicones undergo chemical reactions by laws that are different to those of organic molecules. It took the industry more than 50 years of the last century to characterise this chemistry and use it in elastomers.
Composites of hard and soft materials such as the previously mentioned rollers and calendered articles often require adhesion between substrate and silicone. Silicone rubber bonding has been reviewed (a.11).
The seemingly small material family of silicone elastomers will continue to develop in variety of materials, innovative individual types and specific advantages in processing. For example, 10 years ago nobody would have expected HTV rubber to be available in pellet form, to allow fully automatic processing and with no need for secondary treatment because the curing system has such a low level of emissions.
The most spectacular developments in the recent past refer to self adhesive technology.
Who would have thought that there could be a self adhesive silicone elastomer that would stick to substrates
8.3.8 Bonding
64
Silicone Elastomers
when moulded while not sticking to the mould? The latter would not even require a release agent! One can predict many such surprises as silicone elastomers develop further. Innovations will strengthen and complement current advantages and will contribute to many different problem solutions. For example, saving energy, protecting the environment, saving human lives, and, of course, much more.
ABBREVIATIONS AND ACRONYMS BgVV
Bundesinstituts für gesundheitlichen Verbraucherschutz und Veterinärmedizin
C1
Dicumyl peroxide
C6
2,5-(bis-t-butylperoxy-)-2,5dimethylhexane
CIPG
Cured-in-place-gasket
CS
Compression set
E
2,4-dichlorodibenzoylperoxide
ECU
Electronic control unit
EPDM
Ethylene-propylene terpolymer
EtO
Ethylene oxide
FDA
US Food and Drug Administration
FIPFG
Formed-in-place-foamed-gasket
FIPG
Formed-in-place-gasket
GMP
Good manufacturing practice
GP
General purpose
HCR
High consistency rubber
HGS
High green strength
HTV
High temperature vulcanising, solid silicone rubber
BS 6853, Code of Practice for Fire Precautions in the Design and Construction of Passenger Carrying Trains, 1999.
IC
Integrated circuit
LIM
Liquid injection moulding
a.8
K. Wieczorek, High Performance Elastomers 2000, Berlin, Germany, 2000, Paper 10.
LOI
Limiting oxygen index
a.9
ASTM D624-00e1, Test Method D624-00e1 Standard Test Method for Tear Strength of Conventional and Vulcanized Rubber and Thermoplastic Elastomers, 2000.
LR
Liquid rubber
LSR
Liquid silicone rubber
MEG
Monoethylene glycol
G. Kollmann in Organosilicon Chemistry IV, Ed., N. Auner and J. Weis, Wiley-VCH Weinheim, 2000, 710.
NPC
No post cure
NR
Natural rubber
P. Jerschow and W. Strassberger in Handbook of Rubber Bonding, Ed., B. Crowther, Rapra Technology Ltd., Shawbury, UK, 2001, 287.
PA
Polyamide
PBT
Polybutylene terephthalate
PC
Post cure
PC
Polycarbonate
ADDITIONAL REFERENCES a.1
W. Noll, Chemistry and Technology of Silicones, Verlag Chemie, Weinheim, 1968.
a.2
A .Tomanek, Silicone und Technik, WackerChemie, Carl Hanser, Munich, 1990.
a.3
UL2196, Tests for Fire Resistive Cables, 2001.
a.4
UL94, Tests for Flammability of Plastics Materials for Parts in Devices and Applications, 1996.
a.5 a.6
a.7
a.10
a.11
a.12
ISO 4589, Plastics – Determination of Burning Behaviour by Oxygen Index, 1996. ASTM D 2863, Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index), 2000.
P. Jerschow, Rubber Bonding 2000, Amsterdam, The Netherlands, 2000, Paper 14.
65
Silicone Elastomers
PDMS
Polydimethyl siloxane
PET
Polyethylene terephthalate
PF
Phenol-formaldehyde resin
PMMA Polymethyl methacrylate POM
Polyacetal
PP
Polypropylene
PPE
Polyphenylene ether
PPO
Polyphenylene oxide
PPS
Polyphenylene sulfide
PU
Polyurethane
PVC
Polyvinyl chloride
RTV
Room temperature vulcanising
RTV-1
Room temperature vulcanising, one component
RTV-2
Room temperature vulcanising, two component
T&D
Transmission and distribution
t90
Time needed to reach 90% vulcanisation under isothermal conditions
TPE
Thermoplastic elastomer
UL
Underwriters Laboratory
UV
Ultraviolet
VDE
Verband Deutscher Elektrotechniker
XLR®
Extra liquid rubber
66
References and Abstracts
References from the Rapra Abstracts Database Item 1 Patent Number: EP 1106654 A2 20010613 SILICONE RUBBER COMPOSITION KEYPADS Sugimoto S; Sato T Dow Corning Toray Silicone Co.Ltd. The above composition comprises a silicone rubber base produced by mixing under heat (A) a crosslinkable diorganopolysiloxane and (B) 20 to about 250 parts by weight calcium carbonate powder per 100 parts by weight of component (A), and (C) a curing agent consisting of (i) an organic peroxide or (ii) an organohydrogenpolysiloxane and a platinum catalyst in an amount sufficient to effect cure of the composition. EUROPEAN COMMUNITY; EUROPEAN UNION; JAPAN; WESTERN EUROPE-GENERAL
Accession no.818527 Item 2 Revue Generale des Caoutchoucs et Plastiques 77, No.790, Nov.2000, p.68-9 French ENGEL: THE PLASTICS TRUMP CARD Delannoy G An account is given of developments by Engel in injection presses, including vertical and horizontal machines for rubber moulding, special machines for the processing of silicone rubbers, and machines for use in multi-material moulding. ENGEL; ENGEL FRANCE AUSTRIA; EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.818407 Item 3 Patent Number: US 6184260 B1 20010206 METHOD FOR MAKING NANOPOROUS SILICONE RESINS FROM ALKYLHYDRIDOSILOXANE RESINS Zhong B Dow Corning Corp. A method for preparing a nanoporous silicone resin which can be used to form low dielectric constant films useful for electrical insulating coatings on electronic devices comprising (A) contacting a hydridosilicon containing resin with a 1-alkene comprising about 8 to 28 carbon atoms in the presence of a platinum group metalcontaining hydrosilation catalyst effecting formation of an alkylhydridosiloxane resin where at least 5 percent of silicon atoms are substituted with at least one group comprising about 8 to 28 carbon atoms and at least 45 percent of silicon atoms are substituted with at least one hydrogen atom and (B) heating the alkylhydridosiloxane resin of step (A) at a temperature sufficient to effect curing
© Copyright 2001Rapra Technology Limited
and thermolysis of alkyl groups comprising about 8 to 28 carbon atoms from the silicon atoms thereby forming a nanoporous silicone resin. USA
Accession no.817427 Item 4 Journal of Sol-Gel Science and Technology 21, No.1/2, June 2001, p.75-81 BIOACTIVITY AND MECHANICAL PROPERTIES OF POLYDIMETHYLSILOXANE (PDMS)-CAO-SIO2 HYBRIDS WITH DIFFERENT PDMS CONTENTS Kamitakahara M; Kawashita M; Miyata N; Kokubo T; Nakamura T Kyoto,University Hybrid materials were synthesised by a sol-gel process from polydimethylsiloxane (PDMS), calcium oxide, and silicon dioxide as potential bone replacement materials. They were investigated for their surface apatite formation and release of silicon in simulated body fluid, and subjected to Fourier transform infrared spectroscopy, thin film X-ray diffraction, and three-point bending mechanical tests. The surface formation of apatite is a measure of the materials ability to bond to bone in situ. The surfaces were examined by scanning electron microscopy. The material with PDMS : tetraethoxysilane (TEOS) + PDMS weight ratio 0.3, calcium nitrate : TEOS molar ration 0.15 and water : TEOS molar ratio 2 showed high apatite-forming ability, low silicon release, and mechanical properties similar to human cancellous bone. 26 refs. JAPAN
Accession no.817314 Item 5 Patent Number: EP 1090967 A2 20010411 COMPOSITION FOR FILM FORMATION, METHOD OF FILM FORMATION, AND INSULATING FILM Kurosawa T; Hayashi E; Youngsoon S; Konno K; Shiota A; Yamada K JSR Corp. A polyorganosiloxane-based composition for film formation, which gives a film having low dielectric constant and high elastic modulus and which is useful as an interlayer insulating film in semiconductor devices, comprises (A) a product of hydrolysis and condensation obtained by hydrolysing and condensing, in the presence of an alkali catalyst, at least one compound(s) of given formulae and (B) a product of hydrolysis and condensation obtained by hydrolysing and condensing, in the presence of an acid catalyst, at least one of the above compounds. EUROPEAN COMMUNITY; EUROPEAN UNION; JAPAN; WESTERN EUROPE-GENERAL
Accession no.817003
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References and Abstracts
Item 6 Rubber and Plastics News 30, No.21, 14th May 2001, p.12 DOW SILICONE SEALANT OFFERS UV, WEATHER RESISTANCE Dow Corning’s 700 Industrial Grade Silicone Sealant has been used by an unnamed car manufacturer to re-coat a PVC-jacketed electrical cable that had faded and cracked from weathering and exposure. Rather than replace the cable, Dow Corning suggested the sealant as an alternative remedy. After testing the adhesion and UV protection of the silicone formulation, an industrial painting engineer was employed to coat 7,200 feet of cable on the automaker’s plant roof, saving the company about 400,000 US dollars. The sealant cures at ambient temperatures to a tough, rubbery solid that is virtually unaffected by UV light, ozone, rain and extreme temperatures. DOW CORNING CORP. USA
Accession no.816787 Item 7 Rubber and Plastics News 30, No.21, 14th May 2001, p.11-2 FULL OF PROMISE McNulty M Silicone rubber has been popular in the automotive and medical device industries for some time, but it is emerging as a more commonly used material in the electronics, aerospace, sealants, baby products and a wide assortment of other markets. Annual growth is estimated at around 4-5%. NuSil Technology attributes the steady improvement to several factors, including silicone’s ability to perform well under extremes. Liquid silicone is ideal for the healthcare industry because it is clean and has the ability to withstand chemical and foreign body contamination. The material has also benefited from fears of allergies related to natural rubber latex. In the electronics industry, silicone is used for coating systems, electrically and thermally conducted applications and as an insulating application. USA
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substituents may be cured by wide beam electron beam exposure. USA
Accession no.816249 Item 9 Kunststoffe Plast Europe 91, No.4, April 2001, p.32-3 SILICONE BONDS Kraibuhler H Arburg GmbH New injection moulding concepts are discussed which have been instrumental in the increase in the use of injection moulded silicone parts for technical applications. Such developments include multi-component applications, sprueless injection moulding, and economic micromoulding thanks to new micro-metering units. (Article translated from Kunststoffe 91 (2001) 4, pp.8889). EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.815269 Item 10 Patent Number: US 6169142 B1 20010102 THERMAL CONDUCTIVE SILICONE RUBBER COMPOSITIONS AND METHOD OF MAKING Nakano A; Hashimoto T Shin-Etsu Chemical Co.Ltd. Silicone rubber parts having a high thermal conductivity and low hardness are obtained by moulding and curing a composition comprising (A) 100 parts by weight of an alkenyl-bearing organopolysiloxane having a viscosity of up to about 500,000 centistokes at 25 degree C., (B) 3001, 200 parts by weight of aluminium oxide powder, (C) 0.05-10 parts by weight of an alkoxysilane of the formula: R1a Si(OR2)(4-a) wherein R1 is a monovalent 6-20 C hydrocarbon group, R2 is a C.sub.1-6 alkyl group, and a=1, 2 or 3, (D) a platinum group metal catalyst, and (E) an organohydrogenpolysiloxane containing at least two SiH groups in a molecule. The composition is formulated so as to suppress the viscosity increase of a liquid silicone rubber composition due to heavy loading of aluminium oxide. JAPAN; USA
Item 8 Patent Number: US 6177143 B1 20010123 ELECTRON BEAM TREATMENT OF SILOXANE RESINS Treadwell C; Yang J; Ross M Disclosed are electron beam cured siloxane dielectric films, which are useful in the production of integrated circuits. A siloxane polymer having less than 40 mole percent carbon containing substituents or at least approximately 40 mole percent carbon containing
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Accession no.815127 Item 11 Rubber and Plastics News 2 22, No.13, 9th April 2001, p.3 WACKER-CHEMIE ADDS TO LIQUID SILICONES Begin S Wacker-Chemie has expanded its line of cost-saving, selfadhesive liquid silicone rubbers. Last year the company
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References and Abstracts
finalised development of nine additional grades of Elastosil LR for the automotive industry. The grades differ according to their resistance to temperature, oil and coolant. Elastosil LR is said to be ideal for overmoulding thermoplastics and metal parts, in applications ranging from exhaust pipe hangers and engine mounts to multifunctional steering wheel switches, air regulator membranes and automotive cables. Elastosil LR grades incorporate an adhesion agent which slowly diffuses out of the rubber and then sticks between it and the plastic or metal during two-component injection moulding. Metal and plastic substrates can remain unprimed, saving cost and time. WACKER-CHEMIE GMBH EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.814724 Item 12 Patent Number: US 6159398 A1 20001212 METHOD OF MAKING REPLICAS WHILE PRESERVING MASTER Savant G D; Hosseini A Physical Optics Corp. An improved method of making laminated optical components using a master and several submasters is disclosed. A glass/photoresist master is made by recording optical surface features in the photoresist with coherent or incoherent light. The master is processed to reveal the surface features. A frame is fastened to the edges of the photoresist/glass master with edges rising slightly above the top surface of the master. Silicone rubber is poured into the frame over the photoresist layer and allowed to cure. The silicone rubber submaster is then separated from the photoresist/glass master. Use of silicone rubber permits separation of the submaster without damaging the master. Additionally, silicone rubber is less prone to shrinkage than prior art submasters, thus permitting more accurate copying of the surface features of the photoresist/ glass master. Subsequent epoxy replicas may then be made from the silicone rubber submaster. USA
Accession no.813549 Item 13 Rubber and Plastics News 30, No.16, 5th March 2001, p.16-7 PLUG-LESS SILICONE GASKETS OFFER NEW WAY TO FIRE ENGINE Begin S The advantages of a new gasket, called the Multiple Spark Ignition Gasket, developed by Gasket King, are highlighted. The gasket consists of a pre-ceramic silicone rubber with fabric reinforcements and a wire ignition system embedded in the middle of the gasket. Location of a multiple spark in the gasket creates “surround
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combustion”, an optimal method of burning fuel in an engine’s combustion chamber. The gasket may be retrofitted on current engines without major changes to the engine and is expected to greatly minimise emissions and increase fuel efficiency. GASKET KING USA
Accession no.813046 Item 14 Materie Plastiche ed Elastomeri 65, Nos.7/8, July/Aug.2000, p.560/9 Italian PLASTICS THAT DENTISTS LIKE Baucia G Applications of plastics, filled composites and silicone rubbers in dentistry are examined with reference to materials and product developments by a number of companies. Dentists’ chairs and associated equipment produced by Italian companies and incorporating plastics, composite and PU foam components are also described. EUROPEAN COMMUNITY; EUROPEAN UNION; ITALY; WESTERN EUROPE; WORLD
Accession no.812725 Item 15 International Polymer Science and Technology 28, No.2, 2001, p.T/6-8 OIL BLEEDING BEHAVIOUR OF SELFLUBRICATING LIQUID SILICONE RUBBERS Pohmer K Wacker-Chemie GmbH The diffusion of silicone oil from self-lubricating liquid silicone rubbers is examined. Methylphenyl silicone oils, added to self-lubricating liquid silicone rubbers distribute homogeneously in rubber and are incompatible with silicone rubber. This incompatibility is the result of the differences in the chemical potential between the two phases of the system. Factors affecting the diffusion or bleeding of oil from the rubber are examined, with reference to applications such as automotive weather seals. 5 refs. (Translated from Gummi Fasern Kunststoffe, No.10, 2000, p.709) EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.811250 Item 16 Patent Number: US 6156241 A1 20001205 IOLS AND PRODUCTION METHODS FOR SAME Tran D Q; Lind R J Allergan Intraocular lenses (IOLs) are produced using a combination of steps, which increase the pull strength
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References and Abstracts
between the fixation member of the IOL and the optic of the IOL without requiring sophisticated high frequency corona discharge activation, plasma activation or other exotic activation of the fixation member or primer coating of the fixation member. The silicone polymeric optic members can be formed, for example, moulded, without recesses to accommodate the fixation members. Such recesses can be formed and provided with a quantity of silicone polymeric material precursor composition after the optic members are produced. The fixation members are then placed in the recesses and secured to the optic members. USA
Accession no.809891 Item 17 Patent Number: EP 1079398 A2 20010228 SILICONE RUBBER COMPOSITIONS, THEIR PREPARATION AND USE IN HIGH-VOLTAGE ELECTRICAL INSULATION CONTEXTS Meguriya N; Azechi S; Sekiguchi S Shin-Etsu Chemical Co.Ltd. Disclosed is a thixotropic silicone rubber composition comprising (A) an organopolysiloxane having, on average, at least two alkenyl groups in a molecule and a degree of polymerisation of up to 1,200, (B) a liquid organohydrogenpolysiloxane having at least two hydrogen atoms each attached to a silicon atom, (C) aluminium hydroxide, (D) an addition reaction catalyst, (E) a thixotropic agent and, optionally, (F) a tackifier. It cures at room or elevated temperature into a silicone rubber having high strength and electrical insulating properties sufficient to serve as a high-voltage electrical insulator. The composition is so thixotropic that it may be used to repair chipped portions of insulators. EUROPEAN COMMUNITY; EUROPEAN UNION; JAPAN; WESTERN EUROPE-GENERAL
Accession no.808483 Item 18 Macromolecular Materials and Engineering Vols.284-5, Dec.2000, p.76-80 RUBBER PROCESSING WITH GAS-ASSISTED INJECTION MOULDING (R-GAIM) Haberstroh E; Wehr H IKV Gas-assisted injection moulding was used to produce hollow parts made of rubber (EPDM) and liquid silicon rubber (LSR). The technique could be applied more easily to LSR moulding than to the processing of EPDM compounds used in this study. The gas needle and gas injection area needed to be adapted to the processing characteristics of the rubber in injection moulding. Further studies will include the determination of the basic requirements for mould design, the refinement of the process control, different gas-assisted injection moulding
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variants, limitations of the process and necessary material characteristics. 14 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.807879 Item 19 Composites Science & Technology 61, No.3, 2001, p.453-8 STUDY OF THE FEASIBILITY OF A MONOBLOCK RACING MOTORCYCLE RIM Legrand M; Ngoc Q A P ENSAM Details are given of the use of silicone rubber tools for manufacturing the monoblock of a racing motorcycle. The tool is made by vulcanising and inflating uncured sheets of silicone rubber inside a forming mould. During cooling these tools are regulated under a controlled pressure in order to obtain an optimal pressing. 5 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.807674 Item 20 Journal of Applied Polymer Science 79, No.12, 21st March 2001, p.2251-7 CHARACTERISTICS OF SURFACE WETTABILITY AND HYDROPHOBICITY AND RECOVERY ABILITY OF EPDM RUBBER AND SILICONE RUBBER FOR POLYMER INSULATORS Jin Kuk Kim; In-Hwan Kim Gyeongsang,National University Test slabs of EPDM and silicone rubber were assessed for long-term pollution resistance by subjecting the slabs to a surface corona ageing treatment. The results obtained showed good hydrophobicity of these materials and their transfer of the contaminant layer deposited on the shed surface of the insulator. The EPDM and silicone rubbers are polymers of low density and they maintain significant resistance to attack by oxygen and ozone. This study measured the contact angle between water droplets and other materials to determine the hydrophobicity and recovery ability of these synthetic polymers. Surface morphology was also studied in order to obtain a visual confirmation of the migration phenomena. 15 refs. SOUTH KOREA
Accession no.807404 Item 21 Revista de Plasticos Modernos 79, No.527, May 2000, p.582-8 Spanish NEW GAS PERMEABLE HYDROGELS FOR PROLONGED USE CONTACT LENSES
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References and Abstracts
Lasagabaster A; Moreno F; Rodriguez M A; de la Orden M U Madrid,Universidad Complutense
effects. Data are presented for polylactic acid, polyglycolic acid, lactic acid-glycolic acid copolymers and silicone polymers. 39 refs.
Problems of corneal damage caused by the prolonged wear of contact lenses are discussed, and developments in highly oxygen permeable polymeric hydrogels aimed at overcoming such problems are examined. Consideration is given to the oxygen permeability, mechanical properties, wettability and resistance to lipid deposition of hydrogels based on a number of polymers, with particular reference to silicone polymers commercially used in the manufacture of contact lenses. 15 refs.
USA
EUROPEAN COMMUNITY; EUROPEAN UNION; SPAIN; WESTERN EUROPE
Accession no.807118 Item 22 Analytical Chemistry 73, No.1, 1st Jan.2001, p.8-12 MICROMOSAIC IMMUNOASSAYS Bernard A; Michel B; Delamarche E IBM Research Division Miniaturised mosaic immunoassays were developed based on patterning lines of antigens onto a surface (polydimethylsiloxane) by means of a microfluidic network. Solutions to be analysed were delivered by the channels of a second microfluidic network across the pattern of antigens. Specific binding of the target antibodies with their immobilised antigens on the surface resulted in a mosaic of binding events that could readily be visualised in one screening using fluorescence. It was thus possible to screen solutions for antibodies in a combinatorial manner with great economy of reagents and at a high degree of miniaturisation. Such mosaic-format immunoassays were compatible with the sensitivity and reliability required for immunodiagnostic methods. 27 refs. SWITZERLAND; WESTERN EUROPE
Accession no.805159 Item 23 Journal of Biomedical Materials Research 55, No.1, April 2001, p.33-9 IN VITRO BIOCOMPATIBILITY ASSESSMENT OF NATURALLY DERIVED AND SYNTHETIC BIOMATERIALS USING NORMAL HUMAN UROTHELIAL CELLS Pariente J-L; Kim B-S; Atala A Boston,Harvard Medical School A primary normal human urothelial cell culture was used to evaluate the in vitro biocompatibility of natural and polymeric biomaterials. The cell viability, metabolic activity, apoptotic properties and DNA-synthesis activity were measured to determine cytotoxicity and bioactive
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Accession no.804585 Item 24 Journal of Materials Science. Materials in Medicine 12, No.1, Jan.2001, p.15-21 DESIGN OF A SIMULATED URETHRA MODEL FOR THE QUANTITATIVE ASSESSMENT OF URINARY CATHETER LUBRICITY Jones D S; Garvin C P; Gorman S P Belfast,Queen’s University Details are given of the development of an in vitro urethral model to characterise and compare the insertion and removal properties of commercially available intermittent catheters. The tensile properties of the silicone catheters was also evaluated. 16 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.804576 Item 25 Plastiques & Elastomeres Magazine 52, No.6, Aug./Sept.2000, p.14/7 French TEXTILE COATING Desne F Rhodia Silicones The use of silicone rubbers in the coating of fabrics for clothing and automotive air bags is discussed, and reference is made to developments by Rhodia Silicones in Rhodorsil and Silbione silicone rubbers for use in such applications. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.803934 Item 26 Plastiques & Elastomeres Magazine 52, No.6, Aug./Sept.2000, p.8-11 French SURVEY OF SILICONE ELASTOMERS Gouin F Consideration is given to the vulcanisation, processing, properties and applications of silicone rubbers, and reference is made to some developments by Dow Corning, Rhodia and Wacker in silicone rubbers and platinum curing agents. RHODIA SILICONES; WACKER SILICONES; GESSIL; DOW CORNING CORP. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; GERMANY; USA; WESTERN EUROPE
Accession no.803932
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Item 27 Adhasion Kleben & Dichten 42, No.4, 1998, p.40 German SEALING DEVICES FOR PLUG-IN CONNECTIONS Under the brand name GelTek the firm Raychem from Ottobrunn has brought out seals that are suitable for sealing plug-in connections in motor vehicles, especially for the new generation of miniaturised, high-pole plug-in connections with a narrow contact gap. These seals are based on a molecularly cross-linked silicon gel jointing compound. This article also looks at wire contacts and production of cable trees. Additional sealants are not required. With slight pressure the gel seals joints immediately making them watertight. RAYCHEM EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.803787 Item 28 Journal of Applied Medical Polymers 4, No.2, Autumn 2000, p.81-7 MECHANICAL CHARACTERISATION OF SILICONE ELASTOMER FOR USE IN A MEDICAL DEVICE Sarnowski E Sulzer Carbomedics Inc. A report is presented on the development of a set of constitutive models to account for softening in silicone rubbers for heart valve prostheses. These models were distributed throughout a finite element mesh and used in the design of a heart valve. A comparison was made of the maximum predicted stress with data obtained from in load-controlled fatigue testing in order to predict the service life of the designs and a fatigue specimen designed, analysed and tested to provide fatigue-lifetime data. 10 refs. USA
Accession no.803436 Item 29 Antec 2000.Conference proceedings. Orlando, Fl., 7th-11th May, 2000, paper 534 CATHETER DESIGNED TO GIVE IMMEDIATE, PAINLESS, OUT-PATIENT RELIEF TO BPH SUFFERERS Czuba L Herbst LaZar Bell Inc. (SPE) The development of a silicone rubber catheter for the treatment of benign prostatic hyperplasia is described. The catheter is used to introduce a microwave antenna into the affected area, and consists of multi-walled tubing to
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provide cooling, and has a compression balloon with a fixed outside diameter to create a biological stent in the affected area. 3 refs. USA
Accession no.803381 Item 30 Antec 2000.Conference proceedings. Orlando, Fl., 7th-11th May, 2000, paper 532 POLYURETHANE AND SILICONE AS NONALLERGENIC ALTERNATIVES TO LATEX FOR MEDICAL BALLOONS Shah T M Polyzen Inc. (SPE) Polyurethanes and polysilicones have been developed for medical applications which match the mechanical and physical properties of natural latex, and are not allergenic. They also have enhanced chemical resistance and reduced UV sensitivity. Products may be shaped by dip moulding, using a heated mandrel, the polymers being dissolved in suitable solvents. These polymers are particularly suitable for the production of low pressure medical balloons. Accession no.803379 Item 31 Journal of Biomedical Materials Research (Applied Biomaterials) 53, No.6, 2000, p.646-50 TEXTURED POLYDIMETHYLSILOXANE ELASTOMERS IN THE HUMAN LARYNX: SAFETY AND EFFICIENCY OF USE Sittel C; Thumfart W F; Pototschnig C; Wittekindt C; Eckel H E Koln,Universitat; Innsbruck,Universitat The systematic application and long-term results of vulcanised polydimethylsiloxane (PDMS) particles in the treatment of glottic insufficiency in the human larynx is reported. Of ten patients treated with PDMS in the early 1990s, seven patients can be retrieved for reevaluation. Laryngeal function is assessed by videostroboscopy, expert rating and further characterised by the objective parameters of voice profile and maximum phonation time. All patients are asked for their personal impression of the results. Mean follow-up time is 88.4 months. Glottic closure is complete in five of seven patients. There are no signs of granuloma formation or other pathologic changes of the injected vocal folds. In four cases, voices are rated normal or near-normal; two voices rated as fair; one usable. All the patients report significant and lasting voice improvement. None of the patients report any problems related to PDMS. PDMS particles provide permanent augmentation of human vocal fold volume without complications. Their use is a valuable and safe alternative when a definitive one-step procedure seems advantageous. However, further studies are needed to
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References and Abstracts
assess voice improvement in comparison to other materials. 34 refs. AUSTRIA; EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.802623 Item 32 Iranian Polymer Journal 9, No.3, July 2000, p.163-7 APPLICATION OF POLYDIMETHYLSILOXANE AS ADSORBENT FOR DETECTION OF ALIPHATIC HYDROCARBON COMPOUNDS VAPOURS USING QUARTZ CRYSTAL MICROBALANCE (QCM) Mirmohseni A; Hassanzadeh V Tabriz,University Polydimethylsiloxane (PDMS) is used as adsorbent for detection and determination of some aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane and cyclohexane. The contamination of environment by these volatile organic compounds is a serious problem due to their potential human toxicity. Therefore, analysis of these compounds has become more and more important and various techniques have been developed to target this aim. A thin layer of PDMS is coated at the surface of an AT-cut gold-coated quartz crystal electrodes and a sensor based on the technique of quartz crystal microbalance is developed for the detection of these organic vapours. Detection is based on the measurement of the frequency shifts due to the adsorption of the organic compounds on the polymer film. Calibration graphs are constructed by plotting the frequency changes (delta F/Hz) against the concentration of organic compounds. Using this method, the detection of these organic vapours is successfully carried out at parts per million concentrations. 22 refs. IRAN
Accession no.802521 Item 33 Patent Number: US 6011105 A 20000104 FLAME RETARDANT SILICON RUBBER COMPOSITION FOR COATING ELECTRICAL WIRE AND CABLE Ota K; Hirai K Dow Corning Toray Silicone Co.Ltd. The above composition comprises: (a) polyorganosiloxane with a given average compositional formula, (b) microparticulate silica having a mean primary particle diameter of at least 18 nm and a specific surface area no greater than 95 sq.m./g, (c) platinum or a platinum compound, (d) triazole compound, and (e) methylsubstituted benzoyl peroxide. JAPAN
Accession no.800949
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Item 34 Patent Number: US 6111221 A1 20000829 HEAT FIXING ROLLS Miyakoshi M; Shudo S; Tomizawa N; Kondou T Shin-Etsu Chemical Co.Ltd. These include a silicone rubber layer on a cylindrical metal mandrel having a penetration of at least 10, according to ASTM D1403, and a fluoropolymer layer thereon. The silicone rubber layer is obtained by moulding and curing an addition reaction type liquid silicone rubber composition to the mandrel. The roller provides a sufficient nip width under low pressure, improved abrasion resistance, long-lasting toner release, and a satisfactory fixing function even at a high speed over a long period of time. JAPAN; USA
Accession no.800308 Item 35 European Rubber Journal 183, No.1, Jan.2001, p.18-9 JAMAK TAKES ON TRICO IN WIPER-BLADE CONTEST Begin S Premium-priced wiper blades produced by Jamak Fabrication and Trico Products will go head-to-head in the US automotive aftermarket. Jamak is touting its singleedge silicone blade it began producing in January for Texaco. The company claims the Havoline blades last two to three times as long as traditional, organic rubber blades thanks to their resistance to ozone, UV rays and extreme heat and cold. Trico insists its Teflon Blade gives superior wiper performance. Trico’s blade has a beige strip on the wiping edge to indicate the presence of Teflon that is coextruded with NR. JAMAK FABRICATION INC.; TRICO PRODUCTS CORP. USA
Accession no.799078 Item 36 Polymers for Advanced Technologies 11, Nos.8-12, Aug./Dec.2000, p.460-7 POLYSILANE LIGHT-EMITTING DIODES Suzuki H; Hoshino S; Furukawa K; Ebata K; ChienHua Yuan; Bleyl I NTT Basic Research Laboratories The development of polysilane light-emitting diodes (LEDs) made from a diaryl polysilane, poly(bis(p-nbutylphenyl)silane)(PBPS), is described and comparison is made with LEDs prepared using a conventional polysilane, polymethylphenylsilane. In contrast to LEDs based on conventional polysilanes in which a weak UV electroluminescence(EL) was detected either with a strong broad visible EL or only at low temps., room temp. pure
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near-UV EL was observed with a quantum efficiency of 0.1% photons/electron with an electron injecting Al electrode in PBPS-LEDs. The spectroscopic, electronic and structural properties of PBPS were examined and the improvements observed in the EL characteristics were ascribed to them. The possible future direction of polysilane LED research is considered and other potential optoelectronic applications of polysilanes to the active medium of lasers are mentioned. 33 refs. (5th International Symposium on Polymers for Advanced Technologies, Tokyo, Aug./Sept.1999) JAPAN
Accession no.798024
SYNTHESIS OF NITRIC OXIDE RELEASING SILICONE RUBBERS FOR BIOMEDICAL APPLICATIONS Zhang H; Schoenfisch M H; Meyerhoff M E Michigan,University (ACS,Div.of Polymer Chemistry) Two approaches for preparing nitric oxide (NO) releasing silicone rubber films are reported. Silicone rubber (SR) is widely used in industry, consumer and medical products for which NO release may prove useful. It is shown that diazeniumdiolates can be anchored onto either a polysiloxane matrix or fumed silica filler to fabricate NO releasing silicone rubbers. 14 refs. USA
Item 37 Patent Number: US 6103819 A1 20000815 ADDITIVE FOR THE PREVENTION OF NITROSAMINE FORMATION IN SILICONE ARTICLES Lewis L N; Jeram E M General Electric Co. The present invention relates to a method for making nitrosamine-free silicone articles by treating the mixture of vinyl containing organopolysiloxane and filler with hindered phenols, a nitrosamine-free composition and a nitrosamine-free article made therefrom. A preferred nitrosamine-free moulded article is a baby bottle nipple. USA
Accession no.797938 Item 38 Patent Number: US 6103804 A1 20000815 PROCESS FOR THE SEALING COMPONENTS EXPOSED TO AGGRESSIVE FUNCTIONAL FLUIDS AND RTV SILICONE COMPOSITIONS SUITABLE FOR USE THEREIN Davis T D Wacker Silicones Corp. RTV-1 silicone sealants resistant to deterioration in the presence of aggressive functional fluids are prepared from an organopolysiloxane component comprising a major amount of silanol-functional organopolysiloxane, a primary or secondary amine-functional crosslinker, and both iron oxide and magnesium oxide, optionally together with auxiliary fillers, adhesion promoters, catalysts, and customary additives. The gasket materials are particularly useful in axle and transaxle seals exposed to fuel efficiency-promoting aggressive lubricants. USA
Accession no.797924 Item 39 Polymer Preprints. Volume 40. Number 2. August 1999. Conference proceedings. New Orleans, La., August 1999, p.799-800
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Accession no.797268 Item 40 Chemical Marketing Reporter 258, No.24, 11th Dec.2000, p.FR24 SILICONE PRODUCERS ROLL OUT INVESTMENTS Boswell C There are eight major producers of silicones, with Dow Corning the largest with a 36% share of the global market, by value, in 1998. Between 1995 and 1998, the global market for silicones and silanes grew at an average annual rate of 6% from 5.7bn to 6.7bn US dollars. The greatest growth will be in Asia, where global producers are making major investments in preparation. The most recent is a joint venture announced by GE Silicones and Shin-Etsu in October which will build a facility for the production of silane monomers and siloxane intermediates at a site in Southeast Asia. The US market for silicones and silanes is valued at 2.065bn US dollars based on 1998 estimates. WORLD
Accession no.797180 Item 41 Patent Number: US 6106954 A1 20000822 SILICONE RUBBER COMPOSITIONS FOR HIGH-VOLTAGE ELECTRICAL INSULATORS AND POLYMERIC BUSHINGS Meguriya N; Azechi S; Sekiguchi S; Yoshida T Shin-Etsu Chemical Co.Ltd. A silicone rubber composition is obtained by blending (A) 100 parts by weight of an organopolysiloxane composition of the addition reaction curing type with (B) about 30 to 400 parts by weight of aluminium hydroxide, which has been surface treated with an organosilane or organosilazane substantially free of an aliphatic unsaturated group or a partial hydrolysate thereof so that the aluminium hydroxide has 0.01 to 2% by weight of carbon affixed thereto. The composition maintains silicone rubber properties even though it is loaded with large amounts of aluminium hydroxide. It cures into a
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References and Abstracts
silicone rubber having improved high-voltage electrical insulating properties and thus is suited for use as highvoltage electrical insulators. JAPAN; USA
Accession no.796589 Item 42 Silicones in Coatings II. Conference proceedings. Florida, USA, 24th-26th March 1998, paper 35 NEW GENERATION OF SILICONE ELASTOMERS FOR AIRBAG COATINGS Bohin F; Pouchelon A; Surprenant R Rhodia Silicones (Paint Research Association) When airbag technology appeared on an industrial scale in the middle of the 1980s, the first bags were neoprene coated. Although neoprene met initially the performance requirements of airbags, its efficiency was questionable in the long term. By the end of the 1980s a new trend appeared: silicone-coated fabrics. In the early 1990s, specific liquid silicone rubber (RTV-2) was developed for airbag applications. Being self-bonding onto the fibre, they require the use of solvent during the coating process. In 1996, a new generation of silicone elastomers for coating was launched onto the European market. Specifically designed to meet the airbag market evolution, these new products provide specific rheological properties allowing very thin coating without any change of the technology or any use of a solvent. This of course allows significant cost reductions for the customer. Offering improved thermal protection to the fabric, they are very well adapted to the new generation of airbag inflators arising from the market. Their specific properties also provides a 100% increase of the fabric tear strength. 6 refs. USA
Accession no.795798 Item 43 Silicones in Coatings II. Conference proceedings. Florida, USA, 24th-26th March 1998, paper 31 BIOPROTECTING ORGANOSILICONE COATINGS Voronkov M; Chernov N Irkutsk,Institute; Russian Academy of Sciences (Paint Research Association) To protect materials and parts against contamination various polymer coatings are used, containing fungicides, bactericides or other agents. Protective coatings are known, based on organosilicone polymers modified with heteroorganic compounds with antimicrobial activity, particularly organotin compounds of the R3SnX type. Heteroorganic fungicides may also be introduced into hydrolysates of Si(OC2H5)4 or Ti(OC2H5)4, which are used for clarification of optical glasses. Despite resistance to bioovergrowth, physicochemical, mechanical and
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protective properties of coatings containing heteroorganic and inorganic fungicides degrade during operation. With time they completely lose their fungicidal activity under the action of adverse climatic factors or more or less corrosive environment. This refers also to a great majority of the known fungicidal and bactericidal coatings on organic binders. Biocidal coatings based on polydiorganosiloxanes with terminal triorganostannyloxy groups were patented. However these coatings are short-lived; they are not chemically bound to the surface, and the OSnR3 terminal fragments are hydrolytically unstable. Extensive and systematic studies are performed on carbofunctional organosilicone monomers and resultant coatings. 73 refs. RUSSIA
Accession no.795794 Item 44 Silicones in Coatings II. Conference proceedings. Florida, USA, 24th-26th March 1998, paper 17 MATRIX ASSISTED PULSED LASER EVAPORATION (MAPLE): APPLICATIONS WITH FUNCTIONALISED POLYSILOXANE MATERIALS McGill R A; Chrisey D B; Mlsna T E; Pique A US,Naval Research Laboratory (Paint Research Association) A novel polymer processing technique, matrix-assisted pulsed laser evaporation (MAPLE), for the deposition of polysiloxane and other materials, as ultra-thin and uniform coatings has been developed. The technique involves directing a pulsed excimer laser beam onto a frozen matrix target composed of the polymer material in a solvent. The process gently lifts polymeric material into the gas phase with no apparent decomposition. A plume of material is developed normal to the target, and a substrate positioned incident to this plume is coated with the polymer. The MAPLE technique offers a number of features that are difficult to achieve with other polymer coating techniques, including nanometer to micron thickness range, sub monolayer thickness precision, high uniformity, applicability to photosensitive materials and patterning of surfaces. Highly functionalised polysiloxanes are synthesised and deposited on a range of substrates by the MAPLE technique, and characterised by IR spectroscopy and optical microscopy. High quality, uniform and adherent polysiloxane coatings are produced by the optimised MAPLE technique. The physicochemical properties of the coating are unaffected by the process, and precise thickness control of the coating is straightforward. 26 refs. USA
Accession no.795781 Item 45 Patent Number: EP 1043363 A2 20001011 MOTHER MOLD-FORMING SILICONE
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References and Abstracts
RUBBER COMPOSITION AND MOTHER MOLD OBTAINABLE THEREFROM Miyoshi K; Tanaka K Shin-Etsu Chemical Co.Ltd. In a silicone rubber composition comprising an organopolysiloxane as a base polymer, 0.1 to 50 parts by weight of a modified silicone fluid having a melting point of up to 100C and a refractive index difference of 0.01 to 0.05 from the base polymer is blended per 100 parts by weight of the composition. The composition is cast and cured to form a mother mould, which maintains parting properties over a long term. EUROPEAN COMMUNITY; EUROPEAN UNION; JAPAN; WESTERN EUROPE-GENERAL
Accession no.795412 Item 46 158th. ACS Rubber Division Meeting - Fall 2000. Conference preprints. Cincinnati, Oh., 17th.-19th. Oct. 2000, paper 116 PEROXIDE CROSSLINKING OF SILICONE COMPOUNDS Niijhof L B G M; Cubera M Akzo Nobel Polymer Chemicals BV; Akzo Nobel polymer Chemicals LLS (ACS,Rubber Div.) A review is presented of the crosslinking of silicone compounds by organic peroxides, with particular emphasis on the different peroxide classes available and their cure characteristics in various silicone formulations. Processing guidelines are included and the influence of certain compounding ingredients is addressed. A comparison is also made between platinum catalysed cure systems and peroxide cure systems. 9 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; NETHERLANDS; USA; WESTERN EUROPE
Accession no.794212 Item 47 Antec 2000.Conference proceedings. Orlando, Fl., 7th-11th May, 2000, paper 90 SIMULATION OF THE FILLING AND CURING PHASE IN INJECTION MOLDING OF LIQUID SILICONE RUBBER (LSR) Haberstroh E; Michaeli W; Henze E Aachen,Institut fur Kunststoffverarbeitung; GE Bayer Silicones GmbH & Co.KG (SPE) A model was developed for the filling and curing phases in the injection moulding of two-part liquid silicone rubbers, from considerations of the specific volume, the cavity pressure and the material temperature. The filling phase was modelled using 2-1/2-D simulation software based on finite element methods, in which over 90% of the cavity was filled under volume flow controlled
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conditions and the balance by the thermal expansion of the material. Curing, which is thickness-dependent, is assumed to be complete when an average degree of curing of 95% over the wall thickness is achieved, with a minimum degree of 75%. 10 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.793821 Item 48 High Performance Elastomers 2000. Conference proceedings. Berlin, Germany, 10th-11th Oct.2000, paper 13 ELASTOMERIC SILICONE ADHESIVES FOR AUTOMOTIVE ENGINE GASKETS AND SEALING Loubet O Rhodia Silicones (Rapra Technology Ltd.; European Rubber Journal) With an average growth of more than 10% each year, silicone elastomers are used more and more in the automotive industry, especially for gasketing applications requiring thermal and chemical resistance. Today, Rhodia Silicones with a wide range of gasketing technologies, i.e. silk-screened gasket, injected gasket, formed-in-placegasket (FIPG) and cured-in-place-gasket (CIPG), has reached a leading position in the automotive sealing industry. The high level of performance of silicone elastomers is achieved with an additional ease of processability of the liquid silicone, thus making it the economical solution for bonding and sealing automotive parts. Building on the company’s experience of over 30 years in automotive gasketing, the company achieves the innovation needs of customers through heat curing elastomers (HCR), RTV1 and RTV2 technologies. A new generation of elastomeric silicone adhesives targeted for plastic parts has been developed. 21 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.792375 Item 49 High Performance Elastomers 2000. Conference proceedings. Berlin, Germany, 10th-11th Oct.2000, paper 12 LIQUID SILICONE RUBBER. THE UNIQUE HIGH PERFORMANCE MATERIAL IN APPLICATIONS AND PROCESSING Trumm C Dow Corning GmbH (Rapra Technology Ltd.; European Rubber Journal) Injection moulding of liquid silicone rubbers is becoming increasingly important. One reason for this is the increased performance requirements of the finished articles. In addition, more and more producers of rubber parts are seeing benefits in the high level of automation and
© Copyright 2001 Rapra Technology Limited
References and Abstracts
productivity. Silastic liquid silicone rubber was pioneered by Dow Corning and introduced to the rubber fabrication marketplace in the late 1970s. Today the processing and product advantages of LSR are exploited in many existing and new applications. A broad product line is available both for general applications and certain LSRs tailored for specific requirements. LSRs are liquids with viscosities that vary from easily pourable to pastes. These two component materials are mostly used in a 1:1 ratio and consist of polysiloxane polymers or copolymers that are vulcanised above 120 deg.C by polyaddition. Aspects covered include technology advantages, application examples, LSR rheology, injection moulding of LSR, and properties and mould design. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.792374 Item 50 International Polymer Science and Technology 27, No.9, 2000, p.T/24-5 HEAT RESISTANCE OF SILICONE RUBBER FILLED WITH HEAT-EXPANDED GRAPHITE Dedov A V; Nazarov V G Tekhindustriya-M Closed Joint Stock Co. The influence is investigated of dispersed heat-expanded graphite on the temperature dependences of the strength of composites based on silicone rubber. It was established that heating of the material increases the mobility of the segments of the macromolecules and the relaxation rate, which leads to a more uniform distribution of the mechanical load and to an increase in the strength of the composite. Treatment of the composite at 200 degrees C for 2 hours was found to be the optimum, and the highest strength with such treatment was found to be that of a composite containing 20 wt.% heat-expanded graphite. 4 refs. Translation of Kauchuk i Rezina, No.2, 2000, p.8. RUSSIA
Accession no.791813 Item 51 Plastics, Rubber and Composites 29, No.5, 2000, p.229-34 EFFECT OF CAVITY PRESSURE ON CROSSLINK DENSITY OF INJECTION MOULDED SILICONE RUBBER Barbaroux M; Regnier G; Verdu J Dow Corning Healthcare Industries; Ecole Nationale Superieure d’Arts et Metiers The effects of injection moulding conditions (temperatures 120 and 160 deg.C, pressures from 5 to 50 MPa) on the crosslink density of the resulting parts (determined from equilibrium solvent swelling experiments) are studied for an elastomer of the liquid silicone rubber type, in which crosslinking results from platinum catalysed vinyl-silane addition. It is shown,
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unexpectedly, that a pressure increase leads to an increase in the cure rate, despite the unfavourable effect of pressure on viscosity. 22 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.789932 Item 52 Patent Number: EP 1031596 A1 20000830 KEY PAD WITH RIGID RESIN KEY TOP Nishi K Polymatech Co.Ltd. A key pad having a rigid key top is disclosed, which is not subject to key top detachment or dislocation and does not require key detachment prevention means, such as a collar. The key top is adhered to a silicone rubber key pad with a silicone base adhesive by providing a urethane base adhesion substrate layer on the back of the key top. EUROPEAN COMMUNITY; EUROPEAN UNION; WESTERN EUROPE-GENERAL
Accession no.787625 Item 53 Patent Number: US 5830951 A 19981103 POLYVINYLSILOXANE IMPRESSION MATERIAL Fiedler J H Dentsply DeTrey GmbH Improved two component polymerisable polyorganosiloxane compositions are described, particularly for use in making dental impressions, having improved tear strength and wettability. Improved tear strength results from inclusion of a quadri-functional polysiloxane having a vinyl content of 0.16 to 0.24 m-mole/g. Working time is maintained by including sufficient amounts of a retarder composition that delays onset of the vinyl polymerisation. Wettability is improved by including a surfactant resulting in a surface contact angle with water at three minutes of less than 50 degrees. The surfactant chosen has an HLB of 8-11, such that the wetting contact angle is achieved within less than two minutes and remains wetting throughout the working time of the impression taking, substantially improving impression quality. A low viscosity impression material is provided and includes a base component and a catalyst component. Both components are siloxane-based materials. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.787417 Item 54 IRC 2000. Conference proceedings. Helsinki, Finland, 13th-15th June 2000, paper 79 SILICONE RUBBER: INNOVATIONS THAT COMPETE
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References and Abstracts
Dietl S Wacker Chemie GmbH (Nordic Council of Rubber Technology) The developments in silicone rubber described open up possibilities of higher productivity and improved quality. The concept of fast peroxide-free curing/no post cure and self-bonding silicone rubber materials provide new and versatile solutions to the silicone rubber and plastic processors. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.787111 Item 55 Patent Number: US 6051642 A1 20000418 SILICONE COMPOSITION WITH IMPROVED HIGH TEMPERATURE TOLERANCE Tkaczyk J E; Klug F J; Amarasekera J; Sumpter C A General Electric Co. A high temperature insulating composite composition comprising at least one ground silicate mineral and at least one silicone polymer. The at least one ground silicate mineral is at least one mineral selected from the group of olivine group; garnet group; aluminosilicates; ring silicates; chain silicates; and sheet silicates. The high temperature insulating material has particular usefulness for insulating electrical wires.
PROSTHESIS FOR GLAUCOMA THERAPY Jafary M R; Mirzadeh H; Eslami Y; Amini H Amirkabir,University of Technology; Tehran University of Medical Science The manufacture of moulds by electroforming and preparation of prostheses with both the plate and connecting tube made from silicone rubber are described. The results of in vitro tests performed to evaluate the biocompatibility of the prostheses are also reported. 18 refs. IRAN
Accession no.786386 Item 58 Patent Number: US 6054518 A1 20000425 SILICONE RUBBER MOLDING COMPOSITIONS AND METHOD FOR PRODUCING SILICONE RUBBER MOLDED PARTS Hayashida O Shin-Etsu Chemical Co.Ltd. In a silicone rubber composition comprising an organopolysiloxane, reinforcing silica, and a curing agent, an ester wax, typically having a melting point of 40 to 150C is blended as an abherent. When the composition is moulded in a mould, the flow of the composition in the mould and the parting of the cured silicone rubber from the mould are significantly improved.
USA
JAPAN; USA
Accession no.786716
Accession no.786311
Item 56 Journal of Applied Polymer Science 78, No.4, 24th October, 2000, p.724-31 SILICON-BASED MATERIALS PREPARED BY IPN FORMATION AND THEIR PROPERTIES Tsumura M; Iwahara T Kaneka Corp.
Item 59 Patent Number: US 6069186 A1 20000530 RADIATION-CURABLE SILICONE RUBBER COMPOSITION Okinoshima H; Kashiwagi T; Yamaguchi S Shin-Etsu Chemical Co.Ltd.
Silicon-based interpenetrating networks (IPNs) were prepared from a ladder silsesquioxane oligomer and a polycarbosilane by hydrosilylation polymerisation of bifunctional Si-H and Si-vinyl monomers. This was followed by melt and compression moulding of the Bstaged resin. Materials of various shapes were formed and the flexural modulus and Izod impact strength were evaluated, and found to be larger than those for each component. The thermal, electrical and optical properties were also measured. 18 refs. JAPAN
Accession no.786476 Item 57 Iranian Journal of Polymer Science & Technology 13, No.1, Spring 2000, p.1-7 Persian PRODUCTION OF A POLYMERIC OCULAR
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A radiation-curable silicone rubber composition is provided which includes: (A) a specific organopolysiloxane having radiation-sensitive (meth)acryloyl groups at the both terminals of the molecular chain, (B) a photosensitiser; (C) a tetraalkoxysilane or a partial hydrolysis-condensation product thereof; and (D) optionally together with a specific organic titanium compound. This composition is curable upon irradiation by ultraviolet rays for a short time and exhibits adhesion quickly. Hence, it is useful for the bonding, coating and potting of various substrates. This composition also has a relatively weak adhesion immediately after curing, and can be peeled from the substrate with ease for a while. Hence, it is also suited for uses where repair is required. Because of a high curing rate, it can be effective for, e.g. making a process short, improving productivity and saving energy in the manufacture of electric and electronic parts. JAPAN; USA
Accession no.786163
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References and Abstracts
Item 60 European Rubber Journal 182, No.9, Sept.2000, p.28/31 SILICONE GRADES FOR CO-MOULDING Shaw D Wacker-Chemie has developed a new grade of liquid silicone elastomer, Elastosil LR. The benefit of this material is that it offers easy mould release after a short period of elevated temperatures, such as the cure cycle, but then goes on to develop good bond strengths over a period of 24 hours or so. This makes it ideal for overmoulding processes or where a thin layer of silicone needs to be applied over another substrate. The material bonds to thermoplastics, although not all. Applications include water-resistant mobile phones, shower heads and electrical connectors. The company is introducing a high temperature vulcanisation grade of the self-adhesive silicone later this year which has been developed for adhesion to metals. One potential application is for exhaust pipe mounts used in cars. WACKER-CHEMIE GMBH EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.785116 Item 61 Journal of Biomedical Materials Research 51, No.3, 5th Sept. 2000, p.408-12 IN VITRO FORMATION OF OROPHARYNGEAL BIOFILMS ON SILICONE RUBBER TREATED WITH A PALLADIUM/TIN SALT MIXTURE Dijk F; Westerhof M; Busscher H J; van Luyn M J A; van der Mei H C Groningen,University Silicone rubber voice prostheses were treated with a colloidal palladium/tin solution to form a thin metal coat intended to discourage biofilm formation. The effect of the coating on airflow resistance and cytotoxicity was examined. 28 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; NETHERLANDS; WESTERN EUROPE
Accession no.782970 Item 62 Patent Number: US 6042766 A1 20000328 METHOD OF FORMING ARTIFICIAL ROCK SHEATHING Bahr G J Apparatus and method for the fabrication of semi-flexible artificial rock sheathing are disclosed. A one-coat silicone elastomer is brushed or sprayed on the surface of a substantially flat natural rock formation to form a mould that is adhered to a wood-framed fibreglass cradle that holds the shape of the mould. When removed from the rock formation, the mould is sprayed with a thermoplastic elastomer to form a semi-flexible rock sheathing having
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the same characteristics as the natural rock surface from which the mould was formed. After the materials are fully cured, the sheathing sheet may be separated from the mould and used for the fabrication of rock or rock structures by attaching sheathing sheets to the exterior of a framework, followed by cutting and forming different shapes. USA
Accession no.782380 Item 63 Patent Number: US 6037279 A1 20000314 COATED TEXTILE FABRICS Brookman L; Lawson D W Dow Corning Ltd. Disclosed is a coated textile fabric, which is useful for fabricating automobile airbags. A surface of the textile fabric is coated with first and second layers of polyorganosiloxane-based elastomeric material, the first layer being disposed between the textile surface and the second layer. The polyorganosiloxane-based material of the first layer exhibits an elongation at break of at least 400%. The polyorganosiloxane-based material of the second layer exhibits a tear strength of at least 30 kN/m. USA
Accession no.780295 Item 64 Rubber World 222, No.3, June 2000, p.36/48 MULTI-COMPONENT INJECTION-MOULDING OF RIGID-FLEXIBLE COMBINATIONS Ronnewinkel C; Haberstroh E Institut fur Kunststoffverarbeitung Multi-component injection moulding offers ecological and economical advantages. Combinations of rigid and flexible materials are of major interest to the industry. Due to their properties, curing rubbers and liquid silicone rubbers allow extended applications of rigid-flexible combinations and can substitute rubber-metal parts. The examinations show a good adhesion strength between thermoplastics and LSR, and between polyamide 6,12 and X-NBR rubber. In order to find suitable mould concepts for these material combinations, it will be demonstrated how to use computer simulation for the analysis of temperature distribution and curing rate. 12 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.780117 Item 65 Rubber World 222, No.3, June 2000, p.26/35 NEW TRENDS IN SILICONE ELASTOMER TECHNOLOGY
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References and Abstracts
Burkus F S; Amarasekera J General Electric Co.,Silicones Div. Siloxanes offer unique properties as elastomers and therefore are being used in increasing amounts for such applications. Liquid injection moulded silicone materials have excellent physical and chemical properties which make them suitable alternatives to standard millable and pourable siloxane elastomers. New advances in liquid injection moulded siloxane materials, including selfbonding, low compression set and controlled force deflection, address some previous issues that have limited the use of these systems in certain applications. Advances in mould design have enabled a two-shot ETP/ liquid injection moulded elastomer system to be developed. 6 refs. USA
Accession no.780116 Item 66 Rubber and Plastics News 29, No.22, 29th May 2000, p.22 MCGHAN MEDICAL GETS OK FOR SALINE IMPLANTS Moore M McGhan Medical, a breast implant manufacturer, having received government approval to keep saline-filled implants on the market, will seek to get the near-ban on silicone-gel implants lifted. A study on silicone implants from the FDA shows that silicone implants often rupture in women’s bodies without their knowing, but McGhan says its implants are much stronger and better than the devices studied in the report. MCGHAN MEDICAL CORP. USA
Accession no.780110 Item 67 International Polymer Science and Technology 27, No.5, 2000, p.T/6-T/13. (Translation of Gummi Fasern Kunststoffe, No. 3, 2000, p. 162) PRODUCTION OF LARGE-DIMENSIONED ARTICLES FROM SILICONE ELASTOMERS Krell V The production of large-dimensioned articles from high temperature vulcanising silicone rubber and liquid silicone rubbers is described, with respect to the processing equipment, moulding tools, and processing techniques. Examples are included of products produced by these techniques, and include an outdoor terminal plug with and without field control element, long rod insulators, a lightening conductor, and an angled plug.
Item 68 International Polymer Science and Technology 27, No.4, 2000, p.T/25-T/28. (Translation of Kauchuk i Rezina, No.6, 1999, p.8) PRODUCTS MADE FROM POLYSILOXANES WITH A PROPERTY GRADIENT Britove V P; Yurkhanov V B; Nikolaev O O; Bogdanov VV St.Petersburg,State Technical University It is demonstrated that it is possible to produce products with different properties on their working surfaces, by a combination of thermal and radiation vulcanisation methods. In particular, the crosslinking of polysiloxanes for use in medical applications, is discussed. The results of modification by these combined vulcanisation techniques are examined with reference to physicomechanical properties. 8 refs. RUSSIA
Accession no.779702 Item 69 Advanced Composites Letters 9, No.2, 2000, p.115-23 ANALYSIS OF EXPLANTED SILICONE/SILICA COMPOSITE BREAST IMPLANTS Brandon H J; Young V L; Jerina K L; Wolf C J Washington,University The effect of implantation time on the physical, mechanical and chemical properties of silicone rubber (Silastic II)/silica gel breast implants was investigated and the results compared with those for lot-matched control (unimplanted) samples. In vivo duration times ranged from 4 months to 10 years. The tensile strengths of explant and control samples were determined using identical testing protocols as were the tensile strengths of implants extracted with hexane to remove non-crosslinked silicones. Average molec.wts. between crosslinks were determined by swelling measurements. 5 refs. USA
Accession no.778727 Item 70 Applied Organometallic Chemistry 14, No.6, June 2000, p.287-303 ORGANOSILICON ION-EXCHANGE AND COMPLEXING ADSORBENTS Voronkov M G; Vlasova N N; Pozhidaev Y N Russian Academy of Sciences
EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY;
Literature data concerning research organosilicon ionexchangers and complexing agents are summarised and systematised. Data on organophilic organosilicon adsorbents and sorption systems for chromatography are not considered. 136 refs.
WESTERN EUROPE
RUSSIA
Accession no.779949
Accession no.778015
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References and Abstracts
Item 71 Journal of Biomedical Materials Research (Applied Biomaterials) 53, No.3, 2000, p.267-75 FABRICATION OF MICROTEXTURED MEMBRANES FOR CARDIAC MYOCYTE ATTACHMENT AND ORIENTATION Deutsch J; Motlagh D; Russell B; Desai T A Illinois,University Details are given of the preparation of microtextured silicone membranes using photolithography and microfabrication techniques. The attachment of cardiac myocytes onto these membranes was investigated. 34 refs. USA
Accession no.777781 Item 72 Patent Number: EP 1006165 A2 20000607 COATING MATERIAL Morita Y; Furukawa H; Aso T Dow Corning Toray Silicone Co.Ltd. A highly weather-resistant coating, which exhibits excellent water resistance and water repellency, contains a vinyl-type polymer having a pendant carbosiloxane dendrimer structure. The coating is used on construction materials, buildings and structures undercoated with an organic coating material, automobiles, railroad rolling stock, ships, aircraft, bridges, commercial and industrial plants and electrical and electronic instruments and devices. EUROPEAN COMMUNITY; EUROPEAN UNION; JAPAN; WESTERN EUROPE-GENERAL
Accession no.777717 Item 73 Patent Number: EP 1006164 A2 20000607 SILICONE RUBBER BASE COMPOUND FOR ELECTRICAL WIRE COATING, SILICONE COMPOSITION FOR ELECTRICAL WIRE COATING, AND PROCESS FOR THE PRODUCTION OF SILICONE RUBBER COATED ELECTRICAL WIRE Baba K; Ota K Dow Corning Toray Silicone Co.Ltd. Disclosed is a silicone rubber base compound for electrical wire coating such that when it is extruded using an extruding machine having a variable screw with an L/D=10 and a die with a diameter of 1 mm attached thereto at a barrel and head temperature of 70C, the per-minute extruder output rate at a screw rotation speed of 100 rpm is not less than 1.2 times the extruder output rate at a screw rotation speed of 50 rpm. It may be obtained by compounding diacyl organic peroxide consisting of carbon atoms, hydrogen atoms and oxygen atoms with the silicone rubber base compound for electrical wire coating.
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EUROPEAN COMMUNITY; EUROPEAN UNION; JAPAN; WESTERN EUROPE-GENERAL
Accession no.777716 Item 74 Patent Number: US 6030684 A1 20000229 PROTECTING ELECTRONIC COMPONENTS IN ACIDIC AND BASIC ENVIRONMENT Polak A J; Baker T L Motorola Inc. Electronic devices, which are protected by an organic polymeric encapsulant and placed in a corrosive environment, can have added protection by dispersing in the encapsulant particles of a solid buffer which tend to neutralise the effect of the corrosive agent. This approach is quite effective when strong acids are the corrosive agents and when solid acid-base buffers are dispersed in the polymeric material. The encapsulant may be elastomeric. Silicone elastomers containing solid acidbase buffers are quite effective in protecting the underlying electronic device from corrosion by strong acids. USA
Accession no.777524 Item 75 Patent Number: US 5982041 A 19991109 SILICONE DIE ATTACH ADHESIVE, METHOD FOR THE FABRICATION OF SEMICONDUCTOR DEVICES, AND SEMICONDUCTOR DEVICES Mitani O; Nakayoshi K; Tazawa R; Mine K Dow Corning Toray Silicone Co.Ltd. A silicone die attach adhesive is disclosed which comprises a silicone composition which cures both through the free radical reaction of acrylic-functional organopolysiloxane as induced by exposure to highenergy radiation and through the hydrosilylation reaction between alkenyl-functional organopolysiloxane and silicon-bonded hydrogen-functional organopolysiloxane. Also disclosed is a fabrication method characterised by mounting a semiconductor chip on a substrate or in a package with the aforesaid silicone die attach adhesive sandwiched between the semiconductor chip and substrate or package, then inducing the free radical reaction of the acrylic functional groups by exposing the die attach adhesive to high energy radiation, and thereafter curing the die attach adhesive by the hydrosilylation reaction. A semiconductor device, characterised in that it has been fabricated by the above-described method, is disclosed. JAPAN
Accession no.774597 Item 76 Patent Number: US 5973061 A 19991026
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References and Abstracts
AQUEOUS SILICONE DISPERSIONS CROSSLINKABLE INTO ELASTOMERIC STATE BY DEHYDRATION Feder M; Ulrich J Rhone-Poulenc Chimie
Item 79 British Plastics and Rubber April 2000, p.23-4 LIQUID SILICONE OFFERS THE PLASTIC MOULDER A PERFORMANCE ELASTOMER
The above dispersions comprise: (a) 100 pbw of an oilin-water emulsion of an alpha-omega-(dihydroxy) polydiorganosiloxane stabilised with at least one anionic or nonionic surface active agent, or mixture thereof, (b) 1-100 pbw of an hydroxylated silicone resin containing, per molecule, at least two different recurring structural units selected from a given group, the resin having a hydroxyl group weight content of 0.1-10%, (c) 0-250 pbw of a nonsiliceous inorganic filler, and (d) 0.01-3 pbw of a metal curing catalyst compound. These dispersions have a solids content of at least 40%.
The injection moulding of liquid silicone rubber is discussed, with particular reference to the use of specially modified injection moulding machines. The characteristics and properties of silicone rubbers are described, and advantages of these properties in applications in end use industries such as automotive, electronic, medical, and household appliances. One area of application driving the growth in their use is the increase in multi-component moulding with which a sealing element can be added to a rigid component in one moulding operation. Machine design modifications are examined.
EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
WESTERN EUROPE
Accession no.774410
Accession no.771105
Item 77 European Rubber Journal 182, No.1, Jan.2000, p.21-4 TOUGH SERVICE CONDITIONS MEAN TOUGH ELASTOMERS White L
Item 80 Biomaterials 21, No.7, 2000, p.649-65 BIOMATERIALS USED IN THE POSTERIOR SEGMENT OF THE EYE Colthurst M J; Williams R L; Hiscott P S; Grierson I Liverpool,University
Fluoroelastomer growth in the US of around 4%/year in automotive uses is predicted in a recent market report. Dyneon’s base-resistant Fluorel BRE fluoroelastomers are formulated to withstand the demanding conditions found in basic and amine-containing environments, most notably those involving new lubricating fluids in the automotive industry. DuPont Dow Elastomers’ range, Viton Extreme ETP, is described as suitable for severe sealing applications requiring a combination of heat, fluids and base resistance with low-temperature flexibility. Makers of silicone elastomers and HNBR have grades which are suitable for various fuel-contact applications. USA
Accession no.772741 Item 78 International Polymer Science and Technology 26, No.5, 1999, p.44-56 HEAT CURING SILICONE RUBBERS Nagy J; Roth G The article reviews the development of silicones from silane monomers, polysiloxanes, silicone polymers and rubbers to the chemistry of crosslinking and its economic importance. Mechanical and electrical properties of a number of Wacker Elastosil silicone rubbers are compared. Applications of silicone rubbers are also listed. 14 refs. Abs. translation from Muanyag es Gumi, No.2, 1999, p.45. EASTERN EUROPE; HUNGARY
Accession no.771233
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This review focuses on disorders affecting retinal detachment, and briefly describes the eye anatomy and the nature and treatment of posterior segment eye disorders. The roles, required properties and suitability of materials used in vitreoretinal surgery such as scleral buckles, tamponade agents or drug delivery devices are reviewed. Materials used in posterior segment eye surgery range from non-degradable solid implants to water-soluble fluids. Silicone oil is currently the most suitable vitreous tamponade for long-term use but has many disadvantages. Silicone in solid and non-biodegradable form has been used for scleral buckles (explants attached to the outside of the eye by sutures). Water-swellable hydrogel material can be used for buckling procedures. Vitreous substitute materials used in eye repair include semifluorinated alkanes, silicone-fluorosilicone copolymer oil, methylated collagen, hydroxypropylmethyl cellulose, and crosslinked polyvinyl alcohol. 132 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.769343 Item 81 Patent Number: EP 992560 A1 20000412 PROCESS FOR SEALING COMPONENTS EXPOSED TO AGGRESSIVE FUNCTIONAL FLUIDS AND RTV SILICONE COMPOSITIONS SUITABLE FOR USE THEREIN Davis T D
© Copyright 2001 Rapra Technology Limited
References and Abstracts
Wacker-Chemie GmbH RTV-1 silicone sealants resistant to deterioration in the presence of aggressive functional fluids are prepared from an organopolysiloxane component comprising a major amount of silanol-functional organopolysiloxane, a primary or secondary amine-functional crosslinker, and both iron oxide and magnesium oxide, optionally together with auxiliary fillers, adhesion promoters, catalysts, and customary additives. The gasket materials are particularly useful in axle and trans-axle seals exposed to fuel efficiency-promoting aggressive lubricants. EUROPEAN COMMUNITY; EUROPEAN UNION; USA; WESTERN EUROPE-GENERAL
Accession no.769052 Item 82 Patent Number: US 6004496 A 19991221 METHOD OF MAKING A SILICONE RUBBER WINDSHIELD WIPER Reo N J Specialty Silicone Products Inc. High performance silicone rubber windshield wiper blades are provided as a result of moulding a tintable platinum group metal catalysed silicone compositions having an intrinsic viscosity of less than 1.3. Improved lubricity with respect to windshield wiper glass is achieved by a moulding procedure which effects a transfer such as a migration, or diffusion of release agent, for example polytetrafluoroethylene, into the surface of the silicone rubber windshield wiper blade. USA
Accession no.768871 Item 83 Injection Molding 8, No.4, April 2000, p.42/4 USING TECHNOLOGY TO STAY ON TIME AND UNDER BUDGET Maniscalco M Boston Medical Products uses a combination of rapid prototyping, rapid tooling and 3D CAD to bring lowvolume, injection moulded silicone rubber medical devices to market on time and at a competitive price. Rapid prototypes of the actual mould insert are produced on a Sanders system. A toolmaker works with these prototypes and returns sintered tool inserts within two weeks. BOSTON MEDICAL PRODUCTS INC.; CADKEY INC.; NDM INC. USA
Accession no.768540 Item 84 Patent Number: US 6001943 A 19991214
© Copyright 2001Rapra Technology Limited
SILICONE GEL COMPOSITION AND SILICONE GEL FOR USE IN SEALING AND FILLING OF ELECTRICAL AND ELECTRONIC PARTS Enami H; Hamada Y; Nakamura A; Saiki T Dow Corning Toray Silicone Co.Ltd. The present invention provides a silicone gel composition for use in sealing and filling of electrical and electronic parts, which are characterised by the fact that when the composition is cured, the composition forms a silicone gel in which the loss elastic modulus at a temperature of 25 deg C, and a shear frequency of 0.1 Hz is 100 to 1000 Pa, and in which the complex elastic modulus is 100000 Pa or less, and a silicone gel which is characterised by the fact that in a silicone gel which seals or fills electrical or electronic parts, the loss elastic modulus of this silicone gel at 25 deg C and a shear frequency of 0.1 Hz is 100 to 10000 Pa, and the complex elastic modulus is 100000 Pa or less. JAPAN
Accession no.766438 Item 85 Patent Number: EP 982345 A1 20000301 CONTINUOUS PROCESS FOR PRODUCING A SILICONE POLYMER Currie J; Griffith P; Herron W; Taylor R Dow Corning Corp. This involves the sequential steps of (i) polymerisation of a linear silanol group containing siloxane by condensation polymerisation or of a cyclosiloxane by ring opening polymerisation or of a mixture of the linear and cyclosiloxanes with a phosphazene base in the presence of water and the presence or absence of a filler in an extruder, (ii) neutralising the reaction mixture in an extruder and (iii) stripping the neutralised reaction mixture to remove volatile materials. Preferably, step (iii) is performed in an extruder. More preferably, steps (i), (ii) and (iii) are all performed in the same extruder. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE; WESTERN EUROPE-GENERAL
Accession no.766190 Item 86 New Scientist 165, No.2223, 29th Jan.1999, p.36-9 BORDER OF ORDER Brooks M The secret of the winter flounder’s survival is a tiny antifreeze protein: as the disordered water molecules in its blood begin to turn into the ordered structure of ice, the protein moves in to break them apart. Just as the flounder can hold molecular order at bay in its bloodstream, researchers are learning to map and control the boundaries between ordered and disordered materials. Eventually, they hope this will help them devise better
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ways to preserve frozen foods or design materials with remarkable properties to order. But first the researchers aim to marry the processing power of silicon with the flexibility of plastics to create cheap, bendy and disposable electronics. If researchers can make the marriage work, it could lead to drug packaging that sports unbreakable polymer display screens, for example. Touch the screen and health information or medical advice could be at your fingertips. There would be countless uses for computer screens that could be worn on a sleeve or rolled up and stuffed in a pocket - an electronic map for tourists, for example, or a complete set of wiring diagrams for an engineer working at a remote location. This plastic-silicon combination could also be used to make speakers, microphones or a new generation of sensors to spot pollutants or diagnose disease. Details are given. CORNELL UNIVERSITY USA
Accession no.765153 Item 87 Biomaterials 21, No.6, 2000, p.629-36 MICROGROOVED SILICONE SUBCUTANEOUS IMPLANTS IN GUINEA PIGS Walboomers X F; Jansen J A Nijmegen,University Cell-substratum interactions are of fundamental importance for the reaction of body tissues to surgically implanted foreign materials. The influence of 2 mu m wide microgrooves, with various depths (0.5-6 mu), on capsule formation around subcutaneous silicone implants, is investigated in an animal experiment. Silicone sheets with microtexture are glued around silicone tubes. These implants are placed subcutaneously in eight guinea pigs for ten weeks. The implanted tubes are removed including all surrounding tissues, and processed for light microscopy and subsequent histomorphometrical evaluation. All removed implants are surrounded by a thin fibrous capsule, and it is observed that this capsule is separated from the implants by a thin, single layer of mono- and multinucleated phagocytotic cells. In histomorphometry no significant differences are seen in relation to the reaction towards the various textures. It is concluded that microtextures do not have an effect on the morphological characteristics of capsule formation around silicone implants in soft tissue. 32 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; NETHERLANDS; WESTERN EUROPE
Accession no.765055 Item 88 Patent Number: US 5985945 A 19991116 FOAMABLE SILOXANE COMPOSITIONS AND SILICONE FOAMS PREPARED THEREFROM Loiselle B P; Rapson L J
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Dow Corning Corp. Foamable organosiloxane compositions are disclosed which yield, upon cure, silicone foams having low density and decreased friability, comprising a siloxane base polymer having an average of at least two hydroxyl groups per molecule, a silicon-containing crosslinker for the siloxane base polymer, wherein the crosslinker contains at least two -SiH groups per molecule; a platinum group catalyst; a silicone resin copolymer; and, optionally, a blowing agent; and silicone foams prepared therefrom. A method of weather-stripping a door or window using a silicone foam so prepared is also disclosed. USA
Accession no.764891 Item 89 Kunststoffe Plast Europe 90, No.2, Feb.2000, p.32-3 SILICONE COMPOSITES Pohmer K The development of innovative self-adhesive liquid silicones has made it possible, for the first time, to produce rigid/flexible composites in thermoplastics and silicones using hardened steel moulds without any coating. WACKER-CHEMIE GMBH EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.764600 Item 90 Pitture e Vernici 76, No.2, 1st-15th Feb.2000, p.31-6 Italian; English WATER-BASED SILICONE SEALANTS. EVOLUTION OR REVOLUTION Giraud M Y; Feder M; Dubouis R Conchem Various aspects of the water-based silicone sealants industry are discussed in some detail. Information presented includes a brief historical review, a brief comparison of conventional sealants, market research carried out by Rhone Poulenc, preparation of sealants by the emulsion polymerisation and by Rhodalis technology and a comparison of the two methods, and a comparison with other sealants. RHONE-POULENC SA EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.763094 Item 91 Medical Device & Diagnostic Industry Nov.1999, p.38/44 SILICONE RUBBER FOR MEDICAL DEVICE APPLICATIONS
© Copyright 2001 Rapra Technology Limited
References and Abstracts
Heide C Vesta Inc. A general overview is presented of silicone rubbers, including information on physical properties, fabrication methods and potential advantages for medical device manufacturing. Their chemical structure and curing mechanisms are also investigated. 4 refs. USA
Accession no.760269 Item 92 156th ACS Rubber Division Meeting - Fall 1999. Conference preprints. Orlando, Fl., 21st-23rd Sept.1999, paper 93 SILICA-PDMS INTERACTIONS - A NEW VIEW OF AN OLD QUESTION Barthel H Wacker-Chemie GmbH (ACS,Rubber Div.) Fumed silica is an amorphous synthetic silicon dioxide used in a variety of technical applications. Besides free flow of powders and thickening of liquids, the reinforcement of silicone elastomers is of main importance. Mechanisms of reinforcement are still an issue of scientific discussions. However, it has been settled that interactions between the silica surface and the polydimethylsiloxane (PDMS)chain segments play a major role. Recent efforts to understand those interactions, both on a molecular and an atom scale level, are reviewed. Hydroxylated and silylated silicas with defined degree of silylation are investigated. As an experimental adsorption technique, inverse gas chromatography, in an infinite dilution and a finite concentration mode, is used. Adsorption of linear oligomers of dimethylsiloxy units reveal that steric factors dominate the energy of adsorption. On an atom-scale level, a series of computational studies together with experimental vibration spectroscopy is performed. Semi-empirical quantum chemical techniques, basing on AM1 and PM3 parameters, are used to study nanoscale surface facets. Unspecific, dispersion forces together with induced dipole-dipole interactions control the adsorption of PDMS- on fumed silica, and discrete H-bonding are of minor importance. A review on various results of structures and interaction energies from different methods is presented. 35 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.759686 Item 93 156th ACS Rubber Division Meeting - Fall 1999. Conference preprints. Orlando, Fl., 21st-23rd Sept.1999, paper 73 REVIEW OF MECHANICAL VERSUS MANUAL NICKING OF SILICONE RUBBER
© Copyright 2001Rapra Technology Limited
Briggs G; Korthals K Laur Silicone Rubber Compounding Inc. (ACS,Rubber Div.) A mechanical nicking device is initially evaluated to see if there is justification, through testing, for its purchase. The goal is to achieve more accuracy and precision in the Tear Die B tests (ASTM D 624). The original test uses silicone samples of different durometers and three operators. In this phase, it is shown that the standard deviation varies less when done by mechanical means. Research is continued using side by side comparisons on various materials with actual production lots. A database is created tracking Tear Die B standard deviation for the mechanical versus hand nicking. The performance of each method is reviewed using silicone materials with a range of durometers. 4 refs. USA
Accession no.759667 Item 94 156th ACS Rubber Division Meeting - Fall 1999. Conference preprints. Orlando, Fl., 21st-23rd Sept.1999, paper 72 SILICONE FOAM - CAN IT MEASURE UP Suprenant R; Wolosen M; Larson E; George C Rhodia Silicones Inc. (ACS,Rubber Div.) Silicone foam materials have been available commercially for many years. The materials have been either heat cured rubber or RTV (room temperature vulcanised). Emphasis is placed on RTV preparation of foam, details are given of the tools needed to develop low density, high strength properties. The development of analytical tools used in efforts to produce silicone foam suited to compete with PU foam are examined. 158 refs. USA
Accession no.759666 Item 95 156th ACS Rubber Division Meeting - Fall 1999. Conference preprints. Orlando, Fl., 21st-23rd Sept.1999, paper 69 COMPRESSION SET BEHAVIOUR OF ADDITION CURABLE SILICONE RUBBER Meguriya N; Yoshida T Shin-Etsu Chemical Co.Ltd. (ACS,Rubber Div.) Injection moulding of liquid silicone rubber is becoming increasingly important. Compared to conventional compression moulding, liquid injection moulding systems (LIMS) can be moulded at a much faster pace and accuracy, required for less steps, which reduces labour cost and improves productivity. LIMS material has superior purity and clarity as well as low odour and neutral taste because it is cured through addition (hydrosilylation)
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reaction, so that no by-products are produced and the whole process goes in closed system. They can also be produced fully automatically (no runners, flashless, autoejection) if the system is designed properly. Silicone rubber is used in many fields for their various properties not available in any other organic rubbers. Compression set of silicone rubber is very low and varies little -50 deg.C to 200 deg.C, compared to organic rubbers which are not suitable for use as sealing materials at their extreme temperature. JAPAN
Accession no.759663 Item 96 Philadelphia, PA, 1998, pp.18. NALOAN. MIL-I-46852. INSULATION TAPE, ELECTRICAL, SELF ADHERING UNSUPPORTED SILICONE RUBBER US Military MIL-I-46852 Version C Notice 1. Superseded by A-A-59163 on 13/2/ 98. Photocopies and loans of this document are not available from Rapra. USA
Accession no.759594 Item 97 156th ACS Rubber Division Meeting - Fall 1999. Conference preprints. Orlando, Fl., 21st-23rd Sept.1999, paper 68 NEW TRENDS IN SILICONE ELASTOMER TECHNOLOGY Burkus F S; Amarasekera J General Electric Silicones (ACS,Rubber Div.) The trend to high performance, long lasting industrial subsystems is driving the need for high-performance elastomers. A high performance elastomer should maintain material integrity while being exposed to harsh environmental conditions including thermal cycling, solvent and chemical exposure, high pressures and high stress environments. Silicone elastomers are the materials of choice for such applications and have inherent benefits when compared to standard organic elastomers. These properties are described, and compared and contrasted with those of other elastomeric systems. New material developments and processing techniques have resulted in the use of silicone elastomers in applications previously unattainable. These new material developments are discussed, as is the process of liquid injection moulding of elastomers with an emphasis on product design, the structures of the siloxanes used, the productivity of the process and the properties of the resulting elastomer. 6 refs. USA
Accession no.758361
Item 98 Journal of Thermal Analysis and Calorimetry 57, No.1, 1999, p.323-8 DEVELOPMENT OF A NEW SILICONE BASE TRANSDERMAL SYSTEM. III. STUDY OF THERMAL PROPERTIES OF SILICONE ELASTOMERS CONTAINING LIQUID INGREDIENTS Wagner O; Kenessey G; Liptay G Budapest,Technical University; MOL Hungarian Oil & Gas Co. Commonly-used base silicone elastomers for transdermal therapeutic systems, i.e. cured polydimethylsiloxanes, were studied with particular reference to the change of the inner polarity of silicone elastomers containing various amounts of polar liquid ingredients and trifunctional silicone additives. It was shown that the polarity of the inside of the matrix was related to the diffusion properties of model substances and thermal properties of silicone elastomers. The ingredients used changed the matrix framework, which was also influenced by the type of trifunctional additive. These properties were markedly dependent on the timing of the measurement. Measurements carried out after 48 hours of the production of the polymer showed reproducible properties, indicating that the final structure of the polymer was formed. These results showed that the ingredients influenced the properties of the silicone matrices significantly, so that the characteristics of drug release from pharmaceutical forms could also be varied. 10 refs. EASTERN EUROPE; HUNGARY
Accession no.755874 Item 99 Adhasion Kleben & Dichten 41, No.9, 1997, p.26/32 German FOAMING OR FOAMABLE SEALS (PART I)? Kayed J Wil SG (Schweiz) Foam-in-place seals promise great savings in costs compared with pre-formed sealing elements. The market offers different methods and materials, so that the most varied problem definitions can be solved. First aid to help decide on the choice of the right system is given in this article. Part II of this contribution, published in the next edition (Oct.1997), surveys the properties of starting materials and completed seals as well as special technical processes. A list of references appears in the 1997 October issue. Technical aspects here cover foaming polyurethane mechanisms and silicones, as well as chemically foaming seals, physically foamable seals and hot melts for foamin-place seals, including temperature and air moisture as processing parameters. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; SWITZERLAND; WESTERN EUROPE
Accession no.754449
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Item 100 Rubber and Plastics News 29, No.5, 4th Oct.1999, p.6 SURGICAL METHODS IMPACTING PROCESSORS Boyd J Trends in surgical procedures have led to the increased use of minimally invasive surgical procedures in place of traditional ‘open body’ methods for operations such as gall bladder surgery, hysterectomies and appendectomies. These techniques are creating opportunities for silicone rubber processors, since silicone rubber offers advantages over other materials such as PVC, latex and polyurethanes in terms of biocompatibility and processability. Problems with latex allergies, and perceived potential hazards with PVC are leading to their replacement with silicone rubber medical equipment, including long-term implants such as pacemakers. USA
Accession no.753319 Item 101 Rubber Chemistry and Technology 72, No.1, March-April 1999, p.152-164 BASIC STUDY OF CONTINUOUS ULTRASONIC DEVULCANISATION OF UNFILLED SILICONE RUBBER Diao B; Isayev A I; Levin V Y Akron,University Prepared samples of a peroxide cured silicone rubber were devulcanised by passing through an extruder fitted with an ultrasonic die at different throughput rates and back pressures. A branched structure in the network of the devulcanised material, the degree of which depends on the amplitude of the ultrasonic waves, is indicated. Assessment of amount of devulcanisation was made with gel fraction and crosslink density measurements. The devulcanised samples were then revulcanised with further peroxide, both alone and blended with fresh silicone rubber. Mechanical properties of the revulcanised samples were compared with both the original vulcanised samples and those prepared from a blend of devulcanised and fresh material. Indications are that a blend of devulcanised and fresh material has similar tensile but higher elongation than virgin material. (Originally presented to ACS meeting, Cleveland, Oct 21-24, 1997, revised May 98) 17 refs USA
Accession no.753130 Item 102 Plastics Technology No.10, Oct.1999, p.54/61 LIQUID INJECTION MOLDING HITS ITS STRIDE Ogando J
© Copyright 2001Rapra Technology Limited
Growth in the use of liquid injection moulding as a processing method is examined, as suppliers in North America report sales growth in liquid silicone rubber in excess of 10% a year, and producers of liquid injection moulding machines also report a similar picture of double digit growth. Trends and developments driving this growth are discussed, and include the ability to mould bigger parts, the availability of higher mould cavitation, gas-assist moulding, the possibility to produce dual-durometer parts and thermoset/thermoplastic combinations. Developments in machinery are reviewed with details of specific machines. NORTH AMERICA
Accession no.752983 Item 103 European Coatings Journal No.10, 1999, p.26/42 SILICONES FOR WATERBORNE WOOD COATINGS Easton T; Cackovich A Dow Corning Europe The aim of this paper is to demonstrate the versatility of silicone technology in meeting the demands of wood coatings. The choice of a suitable additive or combination thereof, are shown to provide improved surface lubricity, gloss, levelling, blocking and chemical resistance. Details are given of new chemical structures and delivery forms of silicone which provide better performance in water based wood coatings. Physical and chemical modification techniques are discussed for polydimethyl siloxane. 4 refs. EUROPE-GENERAL
Accession no.751612 Item 104 155th ACS Rubber Division Meeting, Spring 1999. Conference Preprints. Chicago, Il., 13th-16th April 1999, Paper 83, pp.16 CLOSED LOOP FUZZY CONTROL OF PART WEIGHT IN INJECTION MOLDING OF LIQUID SILICONE RUBBER (LSR) BASED ON PVT BEHAVIOR Haberstroh E; Henze E IKV (ACS,Rubber Div.) A closed loop system based on pressure-volumetemperature behaviour for the control of part weight in the injection moulding of liquid silicone rubber is described. Depending on the course of cavity pressure and mould temperature, a fuzzy logic based algorithm determines the required changes in dosing volume in the case of process disturbances and ensures a constant part weight. 3 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; USA; WESTERN EUROPE
Accession no.749893
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Item 105 155th ACS Rubber Division Meeting, Spring 1999. Conference Preprints. Chicago, Il., 13th-16th April 1999, Paper 80, pp.18 MULTI-COMPONENT INJECTION MOLDING OF RIGID-FLEXIBLE COMBINATIONS MADE FROM THERMOPLASTICS, RUBBER AND LIQUID SILICONE RUBBER Ronnewinkel C; Haberstroh E IKV (ACS,Rubber Div.) Factors influencing adhesion between rubber and thermoplastic components in parts produced by twomaterial injection moulding are examined. Results are presented of studies undertaken to optimise adhesion in parts produced by this technique from liquid silicone rubber and polyamides or PBTP. 22 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; USA; WESTERN EUROPE
Accession no.749891 Item 106 Patent Number: US 5952403 A 19990914 MEDICAL ELECTRICAL LEAD AND REINFORCED SILICONE ELASTOMER COMPOSITIONS USED Paulsen M J; Miller J P; Ebert M J Medtronic Inc. A medical electrical lead and a reinforced silicone elastomer used therein. The silicone elastomer used is preferably made from a novel silica reinforced polysiloxane material, which after vulcanisation by crosslinking exhibits improved mechanical properties. The medical electrical lead features an electrode at a distal end thereof and an elongated electrical conductor extending between the electrode and the connector, the conductor in electrical contact with the electrode at a distal end and in electrical contact with the electrode at a distal end, the conductor comprised of several wires or wire bundles wound in a multifilar coil configuration. USA
Accession no.749726 Item 107 Patent Number: US 5952397 A 19990914 PHOTO-CURABLE LIQUID SILICONE RUBBER COMPOSITIONS FOR TEMPLATING MOTHER MOLDS Fujiki H; Sakamoto T Shin-Etsu Chemical Co.Ltd. A photo-curable liquid silicone rubber composition is curable upon exposure to light into a cured product having a Shore A hardness of 20-60 and a light transmittance of at least 10% at a wall gauge of 10 mm. The composition is suitable for forming a transparent templating mother
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mould which allows a photo-curable liquid resin cast therein to be cured with light transmitted by the mould wall. JAPAN
Accession no.749721 Item 108 Patent Number: US 5858287 A 19990112 EXTRUSION METHOD OF PRODUCING A POLYMERIC SEALING/SPRING STRIP Scott M K Crane Plastics Co.Ltd. The present invention pertains to a polymeric sealing/ spring strip and method of producing the same. The polymeric strip has various embodiments which are based upon the incorporation of silicone rubber. Some of the embodiments are based on the formation of a resilient silicone rubber surface to provide a sealing/spring contact with an opposing surface period. Other embodiments incorporate the silicone rubber in such ways as to utilise its resilient properties to produce a sealing/spring strip which has improved mechanical resilience properties. The method allows the production of a sealing/spring strip in accordance with the present invention by using extrusion techniques. USA
Accession no.746980 Item 109 Polymer Bulletin 42, No.6, July 1999, p.717-24 SOLID PARTICLE EROSION OF ELECTRICALLY INSULATING SILICONE AND EPDM RUBBER COMPOUNDS Besztercey G; Karger-Kocsis J; Szaplonczay P Furukawa Electric Institute of Technology; Institut fuer Verbundwerkstoffe GmbH; Kaiserslautern,University; Furukawa Composite Insulators A study was made of the particle jet erosion behaviour of outdoor insulating silicone and EPDM rubber compositions subjected to sandblasting. The effects of impact angle and amount of non-reinforcing filler (alumina trihydrate) and the wettability of the sandblasted, contaminated silicone rubber surfaces in the incubation period are discussed. 8 refs. EASTERN EUROPE; EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; HUNGARY; WESTERN EUROPE
Accession no.745933 Item 110 Patent Number: US 5919437 A 19990706 COSMETIC CREAM COMPOSITION CONTAINING SILICONE GEL MATERIAL Lee W; Bianchini R J; Hilliard P J Colgate-Palmolive Co.
© Copyright 2001 Rapra Technology Limited
References and Abstracts
Disclosed is a solid cosmetic composition (e.g. a cream composition) containing an active cosmetic material (e.g. a deodorant active, an antiperspirant active, a sunscreen, an insect repellent and/or an anti-fungal agent) and a silicone gel material. The silicone gel material includes (a) a volatile silicone material and (b) an organopolysiloxane material as a gelling agent, able to form a gel after being mixed with the volatile silicone material. The organopolysiloxane material can be a reaction product of a vinyl-terminated siloxane polymer and a hydride crosslinking agent. The composition can be formed by mixing the active cosmetic material and silicone gel material at ambient temperature. The compositions do not need particulate or clay thickeners or waxy gelling agents. USA
Accession no.745873 Item 111 Rubber and Plastics News 28, No.24, 28th June 1999, p.1/21 STUDY FINDS BREAST IMPLANTS DON’T CAUSE ILLNESS Moore M Silicone gel breast implants do not cause cancer or systemic disease in women, according to a governmentfunded study. But other complications, such as implant rupture and deflation or contraction of the fibrous tissue around the breast, are fairly common and need to be studied further, concluded the three-member panel organised under the auspices of the Institute of Medicine, the medical arm of the National Academy of Sciences. Dow Corning, inventor of silicone implants, said the report ‘provides additional solid evidence that breast implants do not cause disease’. The panelists, who have no connection with any parties in the silicone implant dispute and worked without compensation, reviewed more than 3,000 publications on implants, giving particular weight to peer-reviewed scientific articles. All the evidence indicates that rupture, tissue contraction and other local complications resulting in pain, disfigurement or infection are the main problems with silicone implants, according to the study. Details are given. US,NATIONAL ACADEMY OF SCIENCES; US,INSTITUTE OF MEDICINE; DOW CORNING CORP.
benzoyl peroxide having a maximum grain diameter not exceeding 50 micrometers and an average grain diameter of 30 micrometers. When cured, it exhibits reduced nonuniformity in the physical properties because of fewer voids, resulting in decreased frequency of spark-outs in insulated wires. JAPAN
Accession no.744615 Item 113 Patent Number: US 5889109 A 19990330 SILICONE RUBBERS WITH IMPROVED MOLD RELEASE PROPERTIES Knies W; Guske W Wacker-Chemie GmbH The invention relates to polyorganosiloxane rubber compositions which vulcanise to elastomers under the influence of heat and comprise: (A) 100 parts by weight of organopolysiloxane; (B) 10 to 200 parts by weight of filler; (C) 0.1 to 10 parts by weight of crosslinking agent which forms free radicals; and (D) 0.05 to 10 parts by weight of aliphatic alcohol with C8 to C30 alkyl radicals. The aliphatic alcohol (D) acts as an internal mould release agent. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.744249 Item 114 Patent Number: US 5886111 A 19990323 SILICONE SEALING MATERIAL EXHIBITING HIGH STRESS RELAXATION Chiotis A; Wojtowicz J Raychem Corp. A silicone gel formulation is described having a Voland hardness of from about 6 to 30 grams, a tack of from about 17 to 35 grams, and a stress relaxation greater than 50%. The material is especially suitable for sealing the back end of connectors containing a multiple of fine wires with gauges between about 14 gauge and 28 gauge. It is particularly suitable to seal the back end of an automotive connector subjected to a wide variety of harsh environmental conditions. USA
Accession no.741955
USA
Accession no.745570 Item 112 Patent Number: EP 939103 A2 19990901 SILICONE RUBBER COMPOSITION Baba K; Hirai K; Matsushita T Dow Corning Toray Silicone Co.Ltd.
Item 115 Patent Number: US 5911711 A 19990615 LUBRICANT SYSTEM FOR HYPODERMIC NEEDLES AND METHOD FOR ITS APPLICATION Pelkey B J Becton,Dickinson & Co.
This comprises a polyorganosiloxane gum of given formula, microparticulate silica and a methyl-substituted
A lubricious coating having a first layer formed from at least a partially cured organosiloxane copolymer and
© Copyright 2001Rapra Technology Limited
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PDMS having a viscosity greater than about 1,000 centistokes and a second layer including PDMS having a viscosity between about 50 and 350 centistokes is applied to and adherent to the outside surface of the elongate tube of the hypodermic needle. USA
Accession no.741175 Item 116 Patent Number: US 5911317 A 19990615 LIGHT PERMEABLE METAL PLATED RUBBER KEY Tsai J Silitek Corp. The key is made of silicone rubber and has a hardened head on top printed with light-permeable ink. The key is metal plated and replaces rubber keys and keys with adhered rubber and silicone rubber. TAIWAN
Accession no.741173 Item 117 Patent Number: US 5814259 A 19980929 METHOD FOR MOULDING STRUCTURAL PARTS UTILISING MODIFIED SILICONE RUBBER Weiser E S; Baucom R M; Snoha J J US,National Aeronautics & Space Administration This invention improves upon a method for moulding structural parts from preform material. Preform material to be used for the part is provided. A silicone rubber composition containing entrained air voids is prepared. The silicone rubber and preform material assembly is situated within a rigid mould cavity used to shape the preform material to the desired shape. The entire assembly is heated in a standard heating device so that the thermal expansion of the silicone rubber exerts the pressure necessary to force the preform material into contact with the mould container. The introduction of discrete air voids into the silicone rubber allows for accurately controlled pressure application on the preform material at the cure temperature. USA
Accession no.740203 Item 118 Kunststoffe Synthetics No.1, 1998, p.12-4 German NEW USES WAITING FOR DISCOVERY Pohmer K; Spirig N Bayer AG; Lonstroff AG Silicone rubbers have an average growth rate of 5%. They can be injection moulded with a special mix and dosing technology. Easily processable, they can be made into
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combinations with thermoplastics into a range of applications from babies’ dummies and the membranes in breathing masks, to long-wave stabilizers, gaskets for irons, percolators, dishwashers and washing machines. In combined materials the usual processing temperature is 180-230C but this becomes much less in combinations using liquid silicone rubber (LSR). LSR has a heat stability to 200C, cold flexibility to -50C, good mechanical properties over a long time, chemical resistance and electrical and thermal isolation. Combined with thermoplastics, LSR is also used in hair-dryer diffusers. There are 2,000 LSR parts in the average car. 4 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.739935 Item 119 Rubber World 220, No.3, June 1999, p.35-7 COINJECTION MOULDING FOR LIQUID SILICONE RUBBER Timmerman J Engel GmbH Coinjection moulding is an exciting new process for the moulding of liquid silicone rubber that opens up new possibilities. Coinjection involves injecting two or more similar materials into the mould cavity together. One material forms the skin and the other forms the core. The process is described, together with equipment requirements and design considerations. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.739157 Item 120 Muanyag es Gumi 36, No.2, Feb.1999, p.45-56 Hungarian HEAT-CURING SILICONE RUBBERS Nagy J; Roth Gy Budapest,Technical University The authors review heat-curing solid and liquid silicone rubbers, with particular regard to the properties, processing characteristics and wide applicability of this group of elastomers. 14 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. EASTERN EUROPE; HUNGARY
Accession no.738759 Item 121 Adhesive Technology 16, No.2, June 1999, p.31 UNDER PRESSURE Greene K
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References and Abstracts
Adhesive Research Inc. Adhesives play multiple roles in the construction of airbag inflators. Adhesive Research first supplied adhesives to the airbag industry when Seal Methods encountered a problem with its acrylic adhesive system which was releasing combustible gases during inflation. It was determined that silicones, with their thermal stability, low outgassing characteristics and capacity for a tight, hermetic seal, were most promising. USA
Accession no.735653 Item 122 Journal of Biomedical Materials Research (Applied Biomaterials) 48, No.3, 1999, p.354-64 SILICONE GEL BREAST IMPLANT FAILURE AND FREQUENCY OF ADDITIONAL SURGERIES: ANALYSIS OF 35 STUDIES REPORTING EXAMINATION OF MORE THAN 8,000 EXPLANTS Marotta J S; Widenhouse C W; Habal M B; Goldberg E P Florida,University; Tampa Bay,Craniofacial & Plastic Surgery Center Although it is well known that silicone gel breast implants (SGBIs) produce many local complications and necessitate frequent surgical revisions, no large cohort retrospective quantitative analysis of clinical data has been reported to date, especially for the prevalence of failures and additional surgeries. Data from 35 different studies that encompass more than 8,000 explanted SGBIs are analysed and reported. Because examination of a prosthesis when explanted is the definitive method for determining shell integrity, the only studies used are ones that report implant duration, the total number of SGBIs explanted and the number of SGBIs for which shell rupture or failure (not intact) is confirmed upon surgical removal. An exponential regression plot of data indicates a direct correlation of implant duration with percent shell failure. SGBI failure is found to be 30% at 5 years, 50% at 10 years and 70% at 17 years. The failure rate is 6%/ year during the first five years following primary implant surgery. ANOVA comparison of three implant age groups (mean implant durations of 3.9, 10.2 and 18.9 years) indicates a highly significant statistical correlation of percent failure with implant duration. Complications necessitating at least one additional surgery occur for 33% of implants within six years following primary implant surgery. Shell failure is found to be an order of magnitude greater than the 4 to 6% rupture prevalence suggested by the AMA Council on Scientific Affairs in 1993, the 0.2 to 1.1 % cited by manufacturers at that time and the 5% rupture that was stated to be ‘not a safety standard that the FDA can accept’. 71 refs. USA
Accession no.734781
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Item 123 International Rubber Exhibition and Conference 1999. Conference proceedings. Manchester, 7th-10th June 1999, Materials paper 1. BENEFITS OF SILICONE ELASTOMERS IN AUTOMOTIVE APPLICATIONS Youren J Dow Corning Ltd. (Crain Communications Ltd.) Automotive engines have become increasingly complex and powerful and the engine compartment more crowded. This has resulted in higher temperatures and more aggressive environments for rubber components. These changes have resulted in increasing use of silicone elastomers for a variety of engine seals covering fuel and oil applications, ignition components and dynamic seals. Increasing safety requirements together with miniaturisation has resulted in silicones being widely used in airbag production rather than organic rubbers. Many of the above applications are described, together with the use of existing and new product and process technologies to make today’s silicone automotive components. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.734464 Item 124 Antec ’99. Volume III. Conference proceedings. New York City, 2nd-6th May 1999, p.2934-7. 012 SELECTION OF SILICONE SEALANTS FOR HEAVY TRUCK AND OFF-ROAD VEHICLE APPLICATIONS Brennan J E; DiPaola D J Texas Instruments Inc. (SPE) The unique sealing requirements encountered in heavy truck and off-the-road vehicle applications warrant the investigation of silicone sealants for this marketplace. The candidate sealants are subjected to a selection protocol based on lap shear strength as a function of cure time and after immersion in water, engine wash fluid and common automotive fluids. An acid cure silicone does not adhere well to chromate plated steel, and its adhesion to brass deteriorates after fluid immersions. A neutral cure silicone adheres well on any of the substrates, and retains adhesion after fluid immersions. Neutral cure materials are recognised as the best choice for future product performance testing. 3 refs. USA
Accession no.734271 Item 125 Antec ’99. Volume 1. Conference proceedings. New York City, 2nd-6th May,1999, p.539-44. 012 COMBINING LIQUID-SILICONE-RUBBERS WITH THERMOPLASTICS TO RIGID-
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FLEXIBLE COMBINATIONS USING 2COMPONENT INJECTION MOULDING Ronnewinkel C; Haberstroh E Institute for Plastics Processing (SPE) The production of components consisting of flexible silicone rubber bonded to rigid thermoplastics using twocomponent injection moulding techniques is discussed. The strength of the bond at the interface between a polyamide and silicone rubber was investigated using an injection moulded tensile test bar. It was concluded that such components could replace rubber-metal combinations for certain applications. 15 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.732951 Item 126 Adhesives & Sealants Industry 6, No.3, April 1999, p.38-9 PSAS INCREASE SAFETY AND EFFECTIVENESS OF AIRBAG INFLATORS Adhesives Research and Seal Methods have jointly developed a new generation of pressure sensitive adhesivecomponent solutions for automotive airbag inflator applications. In general, adhesives for airbag inflators serve to position and set the airbag in place, hermetically seal the propellant and attach the propellant cover. It was determined that silicones, with their thermal stability, low outgassing and capacity for a tight hermetic seal, were most promising. ADHESIVES RESEARCH INC.; SEAL METHODS INC. USA
Accession no.731126 Item 127 Kauchuk i Rezina (USSR) No.6, 1998, p.10-6 Russian ELECTRICAL CONDUCTIVITY OF FLEXIBLE MATERIALS Zuev Yu S A review is presented of recent studies on the effect of various factors on the electrical conductivity and volume resistivity of polymeric systems, also covering the effect of plasticisers and fillers on the volume resistivity, and the anomalously low resistivity of black-filled fluorinecontaining rubbers and silicone rubber. Flexible materials (vulcanisates, thermoplastic elastomers, sealants and others) are classified in terms of their resistivity. 72 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. RUSSIA
Accession no.726960
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Item 128 Journal of Biomedical Materials Research 45, No.3, 5th Jun.1999, p.240-50 SHEEP, PIG, AND HUMAN PLATELETMATERIAL INTERACTIONS WITH MODEL CARDIOVASCULAR BIOMATERIALS Goodman S L Connecticut,University The haemocompatibility of pyrolytic carbon mechanical heart valve leaflets, PE, and silicone rubber was examined. Data are given for ovine, porcine and human platelets. 49 refs. USA
Accession no.726766 Item 129 China Synthetic Rubber Industry 22, No.2, Mar.1999, p.70-3 Chinese ADVANCES IN ADDITION SILICONE RUBBER Tan Bi’en; Pan Huiming; Wang Weixing; Zhang Lianzheng; Zhao Feiming South China,University of Technology; Beijing,Aerospace Institute of Materials & Processing Technology Advantages in research of addition silicone rubber in high strength, high heat resistance and addition injection moulding were reviewed. 18 refs. CHINA
Accession no.726408 Item 130 Kauchuk i Rezina (USSR) No.5, 1998, p.33-6 Russian METHOD OF CALCULATING THE FREE PLAY OF A SEAL OPERATING OVER A WIDE TEMPERATURE RANGE Shindler V M; Khalo T P A method is described for calculating the required tightness of fit of seals based on siloxane rubbers operating in widely varying temperature conditions. 6 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. RUSSIA
Accession no.723338 Item 131 Revue Generale des Caoutchoucs et Plastiques No.769, June/July 1998, p.66/73 French HIGH TEMPERATURE VULCANISING ELASTOMERS IN THE BIOMEDICAL SECTOR
© Copyright 2001 Rapra Technology Limited
References and Abstracts
Leuci C Rhodia Silicones The structure, properties and biomedical applications of high temperature vulcanising silicone rubbers are examined. The conformity of Rhodia Silicones’ Silbione silicone rubbers with European and US regulations covering such applications is discussed, and results are presented of studies of the behaviour of these elastomers when subjected to different sterilisation techniques. 6 refs. EU; EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; USA; WESTERN EUROPE; WESTERN EUROPE-GENERAL
Accession no.721744 Item 132 Kunststoffe Plast Europe 89, No.1, Jan.1999, p.20-3; p.68/72 RELIABLE PROCESSING OF LIQUID SILICONE RUBBER (LSR) INTO TECHNICAL MOULDINGS Haberstroh E; Henze E; Ronnewinkel C In a number of research projects, the IKV is working intensively with raw material and machine manufacturers as well as the processing industry on technologies for processing LSR. These activities are concentrating on process analysis and process development for injection moulding. Aspects covered include control of the quality of the moulding, process sequences in the pvT diagram, fuzzy logic for control of moulding weight, function of the fuzzy controller, effect of the control system, simulation of the flow and curing behaviour, multi-component injection moulding of LSR thermoplastic combinations, polyamide/ LSR composites and production of LSR components with functional cavities using the gas injection technique. 9 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.719224 Item 133 Biomaterials 20, No.3, Feb. 1999, p.291-9 EVALUATION OF THE IN VITRO BIOCOMPATIBILITY OF VARIOUS ELASTOMERS Chauvel-Lebret D J; Pellen-Mussi P; Auroy P; Bonnaure-Mallet M Rennes,Universite An evaluation is presented of the in vitro biocompatibility of silicone-based rubbers. The dimethylthiazol diphenyltetrazolium bromide colorimetric test was used to assess cell viability and flow cytometry was used to evaluate cell proliferation. Changes in cell morphology were examined using SEM. Comparisons were made with PU and PS toxicity controls. 28 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.714416
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Item 134 ACS Polymeric Materials Science and Engineering. Fall Meeting 1998. Volume 79. Conference proceedings. Boston, Mas., 23rd-27th Aug.1998, p.522. 012 ELASTOMERS FOR IMPLANTABLE APPLICATIONS - SILICONE OR POLYURETHANE ? Skalsky M Elastomedic Pty.Ltd. Medical device developers have had a very limited choice of implant materials for highly demanding applications such as insulation for pacing leads, long term in-dwelling catheters, synthetic polymer heart valves and coronary vascular grafts. All of these applications require polymers with excellent biostability, good mechanical strength and high resistance to fatigue, abrasion and tear. Traditionally, silicone rubber was the first material of choice, because of its excellent biostability, despite shortcomings in the other material properties. PU, a generic name for a very large family of synthetic polymers, has emerged as the principal alternative to silicone rubber because of superior mechanical properties. 7 refs. AUSTRALIA
Accession no.713300 Item 135 ACS Polymeric Materials Science and Engineering. Fall Meeting 1998. Volume 79. Conference proceedings. Boston, Mas., 23rd-27th Aug.1998, p.514. 012 CHEMISTRY OF SILICONE BASED BIOMATERIALS AND WHY THEY CONTINUE TO BE MATERIALS OF CHOICE FOR HEALTHCARE APPLICATIONS Petraitis D J NuSil Technology Since their early inception, materials based on silicone polymers have been characterised by their chemical inertness. Early silicone materials included greases which were formulated for insulating electrical ignition systems used by the military during World War II. Although their resistance characteristics were primarily concerned with weathering and other environmental factors such as ozone and high temperatures, this unique inertness of silicone polymer based materials ultimately evolved into biomedical applications. Silicone based materials were found to be extraordinarily inert to the chemicals present in biosystems. Silicones are among the most biocompatible materials known to man and today continue to outperform other materials in biomedical applications including applications in such diverse products as pacemaker leads, intraocular lenses, long and short term catheter and shunt implants, finger joint implants, as well as greases, lubricants, encapsulants and adhesives used in the fabrication, assembly or actual performance of an endless and continuing to be developed group of
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References and Abstracts
healthcare applications. The basic chemistry involved in the synthesis of silicone polymers and subsequent product formulations into elastomers, pressure-sensitive adhesives, marking inks, fluids and lubricants are discussed. USA
Accession no.713295 Item 136 Gummi Fasern Kunststoffe 50, No.12, Dec. 1997, p.967-73 German APPLICATION OF FOAM-IN-PLACE GASKETS Kayed J Instead of prefabricated shaped gaskets physically manufactured by stamping, injection moulding, extrusion etc., chemico-technical systems can be employed for the inline manufacture of precision gaskets (Foam-in-Place with partial or complete automation). This technique uses one-, two- or multi-component materials with the help of mixing and/or metering machines in the low-pressure range. The fluid compound applied produces a foam gasket with modifiable physical and chemical properties. At the same time the adhesion can be adjusted as required, from very high to zero or near zero. Data are given on the foaming mechanisms of polyurethanes, silicones and hotmelts for foam-in-place gaskets. 8 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.713240 Item 137 Rubber Technology International 1998, p.22-5 SILICONE RUBBER FOR ELECTRICAL INSULATORS Goudie J Dow Corning Corp. The market for composite insulators is growing steadily. Composite designs generally employ a fibreglass rod or hollow core for mechanical strength, with an outer housing made from either silicone rubber, EPDM or EPR. Insulator service life can be affected by electrical, mechanical and environmental stresses. One of the biggest problems in outdoor applications is airborne contamination that settles on the insulator surface. The surface of a silicone elastomer has a unique ability to interact with the contaminant and control leakage currents. 6 refs. USA
Accession no.713200 Item 138 IRC ’98. Conference Proceedings.
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Paris, 12th-14th May 1998, p.321-6. 012 French APPLICATIONS OF SILICONES IN ART Pujol J M Rhodia Silicones (AFICEP; Societe de Chimie Industrielle) Applications of silicone rubbers in moulds for the reproduction of works of art and in the assembly of glass objects and repair of stained glass windows are described. The use of silicone resins in the protection and restoration of ancient buildings and monuments is also examined. 1 ref. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.710626 Item 139 Gummi Fasern Kunststoffe 50, No.5, May 1997, p.376-85 German ROLLS AND ROLLERS Zeppernick F A historical survey is given of the development and use of polyurethane rubber in rollers and roller coatings, and of coating of rolls with silicone rubber. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.710477 Item 140 Polimery Tworzywa Wielkoczasteczkowe 42, No.5, 1997, p.288-93 Polish C0NTRIBUTION OF RESEARCH AND EXPERIMENTAL PRODUCTION AT ICRI TO THE DISSEMINATION OF SILICONE APPLICATIONS IN POLAND Rosciszewski P; Maciejewski J; Zielecka M; Miazga A; Paczka J; Porcja I Warsaw,Industrial Chemistry Research Institute A historical account is given of the research and development work carried out on the principal types of silicones that have been successfully commercialised at the Industrial Chemistry Research Institute’s Silicone Pilot Plant and at the OrganikaSarzyna Chemical Works. This includes work on fluids, emulsions, compounds, resins, varnishes, release agents, water-repellents for textiles and masonry, adhesives, antifoaming agents, and room-temperature vulcanising rubbers. 46 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. EASTERN EUROPE; POLAND
Accession no.710463
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References and Abstracts
Item 141 Analytical Chemistry 70, No.23, 1st Dec.1998, p.4974-84 RAPID PROTOTYPING OF MICROFLUIDIC SYSTEMS IN POLYDIMETHYLSILOXANE(PDMS) Duffy D C; McDonald J C; Schueller O J A; Whitesides G M Harvard University A procedure was developed for designing and fabricating (including sealing) microfluidic systems in an elastomeric material (PDMS) in less than 24 h. A network of microfluidic channels was designed in a CAD program. This design was converted into a transparency by a high-resolution printer and this transparency was used as a mask in photolithography to create a master in positive relief photoresist. PDMS cast against the master yielded a polymeric replica containing a network of channels. The surface of this replica and that of a flat slab of PDMS were oxidised in an oxygen plasma and these oxidised surfaces were shown to seal tightly and irreversibly when brought into conformal contact. 88 refs. USA
Accession no.709681 Item 142 Patent Number: US 5741877 A 19980421 SILICONE PSEUDOGEL Tiffany J S
Item 143 Journal of Biomedical Materials Research 42, No.4, 15th Dec.1998, p.485-90 CYTOTOXICITY TESTING OF MATERIALS WITH LIMITED IN VIVO EXPOSURE IS AFFECTED BY THE DURATION OF CELLMATERIAL CONTACT Ciapetti G; Granchi D; Stea S; Savarino L; Verri E; Gori A; Savioli F; Montanaro L Bologna,Istituti Ortopedici Rizzoli Extracts of six addition-type and six condensation-type silicone dental impression materials were tested with L929 cells according to ISO 10993-Part 5 standard. The cytotoxicity was evaluated by three different methods. Contact between cells and material extracts was maintained for 24 h in the first series of experiments but, as in vivo application of these materials is restricted to a few minutes, additional experiments were performed after 1 h of cell/extract contact. The addition-type silicones were found to be non-toxic even when tested after prolonged exposure of the cells to the materials while the condensation-type polymers were cytotoxic at 24 h of incubation. Most of the silicones were not toxic after 1 h. 16 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; ITALY; WESTERN EUROPE
Accession no.706452
A silicone gel-like material having reduced content of extractable silicone fluid and having rheological properties approximating human tissue. The gel-like material or “pseudogel” is useful for filling an implantable prosthesis. Prior art silicone gel-filled prosthetic implants contain a high proportion of extractable free silicone fluid. The free silicone fluid within an implant may enter the host’s body by diffusion through the prosthetic shell or by rupture of the outer envelope of the prosthesis. The present filler material, or pseudogel, is produced by controlling the crosslinking of the silicone polymer network such that every polymer chain contains only terminal reactive vinyl groups but not all of the reactive groups participate in the crosslinking reaction. In a preferred embodiment, the polymeric vinyl-terminated starting fluids are selected so that the average molecular weights of the polysiloxane polymers comprising the fluid may fall into two or three distinct ranges. The crosslinker, which is composed of a siloxane molecule containing silicone hydride groups, is selected to have relatively high Si-H content. By controlling the crosslinker concentration, essentially all the chains can be made to react, but in such a way that chains are only reacted at one end and functional as non-extractable diluents between the crosslinked longer chains. The resulting pseudogel exhibits low extractability and is suitable for filling a soft-tissue prosthesis such as a breast prosthesis having a flexible outer shell which contains the pseudogel.
Item 144 Nippon Gomu Kyokaishi 69, No.1, 1996, p.23-33 Japanese AIR BAGS -FOR COMFORTABLE DRIVING IN SAFETY Sakurai T; Ozaki T; Ushio M Toyo Gomu Kogyo KK
USA
Mechanical properties, abrasion characteristics, application areas and patented methods for improving the
Accession no.707845
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A discussion is presented of counter-measures taken to prevent accidents under modern traffic conditions, and of the development of air-bag systems and materials used in them such as silicone rubber. 10 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. JAPAN
Accession no.705847 Item 145 Nippon Gomu Kyokaishi 68, No.9, 1995, p.667-72 Japanese SILICONE RUBBERS Takahashi M Shin-etsu Chemical Industries Ltd.
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friction and abrasion characteristics of silicone rubbers are discussed. 31 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. JAPAN
Accession no.705426 Item 146 Nippon Gomu Kyokaishi 68, No.7, 1995, p.453-59 Japanese PROBLEMS OF ELASTOMERS USED IN MEDICINE Ikada Y Kyoto,University A classification of materials used in medical applications is given according to their physical capacities, and current problems relating to the use of polymer materials in medicine are discussed, with particular reference to silicone rubber, polyurethanes, natural rubber and plasticised PVC. 10 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. JAPAN
Accession no.704946 Item 147 Patent Number: US 5779964 A 19980714 METHOD OF MAKING A MALE CATHETER Welch D P; Ryan T D; Knutson E M Mentor Corp. The catheter has a condom-like sheath of silicone rubber sealingly engaging the penis of the patient. A catheter stem at the distal end of the sheath couples to a urine collection system. The sheath is sealed to the penis by an adhesive, which is applied to the outer surface of the sheath at the time of manufacture. A surface preparation layer is applied over the adhesive. The sheath is rolled up from the proximal end and unrolled to apply it to the patient. During the unrolling process, the adhesive layer is removed from the outer surface and deposited on the inner surface of the sheath. USA
Accession no.704566 Item 148 Gummi Fasern Kunststoffe 48, No.4, 1995, p. 249-251 German FLUOROSILICONE RUBBER - A VERY MODERN MATERIAL Klages D; Raupbach U Rado Gummi GmbH; GE Silicones A brief historical survey is presented of the use of silicon compounds, and some statistics are given on worldwide
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silicone rubber production. The author discusses processing of fluorosilicone rubbers and their properties, including resistance to fuels, oils and solvents, heat stability and good electrical properties. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.703558 Item 149 Gummi Fasern Kunststoffe 48, No.4, April 1995, p.244-248 German HOSES AND COUPLINGS Heitz E Basic properties are given of materials used in the manufacture of hoses and hose couplings - inner layers, reinforcements and covers. The materials covered are butyl rubber, chlorosulphonated polyethylene, ethylenepropylene rubbers, natural rubber, acrylonitrile-butadiene rubber, polychloroprene, polyether-urethane rubber and silicone rubber. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.703557 Item 150 Industria della Gomma 41, No.8, Oct.1997, p.37-8 Italian AUTOMATIC PRODUCTION UNIT FOR RUBBER-METAL ARTICLES Coscia M Rutil Srl The production of an automotive gasket using machinery developed by Rutil is described. The assembly consists of a glass fibre-reinforced polyamide base over which is moulded a silicone rubber gasket, and also incorporates a number of metal reinforcement washers. The production unit comprises a pair of C-frame injection presses, one for moulding the base and the other for overmoulding the gasket, with rotating tables for handling the parts, a station for loading the metal washers into the mould, and an industrial robot for checking the quality of the gaskets before unloading. EUROPEAN COMMUNITY; EUROPEAN UNION; ITALY; WESTERN EUROPE
Accession no.702481 Item 151 Patent Number: US 5665809 A 19970909
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References and Abstracts
EXTRUDED SILICONE GEL PROFILES Wojtowicz J Raychem Corp. A method is provided for making simple or complex extruded gel profiles and the created article. In a particularly preferred embodiment, the method involves the extrusion of a silicone gel composition through a die into a heated fluid to complete the cure of the gel as well as to produce the desired gel profile shape. Shapes such as stars, trapezoids, cusped squares, cusped triangle, triangles and the like can be fabricated. USA
Accession no.702431 Item 152 International Polymer Science and Technology 25, No.4, 1998, p.T/81-4 MAMMARY PROSTHESES WITH A POLYURETHANE SHELL Osorgina I V; Begishev V P; Kondyurin A V; Plaksin S A Perm,State University; Russian Academy of Sciences; Perm,Medical Academy The shell was manufactured from segmented PU based on an oligoether in the form of a copolymer of polyoxypropylene glycol and polytetrahydrofuran and 2,4-toluene diisocyanate. Curing was carried out with 3,3dichloro-4,4-diaminodiphenylmethane (Diamet Kh). The shell was filled with a low molecular weight silicone rubber of the SKTN-Med type. 10 refs. Translation of Plast.Massy, No.8, 1997, p.26 RUSSIA
Accession no.702190 Item 153 International Composites Expo ’98. Conference proceedings. Nashville,Tn., 19th-21st Jan.1998, Session 17-D. 627 ENHANCEMENTS IN RUBBER TOOLING/ COMPOSITE FABRICATION Thomas J E Tecnico Corp. (SPI,Composites Institute) A rubber tooling/composite fabrication process, where silicone rubber is utilised as part of the tool assembly, is described. The entire assembly of metal tool, rubber tool and composite material is contained by an outer mould. When heated, the rubber exerts pressure great enough to laminate composite parts. An autoclave or vacuum system is not required. Equations govern the sizing and expansion of the rubber and lead to theoretical pressures, which can be regulated. Tecnico has refined this process by utilising heat strips which are placed in critical locations in the mould. Conductive heating (vs. convection) allows faster cure cycles than conventional methods. By the addition
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or removal of heat strips, cold and hot spots in the mould are eliminated, which is crucial for control of the rubber pressure. The heating system also permits the composite to be cured in virtually any location, as long as there is electrical power. The process can be further improved by better heating methods and improved silicone rubbers that have higher operating temperatures, and could be recycled into the next rubber casting. Other improvements could be in the use of cooling systems allowing the mould assembly to return to ambient temperature in a minimal amount of time. 3 refs. USA
Accession no.702051 Item 154 154th ACS Rubber Division Meeting - Fall 1998. Conference preprints. Nashville, Tn., 29th Sept.-2nd Oct.1998, paper 12. 012 FASTER CURING LOW COMPRESSION SET NO POST CURE LIQUID SILICONE RUBBER Johnson E Wacker Silicones Corp. (ACS,Rubber Div.) The economies of the latest developments in liquid silicone rubber (LSR) materials and process technology make feasible the replacement of not only conventional heat cured silicone rubber, but also organic rubber in many applications. It is now possible to produce parts of at least 5 g in tools with over 30 cavities, with a production cycle of as little as 20 seconds. The latest cold runner tool and moulding press technology make it possible to produce parts with no waste and no flash. This same technology also makes possible continuous, fully automated production. Parts can be ejected from the mould into a box, ready for shipment with no need for deflashing. The combination of these factors is, in many cases, rapidly making older methods of moulded rubber part production uneconomical, despite the premium cost of the LSR material. Wacker has developed a unique and very effective method of preventing after cure that has been applied to a wide range of LSR products. The new generation of LSR will enable the production of parts that can behave like parts made from peroxide cure silicone rubber, but will be able to cure much faster. They are moulded in this fast, efficient operation without the need of any subsequent processing. USA
Accession no.701851 Item 155 Journal of Macromolecular Science C 38, No.4, 1998, p.637-50 REVIEW OF ELECTROSYNTHESIS OF POLYSILANE Subramanian K Vikram Sarabhai Space Centre
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References and Abstracts
A review of the literature on the electrosynthesis of polysilane is presented. The general procedure and monomer systems for electroreductive polymerisation are described, the mechanism of polysilane formation is considered and the reductive polymerisation of halosilanes in the presence of vinyl monomers is discussed. The review clearly demonstrates that, by a suitable choice of solvent, supporting electrolyte, dihalosilanes and complexing agent, the electroreductive formation of Si-Si and C-Si linkages can be used to synthesise ceramic-grade polysilane and polycarbosilanes, respectively, with less than 0.1 wt % oxygen and 20-75% yield of polymer. 45 refs. INDIA
Accession no.700969 Item 156 Rubber and Plastics News 28, No.3, 7th Sept.1998, p.6 LATEX-FREE CATHETER UNVEILED BY ROCHESTER McNulty M Rochester Medical has launched a latex-free silicone infection control catheter it believes will have a major impact on both the acute care industry and the company’s bottom line. The firm, which soon hopes to ready another innovative product for the market, has also named a new marketing and sales director. The maker of latex-free disposable urinary continence care products introduced Release-NF in May and June. The product has been in the testing and development stages for several years. Introduction of the product ‘is the most extensive marketing initiative the company has undertaken to date’. It is a silicone-advanced Foley catheter that delivers a controlled release of the antibacterial agent nitrofurazone, which is contained in the silicone matrix inside and outside the catheter. It is aimed at the acute care market and is the first and only latex-free Foley that works as a drug delivery system. Details are given. ROCHESTER MEDICAL CO. USA
Accession no.699940 Item 157 Kunststoffe Synthetics No.9, 1994, p.8-11 German WHERE HIGH TEMPERATURES ARE INVOLVED, RELIANCE IS PLACED ON SILICONES Fink P Wacker Chemie GmbH The use of liquid silicone rubber for injection moulding is described as an alternative to the solid material or other materials. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.699741
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Item 158 Machine Design 70, No.17, 24th Sept.1998, p.166/8 SILICONE-RUBBER HEATERS STRETCH PRODUCT UTILITY Cobb P Watlow Electric Mfg.Co.,Flexible Products Div. Novel applications for silicone rubber heaters are reported, and the versatility of the products are illustrated. Silicone rubber heaters can be shaped to fit most new products, and although many existing products can be modified, the best fit is achieved from working with heater specialists at the start of new design programs, it is suggested. The construction of a heater is described, together with and applications in heating frozen blood for transfusions, in marine applications, and heating a silicon wafer on a hot chuck for vacuum vapour deposition. USA
Accession no.699576 Item 159 Plast’ 21 No.63, Sept.1997, p.34 Spanish EXTENDED USE OF SILICONES IN THE CAR A review is presented of automotive applications of Bayer’s Silopren range of liquid and solid silicone rubbers. BAYER AG EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.698945 Item 160 Rubber World 218, No.6, Sept.1998, p.20/69 PROCESSING GUIDE TO SILICONE RUBBER EXTRUSIONS Taylor T C Specialty Silicone Products Inc. This article is the second part of a series providing a processing guide to silicone rubber extrusions. Screen packs and breaker plate, feeding, screw designs, screw flight design, and dies and guiders are discussed. A troubleshooting chart is presented. USA
Accession no.698783 Item 161 Journal of Coated Fabrics 27, April 1998, p.326-37 NEW GENERATION OF SILICONE ELASTOMERS FOR AIRBAG COATINGS Bohin F; Pouchelon A; Surprenant R Rhone-Poulenc Silicones
© Copyright 2001 Rapra Technology Limited
References and Abstracts
In 1996, a new generation of silicone elastomers for coating was launched on the European market. Specifically designed to meet the airbag market, these new products have specific rheological properties allowing very thin coatings without any change in the technology or use of a solvent, giving significant cost reduction for the customer. Giving improved thermal protection to the fabric, they are very well adapted to the new generation of airbag inflators arising from the market. Their specific properties also provide a 100% increase of the fabric tear strength. 6 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.697986 Item 162 Patent Number: US 5767183 A 19980616 HEAT SHRINKABLE SILICONE TUBE AND METHOD FOR MAKING Takei H; Shimamoto N; Ohtsuka Y Shin-Etsu Chemical Co.Ltd. This tube is made from a silicone rubber composition comprising a diorganopolysiloxane, a thermoplastic resin, finely divided silica, an inorganic filler of titanium white, alumina, quartz powder or talc having a mean particle size of 0.5 to 15 micrometers and a curing agent by extrusion moulding, preferably at a drawdown of 150 to 250%, vulcanisation and heat stretching in a radial direction. It exhibits axial orientation during stretching and shrinking subsequent thereto and is thus tearable. JAPAN
Accession no.697587 Item 163 RubberTech China ’98. Conference proceedings.. Shanghai, China, 24th-26th March, 1998, paper 17. 012 PROPERTIES AND APPLICATION OF SILICONE RUBBERS (HCR AND LR) Beisswenger H Wacker Chemie GmbH (Rapra Technology Ltd.; Crain Communications Ltd.) The properties, applications, curing and processing of silicone rubbers are discussed, with particular reference to the differences between HCR (millable type) and LR (liquid rubber). The comparisons between the two types of rubber illustrate advantages and limitations for using liquid silicone rubbers. Applications in automotive, personal care products, keypads, baby teats and catheters are described. CHINA; EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.696400 Item 164 Patent Number: US 5735985 A 19980407
© Copyright 2001Rapra Technology Limited
METHOD FOR MICROMOULDING CERAMIC STRUCTURES Ghosh S K; Furlani E P; Grande W J Eastman Kodak Co. Ceramic articles and structures having spatial features as small as 0.1 micrometer and having a depth ranging from 2.0 to 100 micrometer are micromoulded using a master mould of the article or structure to be moulded and fabricated utilising a silicon wafer and dry etching technology. A negative master mould is then produced by placing the silicon master mould device in a surrounding mould form and filling the mould form with a silicone or silicone rubber, preferably a RTV silicone rubber. Such material replicates each of the micro features of the master mould in great detail to a resolution of the order of 0.1 micrometer. The negative master mould is then used in a die to mould the desired individual elements or structures from a ceramic powder, which is capable of replicating each of the micro features of the negative master mould to the desired resolution. USA
Accession no.695131 Item 165 Patent Number: US 5656690 A 19970812 ORGANOPOLYSILOXANE COMPOSITIONS WHICH CROSSLINK TO GIVE ELECTRICALLY CONDUCTIVE ELASTOMERS Pradl F; Fink P; Noemmer K; Birneder R Wacker-Chemie GmbH The invention relates to organopolysiloxane compositions that when crosslinked form electroconductive elastomers. The elastomers are formed via an addition crosslinking method and contain 11-30 wt % with respect to the total composition of carbon fibres having 0.1-10 mm average length. The compositions are suitable for producing injection moulded articles. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.690309 Item 166 Rubber and Plastics News 27, No.23, 15th June 1998, p.28 DOW CORNING FORMULAS AID TWO HOSE MAKERS Wilson E Two companies are finding Dow Corning STI’s new advances in silicone technology key ammunition in their fight against coolant hose wear and tear. Flexfab Horizons International and Thermopol are finding success in utilising Dow Corning custom silicone formulations that markedly sustain elastomeric hose endurance under repeated exposure to rigorous pressure and temperatures. Using the formulations, Flexfab has reported an increase
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of 50% in the life of its heater and radiator hoses for Class 8 trucks. The firm now offers a warranty on its hoses for up to 1.5 million miles. As under-the-hood temperatures rise, cooling system hoses expand, increasing pressure exerted upon them by metal stems to which they are clamped. After cool-down, hose stems thin, caused by this pressure, resulting in a gradual loss of sealant integrity over extended periods of use. This loss is known as cold leak. While the compression set of EPDM has been measured by Society of Automotive Engineers coolant hose specifications at 75-85%, and that of generic silicone at 40%, the elastomeric bulk loss of Dow’s custom formulated compound is 25%. Details are given. DOW CORNING STI; FLEXFAB HORIZONS INTERNATIONAL; THERMOPOL INC. USA
Accession no.689777 Item 167 Journal of Biomaterials Applications 13, No.1, July 1998, p.66-73 PROPERTIES OF MAXILLOFACIAL SILICONE ELASTOMERS REINFORCED WITH SILICA POWDER Andreopoulos A G; Evangelatou M; Tarantili P A Athens,National Technical University Compounds of a silicone elastomer reinforced with various amounts of silica powder, which were suitable for preparing maxillofacial prostheses, were studied for their mechanical response and wetting properties in terms of contact angle. TS and EB showed an increase with increasing silica volume fraction up to 35%, whereas the Young’s modulus displayed a slight dependence on the silica content and the resistance to tear increased continuously with filler volume fraction (Vf). The wetting properties, assessed via the contact angle, seemed to degrade with increasing Vf, but a dependence on the elastomer network density was also recorded. 10 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GREECE; WESTERN EUROPE
Accession no.688759 Item 168 Journal of Coated Fabrics Vol.27, Jan.1998, p.219-36 PRECISION PLACEMENT OF THIN POLYMERIC SILICONE FILMS WITHIN FABRICS Meirowitz R Nextec Applications Inc. Nextec patented technology is described which allows for the precision placement of thin polymeric films around fibres, crossover points and filling in or leaving open interstitial spaces within fabrics. The choice of polymer, substrate and placement of polymer is shown to allow for improvement of properties, such as breathable barrier
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performance, controlled porosity, resistance to fluids and adhesion/release behaviour. Applications of the technology in apparel, automotive, aerospace and medical fields are described. The benefits in these applications are delivered in a process that has no volatile organic compounds and yields inert residual materials. Examples of materials and comparative performances are discussed. 7 refs. USA
Accession no.688755 Item 169 Kautchuk und Gummi Kunststoffe 51, No.6, June 1998, p.410/5 German LIQUID SILICONE RUBBER - PROPERTIES AND APPLICATIONS Jerschow P Liquid silicone rubber is used to produce elastic parts by injection moulding. Its main properties range from high resistance against temperatures (both high and low temperatures) and chemicals to high transparency and good mechanical properties. It is used in automotive parts, electronics, medical devices, food and household appliances and many other sectors. Liquid silicone rubber is processed fully automatically in an injection moulding machine. The applications, processing and properties of liquid rubber are summarised. 5 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.687926 Item 170 Patent Number: US 5693689 A 19971202 MONITOR PUTTY WITH INCREASING STIFFNESS Gibbon R M JMK International Inc. An exercise putty kit providing manipulative physical therapy of increasing difficulty comprises a container of a large mass of borosiloxane putty and a package of borosiloxane or siloxane putty. At least one small mass is provided to the patient along with the large mass, the small mass and large mass being manipulated by the patient until a uniform colour and stiffness are achieved in the combined mass. Preferably, a plurality of small masses having a variety of colours are available for successive manipulation with the combined mass. The kit provides a means by which the difficulty of manipulative physical therapy may be monitored and increased. As more small masses are added to the combined mass, the stiffness increases, requiring more manipulation to fully blend the masses. USA
Accession no.687072
© Copyright 2001 Rapra Technology Limited
References and Abstracts
Item 171 International Polymer Science and Technology 24, No.12, 1997, p.T/9-13 NEW TECHNIQUES IN EXTRUSION AND VULCANISATION Colombo U Brief details are given of new extrusion and vulcanisation systems and techniques. Some data are given for the extrusion of hoses and sections made from silicone rubber and extrusion lines for the manufacture of elbow hose blanks. Translated from Gummi Fas Kunst, No.10, 1997, p.804 Accession no.684804 Item 172 Journal of Biomedical Materials Research (Applied Biomaterials) 43, No.2, Summer 1998, p.99-107 BIOCOMPATIBILITY RESPONSE TO MODIFIED BAERVELDT GLAUCOMA DRAINS Jacob J T; Burgoyne C F; McKinnon S J; Tanji T M; LaFleur P K; Duzman E Louisiana,State University Details are given of the modification of a Baerveldt glaucoma filtering device made of silicone rubber by adding porous cellular ingrowth material to the posterior surface of the drainage plate. These materials were implanted and their biocompatibility was investigated. 33 refs. USA
ELASTOMER UNDER DIFFERENT AXIAL LOADING CONDITIONS Abel E W; Wheeler K I; Chudek J A; Hunter G; Som F M Dundee,University Results are presented of tests on axially tensioned silicone elastomer tendon spacer samples to determine the relationship between stress in the material and image intensity. Images were obtained using spin echo, gradient echo and magnetic resonance imaging snapshot techniques. 15 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.681411 Item 175 Advanced Materials & Processes 153, No.5, May 1998, p.6 VERY SPECIAL CARS BOAST SPIN-CAST PARTS Metalcrafters builds one-of-a-kind automobile prototypes. The company was helped by Chrysler to get its business off the ground with a request for road-worthy metalbodied prototypes. In a bid to find a faster way to produce low to medium volumes of smaller parts like emblems, air vents, door handles and dashboard knobs, Metalcrafters turned to spin casting. Silicone rubber moulds can produce up to 1500 parts, the company claims. METALCRAFTERS USA
Accession no.680676
Accession no.682945 Item 173 Macplas International Feb.1998, p.42-3 LIQUID RUBBER MIR has perfected its injection moulding machines devoted to liquid silicone rubber, achieving the production of very small to medium size parts of excellent quality at competitive prices. LSR has high electrical insulation properties, high resistance to extremes of temperature, long life, and is non-toxic, non-allergenic and biocompatible. LSR brings benefits from advanced processing technology. Manufacturers can obtain consistent material savings in terms of scrap, flash and runners. MIR SPA EUROPEAN COMMUNITY; EUROPEAN UNION; ITALY; WESTERN EUROPE
Accession no.682023
Item 176 Rubber and Plastics News 27, No.19, 20th April 1998, p.6 AMERICAN BIOMED CATHETER GAINS CLEARANCE McCann J American BioMed Inc. is reported to have gained clearance from the FDA for a new silicone rubber thrombectomy catheter that removes blood clots from blood vessels. A description is given of the Ahn catheter, which is expected to be launched in this year’s second quarter, and a US patent on the device is expected during the next two months. Its design consists of a three balloon type, which is said to give surgeons more inflation control during operations and helps prevent blood spattering when it’s removed. It is the company’s first internally developed product to make it through the FDA process on a fully independent basis, it is reported. AMERICAN BIOMED INC. USA
Item 174 Biomaterials 19, Nos 1-3, 1998, p.55-60 ANALYSIS OF MRI IMAGES OF A SILICONE
© Copyright 2001Rapra Technology Limited
Accession no.680170 Item 177 Journal of Macromolecular Science C
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C38, No.2, 1998, p.143-205 SOME HETEROCYCLIC POLYMERS AND POLYSILOXANES Lu F Academia Sinica A review is given of research into several important heterocyclic polymers with emphasis given to polyphenylquinoxalines, polytriazines, polypyrrolones, polyimides, polyamide-imides, polybenzimidazoles, and polysiloxanes. Details are given of the synthesis of new monomers and polymers and the development of new synthetic routes. The thermal degradation, pyrolysis and hydrolysis at high temperature are discussed. 162 refs. CHINA
Accession no.679421 Item 178 Journal of Polymer Science : Polymer Physics Edition 36, No.6, 30th April 1998, p.1091-4 ELECTRORHEOLOGICAL FLUID AND SILOXANE GEL BASED ELECTROMECHANICAL ACTUATOR: WORKING TOWARD AN ARTIFICIAL MUSCLE Bohon K; Krause S Rensselaer Polytechnic Institute A device has been developed to simulate muscle operation with the time response of the order of a striated skeletal muscle. 8 refs. USA
Accession no.678661 Item 179 Modern Plastics International 28, No.4, April 1998, p.64-5 NEW FORMULATIONS, PROCESS TECHNOLOGY PROPEL SILICONE MOULDING Smock D Recent advances in polymer formulations and process technology are propelling a boom in liquid silicone moulding. It is claimed that companies can attain significant reductions in total part costs with liquid injection moulding compared with processing heat-cured elastomers. One development at GE Silicones is lowcompression-set formulations that open opportunities in automotive applications for moulders seeking ways to add value to existing business. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; USA; WESTERN EUROPE
Accession no.678253 Item 180 Injection Molding 6, No.2, Feb.1998, p.53 USING LIM TO CREATE BETTER, FASTER,
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CHEAPER PROTOTYPES This article highlights an injection moulding process that has been developed by Vesta Inc. of the USA, intended to put an end to lengthy, expensive prototype production of medical products. “Quick Response” uses liquid injection moulding (LIM) equipment to mould medicalgrade liquid silicone rubber in low volumes. VESTA INC. USA
Accession no.677267 Item 181 Kunststoffe Plast Europe 87, No.10, Oct.1997, p.46-8 English; German LIQUID SILICONE RUBBER Pohmer K; Schmidt G; Steinberger H; BruendL T; Schmidt T In this paper, liquid silicone rubber is placed under the spotlight, and its properties, processing methods (liquid injection moulding, multi-component injection moulding, as well as modifying and finishing), and typical applications are all considered. EUROPE-GENERAL; EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE; WORLD
Accession no.676699 Item 182 Patent Number: EP 832936 A1 19980401 PHOTOCURABLE LIQUID SILICONE RUBBER COMPOSITIONS FOR TEMPLATING MOTHER MOULDS Fujiki H; Sakamoto T Shin-Etsu Chemical Co.Ltd. The cured products have a Shore hardness of 20 to 60 and a light transmittance of at least 10% at a wall gauge of 10 mm. A photocurable liquid resin cast into the mould is cured with light transmitted by the mould wall. JAPAN
Accession no.675916 Item 183 Macromolecular Symposia No.127, Feb.1998, p.205-9 COMPOSITE MATERIAL FOR MEDICAL APPLICATION Zamyslov E V; Klochkov V I; Ostrovidova G U St.Petersburg,Institute of Technology Details are presented of the preparation of graphite filled PDMS for medical applications. The physico-chemical and mechanical properties were determined. Predicted thromboresistance is discussed. 22 refs. RUSSIA
Accession no.672899
© Copyright 2001 Rapra Technology Limited
References and Abstracts
Item 184 Journal of Microencapsulation 15, No.2, March-April 1998, p.227-36 PREPARATION OF SILICONE MICROSPHERES BY EMULSION POLYMERIZATION: APPLICATION TO THE ENCAPSULATION OF A HYDROPHILIC DRUG Kedzierewicz F; Darme X; Etienne A; Lemut J; Hoffman M; Maincent P Nancy I,University; Dow Corning The ability of suitable silicone elastomers to encapsulate hydrophilic compounds in microspheres prepared according to a multiphase emulsion-polymerisation process was evaluated. The particle size of the microspheres could be modified by controlling the usual emulsification parameters, such as the viscosity of the different phases, shear rates and surface activity properties of additives. The encapsulation efficiencies of a hydrophilic drug, propranolol hydrochloride, were very high but its release rates were very slow. Osmotic agents such as glycerol and propylene glycol did not enhance the release rate, whereas it was slightly increased by both sodium chloride addition and higher drug loading. 11 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.671085 Item 185 Plastiques Modernes et Elastomeres 48, No.7, Sept.1996, p.38/41 French SILICONE RUBBERS: PROCESSING, PROPERTIES AND APPLICATIONS Vasselle J B The processing, vulcanisation, properties and applications of hot curing and liquid silicone rubbers are reviewed, and applications of liquid silicone rubbers in injection and insert moulding are examined. Statistics are presented for world consumption of silicone rubbers. BAYER AG; GE PLASTICS EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; USA; WESTERN EUROPE; WORLD
Accession no.670761 Item 186 Journal of Biomedical Materials Research (Applied Biomaterials) 43, No.1, Spring 1998, p.1-14 INFLUENCE OF PDMS SURFACE TEXTURE ON HUMAN SKIN FIBROBLAST PROLIFERATION AS DETERMINED BY CELL CYCLE ANALYSIS van Kooten T G; Whitesides J F; von Recum A F Clemson,University The interaction of human fibroblasts with silicone surfaces was studied using cell cycle analysis. The potential of cell cycle analysis to serve as an integrated
© Copyright 2001Rapra Technology Limited
tool in models for biocompatibility assessment in vitro is discussed. 27 refs. USA
Accession no.670595 Item 187 Surface Coatings International 81, No.2, Feb.1998, p.89-93 MASONRY PROTECTION WITH SILANES, SILOXANES AND SILICONE RESINS Mayer H Wacker-Chemie GmbH The use is discussed of silanes, siloxanes and silicone resins in the masonry protection field, where they act as binders in decorative coatings or as water-proofing agents. An overview is presented of applications, product classes and other modes of action. Applications considered include silicones in masonry paints and plasters, where they work as binders, additives or primers, in construction chemicals, where they work as water and oil repellents, damp-proofing agents or stone strengtheners, in in-plant produced materials such as roof tiles and gypsum boards, where they work as water repellents for after-treatment applications or for core-treatment applications. The suitability of a single product class of these silicone masonry water repellents based on silanes, siloxanes and silicone resins are discussed for the above applications. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.669231 Item 188 Journal of Biomaterials Applications 12, No.3, Jan.1998, p.258-71 BIOMEDICAL SILICONE ELASTOMERS AS CARRIERS FOR CONTROLLED RELEASE Andreopoulos A G; Plytaria M Athens,National Technical University The potential of biomedical siloxane elastomers as carriers for controlled release of drugs was assessed. A two-component silicone gel system was used and various crosslinking agent ratio was applied in order to produce networks with varying crosslink density. Swelling experiments in toluene were conducted in order to evaluate the network characteristics. The silicone elastomer was loaded with salicylic acid and propanolol hydrochloride and their delivery in distilled water was followed. The results showed that release was almost of zero order for high loading of salicylic acid, while delivery seemed to be diffusion-controlled up to a certain limit. The drug concentrations administered were relatively low if silicone discs were used, due to the hydrophobic nature of this material. When membranes with a thickness of 0.1-0.2 mm were used, on the other hand, the delivery rate was much
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higher depending, of course, on the hydrophilic character of the drug. 18 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GREECE; WESTERN EUROPE
Accession no.668285 Item 189 Rubber World 217, No.3, Dec.1997, p.42-4 SILICONE POLYMERS FOR HIGH-VOLTAGE INSULATORS Owen M J Dow Corning Corp. Composite insulators with sheds moulded from silicone rubber have been used in high-voltage service for nearly 30 years and their popularity is on the rise. Silicone compounds retain hydrophobicity better than ceramics or glass, especially in coastal regions and contaminated areas. Composite insulators are lightweight and can significantly reduce losses from breakage and vandalism. Much of the current work on the newest generation of silicone insulators focuses on surface chemistry to better understand the effects of long-term ageing and electrical discharge. 9 refs. USA
This includes a diorganopolysiloxane terminated with a hydroxyl group at both terminal ends and having a viscosity at 25C of 25 to 1,000,000 cSt, an organosilane having 3 or more hydrolysable groups (ketoxime or alkenyloxy groups) per molecule, a partially hydrolysed and condensed product thereof or a mixture thereof and a thin leaf-like inorganic filler. Cured products based thereon have good oil resistance and are suitable as FIPG materials for automobiles. JAPAN
Accession no.665650 Item 192 Rubber and Plastics News 27, No.3, 8th Sept.1997, p.11 NOT DUMB LUCK Campanelli J This article relates the story of how Kathryn Krotseng created a patented silicone moulding process (the inversion moulding system or IMS) to make mannequins. Silicone mannequins, as opposed to PU dummies, are noncorrosive, non-toxic, and non-flammable. The IMS process is described. MANNI-KIT INC. USA
Accession no.668231
Accession no.665007
Item 190 Patent Number: US 5639416 A 19970617 METHOD OF MOULDING PRECISION PARTS Pennisi R W; Jackson G D; Urbish G F; Megleo L D Motorola Inc.
Item 193 Plastiques Flash No.287, Jan./Feb.1996, p.70-1 French STATE OF THE ART IN MOULDING LIQUID SILICONES
This low pressure injection moulding method uses a twopiece silicone rubber mould having a cavity representative of the shape of the article to be moulded. The mould is substantially encased on all sides in a rigid mould box to prevent deformation of the cavity during the moulding process. The mould box and the encased mould are placed in a vacuum chamber and a vacuum is drawn on the chamber to evacuate the cavity. A predetermined amount of a reactive mixture is simultaneously mixed and injected under pressure into the mould to form the article. The amount of material injected is sufficient to fill the cavity but not sufficient to distort the cavity. The chamber is vented and the mould is removed from the mould box. The mould is then flexed to remove the article therefrom. USA
Accession no.667840 Item 191 Patent Number: EP 816436 A1 19980107 ROOM TEMPERATURE CURABLE ORGANOPOLYSILOXANE COMPOSITION Kimura T; Suzuki K; Teshigawara M Shin-Etsu Chemical Co.Ltd.
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The Arburg Allrounder 120 V-40 injection moulding machine and its use in the manufacture of prototype automotive components from liquid silicone rubbers are described. ARBURG MASCHINENFABRIK; WOCO; EOC NORMALIEN EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.663471 Item 194 Revista de Plasticos Modernos 70, No.472, Oct.1995, p.379-81 Spanish MCP VACUUM CASTING SYSTEM MCP Iberia SA Details are given of the MCP vacuum casting system for the production of plastics prototypes using silicone rubber moulds. EUROPEAN COMMUNITY; EUROPEAN UNION; SPAIN; WESTERN EUROPE
Accession no.663464
© Copyright 2001 Rapra Technology Limited
References and Abstracts
Item 195 Analytical Chemistry 69, No.23, 1st Dec.1997. p.4912-6 RELEASE OF LOW MOLECULAR WEIGHT SILICONES AND PLATINUM FROM SILICONE BREAST IMPLANTS Lykissa E D; Kala S V; Hurley J B; Lebovitz R M Baylor College of Medicine A series of studies was conducted addressing the chemical composition of silicone gels from breast implants as well as the diffusion of low molecular weight silicones and heavy metals from intact implants into various surrounding media, namely lipid-rich media (soy bean), aqueous tissue culture medium (modified Dulbecco’s medium, DMEM), or an emulsion consisting of DMEM plus 10% soy oil. The rates at which LM-silicones and platinum leaked through the intact implant outer shell into the surrounding media under a variety of conditions were studied. 14 refs. USA
Accession no.662917 Item 196 Rubber and Plastics News 27, No.8, 17th Nov. 1997, p.10 NEW COMPANY LAUNCHES NON-METAL HEAD GASKET Meyer B A high temperature, non-metallic head gasket has been developed that is competitive with metal gaskets. Developed by William A. Clarke, a former Ford Motor engineer, it consists of silicone rubber, which he describes as a pre-ceramic polymer, and a key part of the material is said to be the fibre reinforcement from Owens Corning which is claimed to have unusually low thermal expansion. Clarke’s company is called Gasket King: A Briefer Clark Company L.L.C., and is currently operating by using excess capacity at Edler Industries’ plant under a government program to fund the development of peacetime products at factories primarily geared toward defence work. GASKET KING: A BRIEFER CLARK CO.LLC; DELER INDUSTRIES USA
Accession no.662690 Item 197 Medtec. Conference proceedings. Amsterdam, 21st-23rd Oct.1997, Session 102, Thomas, p.1-6. 6S BIOPERFORMANCE OF SILICONE MATERIALS IN BIOMEDICAL APPLICATIONS Thomas X; Briquet F Dow Corning Corp. (Canon Communications Inc.) The use of polymers for biomedical applications has been dramatically expanding during the last decades. As
© Copyright 2001Rapra Technology Limited
biomaterials, they now play an essential role in helping healthcare workers to save life, alleviate pains and improve the general quality of life. Several guidelines and test methods ensure that adequate information exists regarding the function of the device and its toxicity profile to define its risk to benefit ratio. However, beyond the legal requirement, which allows to qualify biocompatible materials against industrial ones, there is still an opportunity for performance improvement in specific applications and thus the differentiation of some biomaterials to offer substantial benefits. The concept of BioPerformance is introduced and illustrated with three comparative examples which highlight the unique contribution of recognised silicone products to selected biomedical applications. 13 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.662523 Item 198 Journal of Biomedical Materials Research 37, No.4, 15th Dec.1997, p.539-47 EFFECT OF SUBCUTANEOUS SILICONE RUBBER IMPLANT WITH SHALLOW SURFACE MICROGROOVES ON SURROUNDING TISSUES IN RABBITS den Braber E T; de Ruijter J E; Jansen J A Nijmegen,University It has been suggested that during wound healing, microtextured surfaces can alter events at the interface between implant surface surface and surrounding tissues. To investigate this phenomenon, smooth and microtextured silicone rubber implants are implanted subcutaneously in rabbits for 3, 7, 42 and 84 days. The textured implants possess parallel surface microgrooves and ridges with a width of 2.0, 5.0 and 10.0 micrometer. All grooves have a depth of approximately 0.5 micrometer. SEM observation shows fibroblasts, erythrocytes, lymphocytes, macrophages, fibrin and collagen on all implant surfaces after three and seven days. After 42 and 84 days only little collagen, a small number of fibroblasts, but no inflammatory cells are seen on the implant surfaces. The fibroblasts are not oriented along the surface grooves on all textured surfaces. Three-dimensional reconstruction of CLSM images and LM images show no significant differences between the thickness of the capsules surrounding the smooth and those surrounding the microgrooved implants. In contrast, LM does show a significantly lower number of inflammatory cells and a significantly higher number of blood vessels in the capsules surrounding the microgrooved implants. Differences between the 2.0, 5.0, and 10.0 (m grooved implants are not detected. Results concerning capsule thickness suggest that the depth of the grooves is not sufficient to facilitate mechanical interlocking, but the cause for the observed differences in inflammatory response and number of blood vessels remains unclear. 29 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; NETHERLANDS; WESTERN EUROPE
Accession no.662315
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Item 199 Journal of Biomedical Materials Research 37, No.4, 15th Dec.1997, p.534-8 ADJUVANCY EFFECT OF DIFFERENT TYPES OF SILICONE GEL Naim J O; Ippolito K M L; van Oss C J Rochester,General Hospital; Buffalo,University Women with silicone gel-filled breast implants (SBIs) are likely to be at a slightly higher risk of developing an autoimmune-like syndrome. This risk, although small, may be associated with the immunological adjuvancy property of the silicone gel. However, not all silicone gels are chemically formulated exactly the same and their adjuvancy behaviour may vary. This e adjuvant effect of three different lots of silicone gel is compared in rats, using ovalbumin (OVA) as the test antigen. Test bleeds are taken at 21, 48, 62 and 84 days post immunisation and the rat sera are analysed for anti-OVA antibodies by enzyme-linked immunosorbent assay (ELISA). A delayed type hypersensitivity (DTH) test is performed on all the treated rats beginning at 14 post-immunisation days. The results show that silicone gel No.3 (McChan lot no. S0400488) produces the highest mean anti-OVA antibody titre followed by silicone gel No.1 (DC lot No. HHO19581) and silicone gel No.2 (McChan lot No. 13P9339). The DTH results show that rats treated with silicone gel 1 and 3 have a clear positive response, whereas silicone gel 2 causes only a minimal response. These results demonstrate the immunological adjuvancy difference among three types of silicone gel. The chemical composition of each of these silicone gels, that would help explain these results, is yet to be determined. 12 refs. USA
Accession no.662314 Item 200 152nd ACS Rubber Division Meeting, Fall 1997. Conference Preprints. Cleveland, Oh., 21st-24th Oct.1997, Paper 96, pp.32. 012 BASIC STUDY OF CONTINUOUS ULTRASONIC DEVULCANIZATION OF UNFILLED SILICONE RUBBER Diao B; Isayev A I; Levin V Yu Akron,University,Inst.of Polym.Engineering (ACS,Rubber Div.) Unfilled polydimethyl siloxane vulcanisates were ultrasonically devulcanised under several processing conditions in an extruder with an ultrasound die attachment. Gel fraction and crosslink density measurements indicated that the rubber was partially devulcanised. The cure behaviour, rheological properties and structural characteristics of the devulcanised and virgin rubbers were studied, and the mechanical properties of revulcanised samples were compared with those of the virgin rubber. GPC results implied that the creation of a branched structure in the network was possible after
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devulcanisation. Revulcanisation of rubbers devulcanised under optimal conditions gave mechanical properties better than those of the virgin rubber. Blends of devulcanised and virgin rubbers showed the same tensile strength and modulus as the virgin rubber but higher elongation. 16 refs. USA
Accession no.659540 Item 201 Patent Number: US 5616647 A 19970401 ONE PART ROOM TEMPERATURE VULCANISING COMPOSITION HAVING BOTH A HIGH RATE OF EXTRUSION AND LOW SAG Dziark J J; Pink M R; Martucci J P General Electric Co. A base mixture of a diorganopolysiloxane and an end stopping crosslinking ketoximosilane are reacted prior to being added to a first injection port along an extruder. An inorganic filler is added to the base mixture at a second injection port along the extruder, an M stopped silicone fluid is partitioned into two parts and the first part of the M stopped fluid is added to the filler containing base mixture at a third injection port at the middle of the extruder. A tin catalyst, an adhesion promoter and the second part of the M stopped fluid is added at a fourth injection port along the extruder and the mixture is extruded towards the extruder exit port. USA
Accession no.658578 Item 202 152nd ACS Rubber Division Meeting, Fall 1997. Conference Preprints. Cleveland, Oh., 21st-24th Oct.1997, Paper 30, pp.11. 012 LR3014 SERIES: A NEW FAMILY OF LIQUID SILICONE RUBBER FOR OUTSTANDING, NO POST CURE PERFORMANCE IN OIL SEALING APPLICATIONS Johnson T Wacker Silicones Corp. (ACS,Rubber Div.) Applications of liquid silicone rubber (LSR) in injection moulded automotive seals and gaskets are examined, and results are presented of a study which was undertaken to compare the performance of a conventional LSR compound with that of a grade in the Elastosil LR3014 series (Wacker Silicones) which employs a method of controlling aftercure without post curing. This new grade showed advantages in terms of reduced compression set, greater heat resistance, equivalent resistance to motor oils and equivalent to substantially improved resistance to different types of transmission fluids. USA
Accession no.658284
© Copyright 2001 Rapra Technology Limited
References and Abstracts
Item 203 Biomedical Materials Oct. 1997, p.10-11 SILICONE IMPLANTS The use of silicone in testicular implants has declined following the moratorium on the use of silicone breast implants by the FDA, it is reported. Problems regarding the presence of impurities in the silicone polymer such as silica which was used to harden the elastomer, platinum which acted as the catalyst, and a variety of organic and inorganic compounds including talc have been implicated in inciting an inflammatory response in the recipient which is difficult to avoid, claim scientists. In addition, the rarity of connective tissue diseases and the long latency period mean that the definitive epidemiological study to detect an association between silicone implants and connective tissue disease, may never be performed, it is argued. USA
Accession no.655797 Item 204 Kunststoffe Plast Europe 87, No.9, Sept. 1997, p.41-2 LIQUID SILICONE RUBBER (LSR) CAPS Emmerichs H; Giesler D EOC Normalien The injection moulding of liquid silicone rubber caps using a 16 cavity mould with a cold runner system, is described. The cap is for protecting the power door lock switch in a car from moisture and dirt. It is stated that the low viscosity of liquid silicone rubber requires special precautions with respect to design and operations of injection moulds, and the use of a standard cold runner system is said to simplify processing. It is advised that care should be taken to provide proper thermal separation of the runner system from the part forming sections of the mould, but that demoulding of parts with small undercuts should not cause problems. Details are given of the mould design and the runner system, and part release/ejection. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.655713 Item 205 Journal of Biomedical Materials Research 36, No.4, 15th Sept.1997, p.487-97 EFFECT OF SALINE EXPOSURE ON SURFACE AND BULK PROPERTIES OF MEDICAL GRADE SILICONE ELASTOMERS Kennan J J; Peters Y A; Swarthout D E; Owen M J; Namkanisorn A; Chaudhury M K Dow Corning Corp.; Lehigh University Medical grade silicone elastomers are subjected to accelerated ageing in saline to verify the hydrolytic
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stability of the elastomer. Tensile strength, elongation at break and elastomer stress measured at 100% or 200% elongation do not change significantly for peroxide-cured sheeting aged in 37 deg.C or 100 deg.C saline for 45 h. Under similar conditions, hydrosilylation cured sheeting behaves similarly; however, increases in stresses measured at 100% and 200% elongation are observed after the first hour of treatment. After the first hour, the physical properties remained relatively constant. On either elastomer, initial liquid drop advancing contact angles for water ranges from 110-115 deg., and in no case is a change of more than 6 deg. observed as a result of ageing in saline for 45 h at temperatures up to 97 deg.C. The high advancing angles indicated that the surface remains largely hydrophobic. Initial liquid drop receding contact angles range from 48-64 deg., with receding contact angles being more sensitive to accelerated ageing, in one case decreasing to 14 deg. Similar decreases in receding contact angle are observed in PE subjected to the same accelerated ageing conditions. Decreases in receding contact angle are not considered to be indicative of extensive hydrolysis. The observed contact angle phenomena are consistent with current views of contact angle hysteresis being caused by surface heterogeneity. There is no evidence of significant surface or bulk siloxane hydrolysis under these accelerated ageing conditions. 19 refs. USA
Accession no.654416 Item 206 Journal of Materials Science.Materials in Medicine 8, No.10, Oct.1997, p.631-5 CONDITIONING FLUID INFLUENCES ON THE SURFACE PROPERTIES OF SILICONE AND PU PERITONEAL CATHETERS: IMPLICATIONS FOR INFECTION Gorman S P; Jones D S; Mawhinney W M; McGovern J G; Adair C G Belfast,Queen’s University Details are given of the adherence of Staphylococcus epidermidis to PU and silicone peritoneal catheters in the presence and absence of proteinaceous conditioning film. The effects of these conditioning films on the surface properties of the biomaterials were investigated. Bacterial adherence was examined using a radiometric adherence assay. 25 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.653384 Item 207 International Polymer Processing 12, No.2, July 1997, p.174-81 DETERMINATION OF INTER-RELATIONSHIPS BETWEEN PROCESSING CONDITIONS AND PROPERTIES OF INJECTION MOULDED
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SILICONE RING USING EXPERIMENTAL DESIGN Barbaroux M; Stalet G; Regnier G; Trotignon J-P Dow Corning France SA; Ecole Nationale Superieure des Arts et Metiers The effects of injection moulding parameters on the mechanical-physical properties of a liquid silicone rubber (LSR) injection moulded ring are studied through an experimental design. The effects of the changeover point (volume or pressure driven), runner (hot or cold), hold pressure, mould temperature and injection flow rate variations are evaluated based upon the responses related to both material properties (ultimate elongation and tensile stress in a tensile test, swelling in hexane, hardness, density) and ring properties (cross sectional diameter, weight, volume). It is determined that ring density is not dependent on the parameters studied. The mould temperature appears to be a very influential parameter, especially concerning material characteristics: it affects the swelling ratio, hardness, and ultimate properties, but weight and volume are only affected when the cold runner is used. The hold pressure has an effect on both the weight and volume of the ring. The type of changeover used (volume or pressure) has no effect when a cold runner is used, but affects the weight, volume and ultimate properties of the ring, when a hot runner is used. The injection flow, rate does not affect the observed characteristics. 20 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.652454 Item 208 Biomedical Materials July 1997, p.12 SILICONE IMPLANTS ARE AT CENTRE OF FRESH CONTROVERSY This abstract describes the problems associated with assessing the long-term risks of silicone implants. The article includes information on the current controversy over possible adverse health effects of silicone breast implants and the carcinogenical potential associated with lifetime tissue exposure to various forms of silicone polymers. US,FOOD & DRUG ADMINISTRATION EUROPEAN COMMUNITY; EUROPEAN UNION; UK; USA; WESTERN EUROPE
Accession no.651091 Item 209 Polymers for Advanced Technologies 8, No.7, July 1997, p.465-70 OXYGEN-CROSSLINKED POLYSILANE: NEW CLASS OF SI-RELATED MATERIAL FOR ELECTROLUMINESCENT DEVICES Hiraoka T; Majima Y; Murai S; Nakano Y; Hayase S Toshiba Corp.
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The preparation and optical properties of the novel silicone-related material, oxygen-crosslinked polysilane, are investigated. The oxygen-crosslinked polysilane is prepared by the thermal annealing of the precursor polysilane bearing alkoxyl groups. The photoluminescence, consisting of a broad visible band at about 440 nm and a relatively sharp band at about 360 nm, is observed at room temperature. The relative intensities of the visible emission are changed during crosslinking. Visible emission is greatly affected by the steric hindrance of the alkoxyl groups of the precursor. Visible electroluminescene (EL) is also observed uniformly from the EL cell consisting of the oxygencrosslinked polysilane film sandwiched between the Al electrode and indium-tin oxide (ITO) electrode. The current densities of the EL cell increase with an increase in the oxygen-crosslinking. 15 refs. JAPAN
Accession no.648094 Item 210 Chemistry & Industry No.13, 7th July 1997, p.498 NO EVIDENCE OF SILICONE IMPLANT HEALTH RISK A new study from the American Academy of Neurology has reported that there is no evidence to show that silicone implants cause disease. The article supplies details of the report’s findings, which could shatter the hopes of thousands of women who are suing for damages over the alleged link between implants and ill health. AMERICAN ACADEMY OF NEUROLOGY; DOW CHEMICAL CORP.; DOW CORNING CORP. USA
Accession no.647598 Item 211 Patent Number: US 5589119 A 19961231 SILICONE ELASTOMER SEALS FOR MOULDED PLASTIC PARTS Hetherington R C New Southland Inc. A process is described for bonding a silicone elastomer seal to a moulded plastic part, such as an electrical connector. Prior to moulding, aromatic polyamide pellets are pretreated with an aminofunctional silicone fluid and the pretreated pellets are then moulded in the presence of moisture at a temperature sufficient to chemically graft the amino function of the silicone fluid to the aromatic carbonyl function of the aromatic polyamide and to form silanol groups within the aminofunctional silicone fluid. The moulded part is coated with an organofunctional alkoxysilane having at least one vinyl group and then heated in the presence of moisture to convert the alkoxysilane into a siloxane polymer with vinyl and silanol groups. These silanol groups then react with the silanol groups of the
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References and Abstracts
aminofunctional silicone fluid. A liquid silicone elastomer, which contains sufficient Si-H groups to react with vinyl groups contained in the siloxane polymer formed from the alkoxysilane, is applied to the coated moulded plastic part, which is then heated to form a covalent bond between vinyl groups of the siloxane polymer and Si-H groups of the elastomer, the liquid silicone elastomer forming a seal, which is bonded to the moulded plastic part. USA
Accession no.647462 Item 212 Molecular Crystals & Liquid Crystals Vols 294 & 295, 1997, p.127-32 LIGHT-EMITTING DIODES BASED ON SILICON-BACKBONE POLYMERS Suzuki H NTT Electroluminescence characteristics were measured and analysed as a function of temperature, electron injecting electrodes, and the concentration of defects at the polymethylphenylsilane-electron injecting electrode interface. Applications to polymethylphenylsilane light emitting diodes are discussed. 16 refs. JAPAN
Accession no.647206 Item 213 Polymers for Advanced Technologies 8, No.6, June 1997, p.351-4 POLYSILOXANE GEL WITH LOW CROSSLINKING DENSITY FOR MAKE-UP COSMETICS Kobayashi R; Yabe S; Nomura T Kose Corp. The mechanism whereby a crosslinked silicone having a specific crosslink density was swollen in the presence of a silicone oil having a low viscosity to form a stable gel was applied to the manufacture of cosmetic foundations. Optimum conditions that provided favourable properties and satisfactory organoleptic sensation were studied. Polymethylhydrogensiloxanes with a low crosslink density were prepared by subjecting alpha,omega-divinylpolydimethylsiloxane to addition polymerisation. The viscoelasticities of the gels formed from the resultant products and silicone oil were investigated. Based on the results, it was concluded that the most suitable product was a low crosslink density material obtained by adding alpha,omega-divinylpolydimethylsiloxane to polymethylhydrogensiloxane having an average molec.wt. of 2.5 kDa under conditions in which the concentration of dimethylpolysiloxane was 60%. This product provided an enhanced viscosity at a reduced solids content. 5 refs. JAPAN
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Item 214 Advanced Materials 9, No.9, 4th July 1997, p.741-6 STABILITY OF MOULDED POLYDIMETHYLSILOXANE MICROSTRUCTURES Delamarche E; Schmid H; Michel B; Biebuyck H IBM Corp. One aspect of the use of elastomeric materials for the formation of the stamps central to existing demonstrations of microcontact printing and micromoulding in capillaries (MIMIC) is examined: the stability of features in elastomeric stamps to the processes of their formation and subsequent application. The key function of elastomeric stamps is to provide a pattern of relief on the surface of a flexible solid used to transfer or mould the shape of material in its image. Fabrication of a stamp requires its replication from a master. Liquid polydimethylsiloxane (PDMS) is poured on top of the master, which is formed in photoresist, directly in silicon, or in some other material. The lowenergy siloxane fluid fills the crevices of the master, forming a negative replica of the surface. Further crosslinking of the siloxane by light-initiated or metalcatalysed reaction results in an elastomeric solid that preserves on its surface - in the best cases - an accurate record of the topology after its separation from the master. The pattern of reliefs in the surface of the stamp is then useful in transferring inks to a substrate by contact between raised regions of the stamp and the surface of the substrate. Alternatively, these reliefs act as moulds or conduits for solids or liquids and thus as a direct template to form patterns in these materials. 16 refs. SWITZERLAND; WESTERN EUROPE
Accession no.645230 Item 215 NRC ’96. Conference proceedings. Helsinki, 23rd-24th May,1996, paper 9. 8 SILICONE RUBBER IN SPECIAL APPLICATIONS Dietl S Wacker-Chemie GmbH (Finnish Association for Rubber Technology; Nordic Council of Rubber Technology) Silicone rubber is well-known as a special elastomer for the solution of problems in individual applications. Its unique combination of outstanding properties leads to hundreds of cases where silicone rubber is the only choice. On account of its versatility, silicone rubber may be tailored to the demand of special tasks. The lecture covers well-known applications as well as fascinating new ones. Silicone rubbers can be used in a number of applications, including high-temperature, low-temperature, electrical, flame retardant, health care, food-contact, baby-care, household, construction and automotive applications. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
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Item 216 Journal of Biomedical Materials Research 35, No.4, 15th June 1997, p.505-11 THEORETICAL ANALYSIS OF HYDROLYSIS OF POLYDIMETHYLSILOXANE(PDMS) West J K Florida,University The hydrolysis of PDMS, commonly used in breast implants, was theoretically modelled using a semiempirical quantum mechanical model (AM1). The activation barrier for removing a methanol monomer was found to be +82 Kcal/mol, while the removal of a methane monomer was +41 Kcal/mol. Using the same AM1 method, hydrolysis of the -Si-O-Si- bond was also modelled for pentasilicic acid and 1,1,3,3tetramethyldisiloxane-1,3-diol. The barrier to the removal of a silicon-containing tetrahedron for both studies was found to be +27 Kcal/mol. This was approximately one and a half times smaller than the energy of that needed to remove a methyl group. The pentacoordinated silicon-activated transition state for hydrolysis of PDMS could provide an energetically favourable pathway for development of a surface that would enhance chemisorption of charged protein molecules and such a pathway map could show up in NMR studies of the hydrolysis of PDMS. 28 refs. USA
Accession no.640133 Item 217 151st ACS Rubber Division Meeting, Spring 1997, Conference Preprints. Anaheim, Ca., 6th-9th May 1997, Paper 88, pp.24. 012 NMR OF TISSUES EXPOSED TO POLYSILOXANE GELS Garrido L Massachusetts General Hospital; Harvard Medical School (ACS,Rubber Div.) The migration of polysiloxanes from polysiloxane gel filled breast implants to local and distant sites in living systems was studied by NMR spectroscopy. Tissues from animals and humans exposed to the implants were studied in-vivo using proton NMR localised spectroscopy and invitro with proton and silicon-29 magic angle spinning NMR spectroscopy. The results showed that free polysiloxanes present in the implants migrated to surrounding tissues and distant organs such as the liver. In addition, silicon-29 NMR spectra of metabolically active tissues (liver) showed the presence of chemically unchanged polysiloxanes and other silicon-containing compounds (silica), suggesting that these polymers were biodegradable. 45 refs. USA
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Item 218 151st ACS Rubber Division Meeting, Spring 1997, Conference Preprints. Anaheim, Ca., 6th-9th May 1997, Paper 74, pp.2. 012 ADVANTAGES OF SILICONE ELASTOMERS IN THE CONSTRUCTION OF ROLLERS Lapsley T; Dickson S American Silicones (ACS,Rubber Div.) An examination is made of the range of properties obtainable in rollers covered with silicone rubbers. USA
Accession no.639054 Item 219 151st ACS Rubber Division Meeting, Spring 1997, Conference Preprints. Anaheim, Ca., 6th-9th May 1997, Paper 62, pp.8. 012 SILICONE RUBBER APPLICATIONS: WHY SILICONES ARE USED Finney D; Papa J General Electric Co.,Silicone Products Div. (ACS,Rubber Div.) Uses of silicone rubbers in automotive and aerospace applications, high voltage insulators and business machine components are reviewed, and the reasons for selecting silicone rubbers for such applications are discussed. 3 refs. USA
Accession no.639044 Item 220 Antec 97. Volume I. Conference proceedings. Toronto, 27th April-2nd May 1997, p.308-14. 012 POLYFLOW: TREATISE ON INVERSE DIE/ MANDREL DESIGN FOR HIGH CONSISTENCY SILICONE ELASTOMER Andrejewski D A Dow Corning Corp. (SPE) To date, manufacturing experiences low production yields when extruding complex cross-sections with high consistency silicone rubber. In the extrusion process, shear is imparted and introduced to the material, causing both shear thinning and elastic effects which make the die/ mandrel design uncertain. Computational Fluid Dynamic methods (Polyflow) were utilised to model the flow characteristics of the material through the die/mandrel to determine their proper shape with respect to the required extrudate. Non-linear viscoelastic constitutive models correlating rheology with the actual flow dynamics were utilised in the software to achieve this end. The die/ mandrel design developed through the modelling techniques demonstrated their invaluable need by boosting production rates as high as 167%, and decreasing waste and set-up time 18-fold respectively. Finally, the
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References and Abstracts
process developed should be utilised to improve existing and future designs where complex profiles cause long setup times and high scrap rates. 5 refs. USA
Accession no.636428 Item 221 Biomaterials 18, No.8, 1997, p.635-41 PHYSICOCHEMICAL PROPERTIES OF A RIFAMPICIN-RELEASING POLYDIMETHYLSILOXANE SHUNT Schierholz J M Cologne,University Results of studies of the above are presented and discussed, particular attention being paid to the cohesion energy (solubility parameter) of the polydimethylsiloxane network and rifampsin, controlled delivery of rifampsin from the silicone network, mechanical properties of the conventional and modified silicone shunt, differential calorimetric determinations of drug, polymer and the drug-polymer system, and SEM of the polymer and the polymer-rifampsin system. Rifampsin is a competitive inhibitor of bacterial RNA polymerase. 30 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.634645 Item 222 China Rubber Industry 44, No.4, April 1997, p.233-6 Chinese STUDY ON RUBBER COMPOUNDS OF HIGH VOLTAGE CAP AND WEDGE FOR TELEVISION SET Wu Shishan; Dou Qiang; Liu Gang; Ma Liming Nanjing,Institute of Chemical Technology; Nanjing Jiangpu Dougang Plastics Factory Silicone rubber compounds of high voltage cap and wedge for colour television sets were developed. The effect of flame retardant and filler on the physical properties, flame retardance and electrical properties was investigated. The results showed that good flame retardance was obtained with antimony oxide/DBDPO blend flame retardant system, 3-4 phr of silica being adequate. The formulation developed included silicone rubber (151 mix type) 100 parts, 2,5-dimethyl-2,5-bis(tert-peroxy)hexane 1 part, antimony oxide 2 parts, DBDPO 4 parts, silica 4 and 3 parts, respectively, for high voltage cap compound and wedge compound. 3 refs. CHINA
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26, No.14, 24th Feb.1997, p.19 MOHAWK TURNING OUT RUBBER COMPONENTS Whitford M Mohawk Plastics Inc. is a manufacturer of thermoplastic and thermoplastic elastomer gasket carriers for car makers. Details are given of its expansion plans which involve the adding of liquid silicone injection moulding machines for engine gasket construction. The company is currently increasing capacity for carriers at its Marine City factory and plans to double floor space there. MOHAWK PLASTICS INC. USA
Accession no.631852 Item 224 Plastics and Rubber Asia 12, No.69, March 1997, p.32 LIQUID SILICONE DEMONSTRATES SAVING POWER Advantages of the use of liquid silicone rubber Silopren LSR were demonstrated at Aseanplas, by Bayer. Using an adapted Engel 90 tonnes clamping force injection moulding machine, a cycle time of 22 seconds was achieved to produce injection moulded parts. LSR is reported to be popular in Asia, with applications in baby bottle teats and keyboards, and Bayer hopes that the power industry will use it in the future to replace porcelain high voltage insulators. BAYER AG Accession no.631813 Item 225 Analytical Chemistry 69, No.7, 1st April 1997, p.1267-72 DETECTION AND CHARACTERIZATION OF POLYDIMETHYLSILOXANES IN BIOLOGICAL TISSUES BY GAS CHROMATOGRAPHY(GC)/ ATOMIC EMISSION DETECTION(AED) AND GC/MASS SPECTROMETRY(MS) Kala S V; Lykissa E D; Lebovitz R M Baylor College of Medicine A sensitive method was developed for detection, characterisation and quantification of low molec.wt. silicones using GC/AED and G C/MS. Using this approach, twelve distinct silicon-containing peaks were detected in polydimethylsiloxane oil by GC/AED, and GC/MS analysis was used to identify some of the abundant peaks by MS spectral matching. The described methodology was shown to have the potential to allow the measurement of less than 1 micro g of silicone/g of biological tissue. 8 refs. USA
Item 223 Rubber and Plastics News
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Item 226 European Rubber Journal 179, No.4, April 1997, p.27-8 SILICONES STILL A GROWING AREA White L
Item 229 British Plastics and Rubber March 1997, p.21-2 PROCESSING AS A LIQUID CUTS THE COST OF SILICONE RUBBER
The major French silicone sealant supplier, Rhone Poulenc, says is is focusing on innovation and new products. It is particularly optimistic about prospects for its new generation of water-based silicone sealants. Dow Corning estimates growth in silicone sealants as averaging about 5-6%, with regional variations. The sealants business is heavily dependent on the health of the construction sector. Europe and Japan, for example, are experiencing poorer conditions than others for sealant sales.
Liquid silicone rubber is a transparent rubber material with degrees of hardness between 20 and 90 Shore A, which crosslinks rapidly when mould temperature reaches about 200C. The 2KM Silco-Mix metering system from Prodef Engineers permits both material components to be dosed directly from their original drums. Demag Ergotech 25 and 35 tonne injection moulding machines with a specially designed screw and barrel are now available for LSR moulding. Processing requirements are discussed. PRODEF ENGINEERS LTD.; MANNESMANN DEMAG; MIR SPA; SILICONE ALTIMEX LTD.
WESTERN EUROPE-GENERAL
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Item 227 European Plastics News 24, No.4, April 1997, p.24-5 FLEXIBLE SOLUTIONS Anscombe N With the correct processing equipment, liquid silicone rubbers can be easily moulded into a huge variety of products. Standard injection moulding machines need to be modified before they can be used for LSR processing. This is done with relative ease and involves changes to the dosing equipment, barrel, screw and mould nozzles. MANNESMANN DEMAG EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.630218 Item 228 Patent Number: US 5539020 A 19960723 METHOD AND DEVICE FOR CUSHIONING LIMBS Bracken R L; Winn R A; Riley N L Schering-Plough HealthCare Products Inc.
Accession no.628609 Item 230 Patent Number: US 5531923 A 19960702 TWIN-SCREW EXTRUSION OF SILICONE DOUGHS SUITED FOR SIH/SIVI RTV COMPOSITIONS Le Blanc L; Pagliari R Rhone-Poulenc Chimie Silicone doughs suitable for incorporation into diorganopolysiloxane compositions crosslinkable into elastomeric state are rapidly and conveniently formulated by continuously and simultaneously individually introducing along the longitudinal axis of a twin screw extruder, via a plurality of longitudinally spaced discrete inlet entries, and twin screw extruding (a) a polydiorganosiloxane oil having a viscosity at 25C of less than 500000 mPa.s and containing at least two given functional groups per molecule, (b) water, (c) silica, and (d) a polysilazane which is liquid under normal conditions of temperature and pressure. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
A soft, tacky polysiloxane elastomer, which has a tackiness of 10 to 450 grams, as determined by a polyken probe tack tester, or 0 to 10 cm, as determined by a rolling ball tack tester, and a tensile strength of 0.14 to 5.52 mega Pascals (20 to 800 pounds/sq.in.), a minimum elongation of 250 to 1100% and a tear strength of 0.88 to 35.2 kN/m (5 to 200 pounds/sq.in.) is disclosed. It can be made into various cushioning devices with or without a topcover, including an arch support pad, a metatarsal pad, a heel cushion, sheet padding, a full-length insole, a three quarter length insole, a half insole, a toe-crest pad, a heel liner, an elbow pad, a corn pad, a callus pad, a blister pad, a bunion pad or a toe pad.
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Details are given of the technique of replica moulding for manufacturing nanostructures with emphasis given
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Item 231 Advanced Materials 9, No.2, Feb.1997, p.147-9 REPLICA MOULDING USING POLYMERIC MATERIALS: PRACTICAL STEP TOWARD NANOMANUFACTURING Xia Y; McClelland J J; Gupta R; Qin D; Zhao X-M; Sohn L L; Celotta R J; Whitesides G M Harvard University; US,National Inst.of Standards & Technology; Princeton,University
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References and Abstracts
to the use of elastomeric masters. Data are given for PDMS, PMMA, and PU. 13 refs. USA
Accession no.626453 Item 232 Patent Number: US 5516838 A 19960514 FLAME RETARDANT SILICONE COMPOSITIONS Hironao Fujiki; Masayuki Ikeno; Hiroyasu Hara; Kasuyasu Satoh Shin-Etsu Chemical Co.Ltd. To a silicone composition comprising (A) an organopolysiloxane having at least two alkenyl groups in a molecule, (B) an organohydrogenpolysiloxane having at least two hydrogen atoms each directly attached to a silicon atom in a molecule, and (C) a platinum catalyst, (D) a compound having a phenyl group and a secondary or tertiary amino group directly attached thereto is added to render the composition flame retardant. The composition cures into a transparent product having improved flame retardancy meeting the UL standard and is suitable for use in the protection of electronic parts like IC’s and hybrid IC’s. JAPAN
Accession no.625227 Item 233 Patent Number: US 5525427 A 19960611 ABRASION RESISTANT SILICONE WEATHERSTRIP COATING Griswold R M; Lin S B General Electric Co. A water reducible weatherstrip coating comprises a two or three component system comprising a silicone emulsion base, a bath-life extender, and a crosslinking composition. USA
Accession no.624955 Item 234 Injection Moulding International 1, No.1, Nov./Dec.1996, p.36 INTELLIGENT REDESIGN CUTS COST IN HALF Neilley R A computer keyboard mat, situated under the keys, flexes to transmit the signal then returns the key to its start position. Traditionally, keyboard mats have been compression moulded in NR. Starlim GmbH, a liquid injection moulder of liquid silicone rubber, has redesigned the part, cutting the finished part weight by more than half and significantly improving the mat’s performance and durability. The new design is a pattern of domes and thin connecting strips.
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STARLIM GMBH EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.624824 Item 235 Plastics and Rubber Weekly No.1676, 7th March 1997, p.20 SEMINAR SELLS LIM GE Silicone and Mannesmann Demag Hamilton recently joined forces to introduce thermoplastic moulders to the benefits of liquid injection moulding of silicone elastomers. From a cost point of view alone, switching from processing thermoplastics to silicone LIM is a smaller hurdle than from conventional heat cure elastomers to LIM. Production of an automotive spark plug connector was used to demonstrate that silicone LIM can be carried out on relatively lightly modified moulding equipment. GE SILICONES; MANNESMANN DEMAG HAMILTON LTD. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.624534 Item 236 Journal of Biomedical Materials Research 34, No.2, Feb.1997, p.201-10 ADHESION TO SILICONE RUBBER OF YEASTS AND BACTERIA ISOLATED FROM VOICE PROSTHESES: INFLUENCE OF SALIVARY CONDITIONING FILMS Busscher H J; Geertsema-Doornbusch G I; van der Mei HC Groningen,University Adhesion of two streptococcal, staphylococcal, Candida albicans and Candida tropicalis strains, isolated from explanted voice prostheses was investigated to silicone rubber with and without a salivary conditioning film in a parallel-plate flow chamber. Within each microbial pair of one species, the strain with the most negative zeta potential adhered most slowly to negatively charged silicone rubber. No other clear relationships were obvious between adhesion to silicone rubber and microbial zeta potentials or cell-surface hydrophobicities, as by water contact angles. 37 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; NETHERLANDS; WESTERN EUROPE
Accession no.622299 Item 237 Plast’ 21 No.47, Nov.1995, p.85-6 Spanish PRODUCTION OF PLASTICS AND METAL PROTOTYPES BY VACUUM CASTING
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Ferrandiz S AIJU An account is given of techniques used by AIJU of Spain for the vacuum casting of plastics and metal prototypes for the toy industry using silicone rubber moulds. EUROPEAN COMMUNITY; EUROPEAN UNION; SPAIN; WESTERN EUROPE
Accession no.621102 Item 238 Materie Plastiche ed Elastomeri No.9, Sept.1995, p.524-7 Italian YEAR OF EXTRUSION A survey is made of developments by GE Plastics in engineering plastics grades for extrusion and injection moulding. Uses of these materials in electrical, telecommunications, lighting and automotive applications and domestic appliances are examined. Details are also given of silicone polymer coatings, liquid silicone rubbers and silicone rubber gels developed by GE Silicones. GE PLASTICS; DELPHI INTERIOR & LIGHTING SYSTEMS; GE SILICONES USA
Accession no.621090 Item 239 Biomaterials 17, No.23, 1996, p.2265-72 TISSUE RESPONSE TO COMMERCIAL SILICONE AND POLYURETHANE ELASTOMERS AFTER DIFFERENT STERILISATION PROCEDURES Zhang Y Z; Bjursten L M; Freij-Larsson C; Kober M; Wesslen B Lund,University A silicone and a polyurethane elastomer were studied with regard to correlations between the chemical and physical compositions of the polymer surfaces and the biological response on implantation. Test specimens of the materials were manufactured according to standard procedures. The specimens were implanted into rats for 10 and 90 days. Before implantation, the polymers were sterilised by beta irradiation, ethylene oxide sterilisation and steam sterilisation. The polymers were characterised before and after implantation with respect to chemical composition and morphology of the surfaces. After implantation the biological response was evaluated by counting numbers of macrophages, giant cells, fibroblasts and other cells present at the surfaces. The thickness of the fibrous capsule surrounding the test specimens was measured at the thickest and thinnest parts. 17 refs. SCANDINAVIA; SWEDEN; WESTERN EUROPE
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Item 240 Degradation and Stabilization of Materials. Applied Polymer Symposium proceedings. Alexandria, 26th-30th Sept.1992, p.231-42. 012 STUDY OF SOME PROPERTIES OF ALGINATE AND SILICONE RUBBER BASE IMPRESSIONS AFTER IMMERSION DISINFECTION Taymour N M; El-Shabrawi Alexandria,University Edited by: Kandil S H (Alexandria,University) Applied Polymer Symposium 55 Dental impressions of an engraved metal die were made with alginate and silicone rubber base impression materials. After separation from the metal die, all impressions were soaked (before pouring with Type IV gypsum) into a variety of test disinfectants via a 30-min immersion time. Following immersion disinfection, the linear dimensions of each stone cast (both intra-arch and cross-arch dimensions) were measured. Surface hardness characteristics of all the resultant casts were also examined. Analysis of the results showed that all the broad-spectrum disinfectant agents used offered effective antimicrobial activity without distorting the impressions. There was no significant linear dimensional change or any alteration in the surface hardness characteristics of all the examined stone casts. 19 refs. EGYPT
Accession no.611280 Item 241 Rubber Technology International 1996, p.109-11 PLATINUM CURED SILICONE COMPOUNDS Sullivan G Dow Corning STI Recent advances in platinum-catalysed silicone compounds have produced high performance liquid silicone rubber materials and rapid curing high consistency rubber formulations. Both are helping moulders to reduce fabricating costs and increase processing speeds over conventional peroxide-cured silicones. This comprehensive article supplies full details. USA
Accession no.610806 Item 242 Rubber and Plastics News 26, No.5, 7th Oct.1996, p.28 ACTIVISTS ASK FDA TO RETHINK IMPLANT BAN Moore M Two members of Congress are reported to have joined anti-cancer activists in Washington to call on the Food and Drug Administration to reconsider its moratorium on
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References and Abstracts
silicone gel breast implant use. A petition calls on the agency to ease restrictions on silicone implants for breast cancer patients. It relies on the body of sound scientific evidence that has been produced since the FDA commissioner severely limited access to these medical devices four years ago. This evidence strongly suggests that there is no causal link between silicone-gel implants and systemic connective tissue diseases or classic autoimmune symptoms. Silicone breast implants are currently available only to patients involved in the FDA clinical trials to monitor the effects of silicone on women. Details are given. USA
Accession no.610082 Item 243 Injection Molding 4, No.9, Sept.1996, p.98/104 FOR LSR, HIGH TECHNOLOGY OUTWITS LOW LABOUR COSTS Neilley R An Austrian company, Starlim GmbH, has won back from Asia a keyboard contact mat production job, which was sourced from Asia due to its low labour costs, since the compression moulded natural rubber mats required postmould trimming and involved much handling. Starlim uses liquid injection moulding of silicone rubber, sophisticated moulds, and an injection system to produce the product at half the cost, whilst improving performance and durability. Details are given of the production by Starlim, and the redesign of the mat into a pattern of domes and connecting strips. STARLIM GMBH ASIA; AUSTRIA; WESTERN EUROPE
Accession no.608155 Item 244 Advanced Packaging 5, No.5, Sept/Oct.1996, p.30/2 FINDING A CURE Vanwert B; Wilson S W; Hanlon A Dow Corning Corp. Electronic applications are reported to demand that adhesive products possess a number of properties in addition to good adhesion and compatibility with substrate materials. Most adhesives used in a production environment are heat cured, both for processing speed and ultimate physical properties. Flexibility is also necessary to prevent damage during temperature cycling, even if the assemblies are not subjected to extreme heat or cold. Finally, the ability to maintain physical properties in the presence of moisture, contaminants and varying temperatures is imperative for many applications. Aspects of silicone adhesives in electronic applications described include application requirements, physical properties, processing requirements, cure mechanisms and testing.
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Accession no.607356 Item 245 Chemistry of Materials 8, No.8, Aug.1996, p.1735-8 NANOCOMPOSITES PREPARED BY THREADING POLYMER CHAINS THROUGH ZEOLITES, MESOPOROUS SILICA, OR SILICA NANOTUBES Frisch H L; Mark J E New York,State University; Cincinnati,University A brief review is given of preliminary attempts to prepare nanocomposites in which PDMS chains thread through the cavities or channels of several types of inorganic materials. Emphasis is given to the use of zeolites, a mesoporous hexagonal form of silica, and silica nanotubes. The effects of the constraining geometry on the properties of the chains, particularly their Tg were determined. 91 refs. USA
Accession no.603765 Item 246 Antec ’96. Vol.I. Conference Proceedings. Indianapolis, 5th-10th May 1996, p.381-5. 012 TWIN-SCREW EXTRUSION PROCESSING OF FILLED POLYMERS Lawal A; Railkar S; Yaras P; Kalyon D M Stevens Institute of Technology (SPE) Results are presented of an integrated study of the extrusion behaviour of a viscoplastic polydimethyl siloxane suspension filled with hollow glass spheres. The rheological properties of the suspension, including the Navier wall slip condition, were characterised by multiple viscometric flows. The pressure and temperature history in the co-rotating twin-screw extrusion process was simulated using finite element analysis and compared with experimental data collected with a well instrumented 50.8 mm twin-screw extruder. The model results agreed well with the experimental data and provided a detailed understanding of the thermomechanical history experienced by the suspension during twin-screw extrusion. 43 refs. USA
Accession no.602941 Item 247 Biomaterials 17, No.16, 1996, p.1627-30 DYNAMIC MECHANICAL THERMAL ANALYSIS OF DENTURE SOFT LINING MATERIALS Waters M; Jagger R; Williams K; Jerolimov V Wales,University; Zagreb,University
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References and Abstracts
Details are given of the characterisation of the deformation properties of a range of long-term denture soft lining materials using dynamic mechanical thermal analysis. Specimens were subjected to sinusoidal shear deformation to simulate the type and rate of deformation soft lining materials would experience clinically. Data are given for various acrylic resins and silicone elastomers. 7 refs. CROATIA; EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.602615 Item 248 Industria della Gomma 39, No.5, May 1995, p.47-8 Italian LIQUID SILICONE RUBBERS FOR INJECTION MOULDING Processing conditions and machinery used in the injection moulding of liquid silicone rubbers are described. Types of products which can be manufactured by this process are examined, and causes of moulding faults are briefly reviewed. GE SILICONES
Item 251 Patent Number: US 5459167 A 19951017 PROCESS FOR PRODUCING A FORMED SILICONE FOAM BY INJECTION MOULDING Giesen F J Fuller H.B.,Licensing & Financing Inc. To manufacture high quality, fine pored silicone foam parts by the injection moulding process, two reaction components A and B are used. They both contain a silicone polymer and fumed silica. The component A also contains a complexed organo-platinum catalyst and a small portion of water, whereas the other component B contains as a crosslinker polydimethyl hydrogen siloxane. At least one of the two components A and B of the mixture is pressurised with a gas, preferably air or nitrogen, in a pressure container so that the gas is dissolved into the component(s). The components A and B are mixed in the pressure process, injected into an injection mould, and heated so that the foaming process forms the silicone foam part. USA
Accession no.596618
USA
Accession no.598421 Item 249 Industria della Gomma 39, No.5, May 1995, p.45-6 Italian MARGUM 1715U: A SILICONE RUBBER FOR WIRE AND CABLE EXTRUSION Cabrini G Dow Corning STI Data are presented for the mechanical and electrical properties and flammability characteristics of Margum 1715U, a silicone rubber compound developed by Dow Corning STI for applications in wire and cable extrusion. EUROPEAN COMMUNITY; EUROPEAN UNION; ITALY; WESTERN EUROPE
Accession no.598420 Item 250 Industria della Gomma 39, No.5, May 1995, p.42-5 Italian PROPERTIES AND SELECTION OF SILICONE RUBBERS Steinberger H Bayer AG The structure, properties, vulcanisation and processing of silicone rubbers are examined. Properties and applications of Silopren silicone rubbers produced by Bayer are described. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.598419
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Item 252 Journal of Applied Polymer Science 61, No.4, 25th July, 1996, p.703-13 COLLAPSIBLE-TUBE PULSATION GENERATOR FOR CROSSFLOW MICROFILTRATION: FATIGUE TESTING OF SILICONE RUBBER TUBES Hadzismajlovic D E; Bertram C D New South Wales,University Fatigue tests were performed on 18 silicone rubber tubes operating as the active element of a crossflow pulsation generator. 22 refs. AUSTRALIA
Accession no.596012 Item 253 Analyst 121, No.6, June 1996, p.53R-63R SILICONES AND THEIR DETERMINATION IN BIOLOGICAL MATRICES: A REVIEW Cavic-Vlasak B A; Thompson M; Smith D C Toronto,University A review of the literature on silicones and their determination in biological matrices is presented. The following topics are covered: properties and applications of silicones; biochemistry of elemental silicon and silicones; general approach to the determination of trace amounts of silicones in biological materials; survey of methods used for non-specific and silicon-specific microstructural determination of silicones in tissues (microanalysis); silicone-specific (elemental) techniques for the detection of silicones in biological materials;
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References and Abstracts
survey of silicone-specific techniques (IR, FTIR, Raman, NMR spectroscopies, gas chromatography(GC) and GCmass spectrometry methods); and problem of speciation of silicon and identification of silicone biotransformation products in biological samples. 124 refs. CANADA
Accession no.595316 Item 254 Patent Number: US 5472994 A 19951205 MICROWAVE-HEATABLE EXERCISE PUTTY Micallef A M; Gibbon R M JMK International Inc. A microwaveable exercise putty includes a borosiloxane or stannosiloxane reaction product. The resulting reaction product is mixed with a second polysiloxane, an internal lubricant such as a monounsaturated fatty acid, and a particulate material which creates heating upon subjection to microwave energy. Precipitated silica is a particularly preferred particulate material. The exercise putty may be manipulated by patients, and at the same time is capable of delivering heat to the body part undergoing the manipulation. USA
Accession no.594354 Item 255 IRSG 36th International Rubber Forum 1995: Factors Affecting the Development of the Rubber Industry in the Pacific Rim. Conference Proceedings. Tokyo, 27th Feb.-3rd March 1995, p.143-158 SILICONE ELASTOMERS: THEIR PRESENT APPLICATIONS AND FUTURE POTENTIAL Tanimura M Dow Corning Toray Silicone Co.Ltd. This paper discusses silicone markets, major suppliers, silicone as an elastomer, silicone rubber applications, trends in technology and the future outlook. In the US, the automotive sector is the most important for silicone rubbers and accounts for 40% of the total market. In Japan, 55% of the total market is accounted for by the electrical/ electronic sector. In the Pacific region, excluding Japan, 68% goes into electrical/electronic manufacturing. New and emerging applications include automotive airbag coating, electrical insulators and copier/printer wells. JAPAN
Accession no.593330 Item 256 Patent Number: EP 718369 A1 19960626 METHOD OF REDUCING HOT HYDROCARBON OIL SWELL OF FILLED SILICONE SEALANT GASKETS Lower L D Dow Corning Corp.
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The gaskets are made from a room temperature vulcanisable silicone sealant composition containing a hydroxyl endblocked polydimethylsiloxane, calcium carbonate or a combination of calcium carbonate and reinforcing silica filler, a specifically selected ketoximosilane crosslinker combination, such as vinyltriketoximosilane and methyltriketoximosilane and a catalyst. They cure rapidly enough to be used on an automated production line for formed-in-place gaskets. USA
Accession no.592982 Item 257 British Engel Elast Symposium 1995. Symposium Proceedings. Warwick, 21st-22nd June 1995, paper 6, pp.16. 831 LIQUID SILICONE RUBBER - PROCESSING, APPLICATIONS AND DEVELOPMENTS Naumann T Bayer AG (Engel Vertriebsges mbH) This paper presents information in some detail on processing properties and injection moulding applications of Silopren LSR liquid silicone rubber from Bayer. Applications listed include electronics, electrical appliances, automotive products, medical and textile applications. Newly developed Silopren LSR products, mould technology and product design are outlined. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.590902 Item 258 Polymer Science Series A 38, No.3, March 1996, p.225-31 THERMALLY STABLE ELASTOMERS: IN RETROSPECT OF TWO DECADES Sokolov S V; Kolokol’tseva I G Russia,State Research Institute of Synthetic Rubber State-of-the-art advances that marked the past two decades in the synthesis and application of thermally stable siloxane and fluorocarbon elastomers are reviewed. The main trend consists in changing the priorities from aerospace applications to automotive and other consumer goods applications, which determine the new requirements for the properties of thermally stable elastomers. 12 refs. RUSSIA
Accession no.590686 Item 259 Rubber and Plastics News 25, No.18, 25th March 1996, p.15 STUDY STIRS BREAST IMPLANT CONTROVERSY
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References and Abstracts
Moore M It is reported that pro- and anti-breast implant forces are drawing opposite conclusions from a new epidemiology study, the results of which were recently published by researchers at the Harvard University-affiliated Brigham & Women’s Hospital in Boston. Former silicone implant manufacturers claim that the study shows that there is no major risk of disease among women with breast implants. Opponents of silicone gel breast implants, however, say that the report invalidates their position. Details are given. HARVARD UNIVERSITY; BOSTON,BRIGHAM & WOMEN’S HOSPITAL USA
Accession no.589896 Item 260 Patent Number: EP 699512 A1 19960306 LIQUID SILICONE RUBBER INJECTION MOULDING MACHINE Grenda D Whitaker Corp. A distribution member for the above machine comprises a channel distribution network for feeding liquid silicone rubber to a mould die. The silicone rubber is vulcanised by heating the mould die to around 120C and heat must be prevented from flowing into feed pipes and nozzles of the distribution network to ensure that the injection fluid does not vulcanise within the feed channels. Plastic heat insulating feed pipes and nozzles are provided to prevent overheating of the fluid in the feed channel. The liquid silicone rubber does not bond to these pipes and nozzles. The feed pipes can be provided with a reflective outer surface and separated from plate members by an air gap to further reduce heat transfer. Advantages of the machine are reduction in machine cost, easy and cheap replacement of nozzles and feed pipes and increased reliability.
Item 262 Medical Device Technology 7, No.2, March 1996, p.22/8 PURCHASING SILICONE Pryce T SF Medical Ltd. Differences in medical grade and food contact grade silicone polymers are discussed with reference to CE marking. Medical device manufacturers need to be able to document that they employ the correct materials and components for a particular application, and to demonstrate that their suppliers possess the necessary product range, technical expertise and quality procedures necessary to assure product integrity. An explanation is offered of the inspection and testing terms relating to material specification and testing of silicone polymers. 3 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.584577 Item 263 Revista de Plasticos Modernos 68, No.462, Dec.1994, p.568-71 Spanish LIQUID SILICONE RUBBER: A HIGH PERFORMANCE MATERIAL OF THE FUTURE Schulze M Bayer AG The processing and applications of Bayer’s Silopren LSR liquid silicone rubbers are examined. The environmental advantages of these materials and quality control procedures used in their manufacture are described. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.583103
USA
Accession no.589497 Item 261 IRC ’95 Kobe International Rubber Conference. Conference proceedings. Kobe, 23rd-27th Oct.1995, p.91-4. 012 ADHESION OF ADDITION CURE SILICONES TO THERMOPLASTIC Fujiki H; Shudo S Shin-Etsu Chemical Co.Ltd. (Japan,Society of Rubber Industry) A new addition curing silicone rubber having selective bonding to polycarbonate, PBTP, etc. without adhering to the mould (metal) in thermoplastics insert molding and co-injection moulding is described. JAPAN
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Item 264 Trends in Polymer Science 4, No.2, Feb.1996, p.52-9 SILICONE HYDROGELS FOR CONTACT LENS APPLICATION Kuenzler J F Bausch & Lomb Inc. The synthetic and formulation approaches that have been pursued in the design of silicone hydrogels for use in extended wear contact lenses are reviewed. The synthesis of hydrophilic block and graft siloxanes and the use of these hydrophilic silicones in the preparation of hydrogel formulations are shown to have led to the development of transparent, wettable and low-modulus materials possessing extremely high levels of oxygen permeability. 23 refs. USA
Accession no.582511
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References and Abstracts
Item 265 Medical Plastics Industry at the Dawn of the 21st Century. Retec proceedings. Rosemont, Il., 25th-26th Oct. 1994, p.133-68 6S DESIGN OF AN INJECTION MOULDED STRUCTURAL SPINE SUBASSEMBLY FOR INTRACOCHLEAR STIMULATING ELECTRODES: THE BASIS OF LOW COST AUTOMATED ASSEMBLY Bruszewski W; Rebscher S; Heilmann M; Merzenich M California,University (SPE; SPI) Details are given of the design and manufacture of a multichannel intracochlear stimulating electrode that can be assembled by electronic pick and place robots. A subassembly incorporating stimulating contacts and a 16channel conductor array was injection moulded from silicone rubber. Other polymers analysed were polyether imide, PP, polysulphone, and polyimide. 15 refs. USA
Accession no.582186 Item 266 Journal of Biomedical Materials Research 30, No.3, March 1996, p.305-12 PILLARED-SURFACE MICROSTRUCTURE AND SOFT-TISSUE IMPLANTS: EFFECT OF IMPLANT SITE AND FIXATION Picha G J; Drake R F Baxter Healthcare Corp. Details are given of the effect of microtissue anatomy and silicone rubber implant site on fibrosis and blood vessel approximation. The effect of implant fixation using sutures was also examined. 5 refs. USA
Accession no.582162 Item 267 Macromolecular Chemistry & Physics 197, No.2, Feb.1996, p.677-86 NOVEL SILICONES FOR TRANSDERMAL THERAPEUTIC SYSTEM. VI. PREPARATION OF OLIGODIMETHYLSILOXANE CONTAINING PYRROLIDONE MOIETY AS A TERMINAL GROUP AND ITS ENHANCING EFFECT ON TRANSDERMAL DRUG PENETRATION Aoyagi T; Tadenuma R; Nagase Y Sagami Chemical Research Center Oligodimethylsiloxanes containing a pyrrolidone moiety at one chain end were prepared to develop a silicone-based transdermal penetration enhancer. The enhancing activity of drug penetration was evaluated by in vitro experiments using a two-chamber diffusion
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cell. Indomethacin and antipyrine were used as model drugs. 15 refs. JAPAN
Accession no.580996 Item 268 Journal of Biomedical Materials Research 30, No.2, Feb.1996, p.245-50 CONTRIBUTION OF VASCULAR CATHETER MATERIAL TO THE PATHOGENESIS OF INFECTION: DEPLETION OF COMPLEMENT BY SILICONE ELASTOMER IN VITRO Marosok R; Washburn R; Indorf A; Solomon D; Sherertz R Lentini Medical Center; Wake Forest,University; Akron Infectious Diseases Inc.; Becton Dickinson Pharmaceutical Systems A functional complement opsonisation assay and radioimmunoassays were used to compare the relative abilities of silicone, PU and PVC to activate complement. Serum incubated in silicone catheters for 24 h had less than 30% of the opsonising ability of fresh serum while 78% or more of the opsonising ability remained with serum incubated in PU or PVC catheters. Measurement of C3a des Arg, C4a des Arg, C5a des Arg and SC5b-9 demonstrated that the loss of opsonising ability was due to 10-fold greater alternate pathway complement activation by silicone than by PU or PVC. This finding suggested that excessive complement activation by silicone could explain the greater inflammation seen around silicone catheters in vivo and might also play a role in silicone’s creating a greater risk of infection. 47 refs. USA
Accession no.580659 Item 269 148th ACS Rubber Division Meeting. Fall 1995. Conference Preprints. Cleveland, Oh., 17th-20th Oct.1995, Paper 86, pp.12. 012 ADVANCES IN SILICONE RUBBER ENGINE GASKET SEALING Fiedler L D; Hebda T J; Kucinski E M; Lee M H; Zawadzke J K Dow Corning Corp.; Dow Corning STI (ACS,Rubber Div.) An account is given of tests undertaken by Dow Corning in the development of silicone rubber compounds for use in automotive engine gaskets, with particular reference to the optimisation of compression set resistance, compression stress relaxation properties and performance in hot oils. USA
Accession no.580268
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References and Abstracts
Item 270 Polymat ’94 - Polymer Technologies for Electronics. Conference proceedings. London, 19th-22nd Sept.1994, p.369-74. 6E RECENT ADVANCES IN ENCAPSULATION OF MICROELECTRONICS: MATERIALS AND PROCESSES Wong C P AT & T Bell Laboratories (Institute of Materials) Recent advances in polymeric materials and integrated circuit encapsulants have made high reliability very large scale integration plastics packaging a reality. High performance silicone gel possesses excellent electrical and physical properties for integrated circuit protection. With their intrinsic low modulus and soft gel-like nature, silicone gels have become very effective encapsulants for larger, I/O, wire-bonded and flip-chip VLSI chips. Integrated circuit technological trends are reviewed, together with integrated circuit encapsulation materials and processes. Emphasis is placed on the high performance silicone gel, epoxies and polyimides, their chemistry and use as VLSI device encapsulants for single and multi-chip module applications.10 refs. USA
Accession no.579676 Item 271 Medical Device Technology 7, No.1, Jan/Feb.1996, p.16-8 EVALUATING SILICONE TUBING Hibberd S Silicone Altimex Ltd. Concerns associated with the use of silicone tubing in medical pumping operations are addressed. In particular, the quantity of extractables that are produced during use is examined in pumping trials which are performed to determine the life span of two types of silicone tubing; platinum cured and peroxide cured. 2 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.579590 Item 272 Macplas International Aug.1995, p.127 SILICONES AND MOULDS The advantages of using silicone rubber for moulds is described. GE SILICONES EUROPEAN COMMUNITY; EUROPEAN UNION; ITALY; WESTERN EUROPE
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Item 273 Plastics and Rubber Weekly No.1610, 3rd Nov.1995, p.12 GERMAN MOULDER UPS LSR CONTROL Woco reports that it is regularly achieving shot weight standard deviations of less than 0.2% from its Arburg Allrounder liquid silicone rubber injection moulding system. In one test, which lasted almost three hours, seal covers for a car central locking system weighing 5.542g were produced with a standard deviation of 0.013g. The Woco machine features Selogica control and a special 15mm screw LSR injection unit. This latter unit is equipped with a spring-loaded non-return valve which prevents material from flowing back into the screw, enabling a high shot weight consistency and a good surface finish to be achieved even without running a material cushion. ARBURG UK LTD.; WOCO EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.568235 Item 274 Advanced Materials for Optics & Electronics 5, No.4, July-Aug.1995, p.199-213 COUPLING MONOLAYERS FOR PROTECTION OF MICROELECTRONIC CIRCUITS Fabianowski W; Jaccodine R; Kodnani R; Pearson R; Smektala P Lehigh,University Two polymeric coatings, a silicone gel (Dow Corning 6646) and an epoxy resins (Dexter FP 4402), were globtop coated onto representative microelectronic circuits, AT & T Triple Track Testers(TTTs), and subjected to a Pressure Cooker Test. Coupling monolayers were selfassembled on the TTTs prior to encapsulation to improve the moisture protection capabilities of the coatings. Leakage current measurements were carried out in order to evaluate the effect of applied monolayers on the moisture protection capability. The moisture protection capability was assessed in short-term and long-term leakage current measurements. 16-Mercaptohexadecanoic acid and gamma-aminopropyltriethoxysilane monolayers, in combination with silicone gel and epoxy resin, respectively, exhibited very good moisture protection performance. 29 refs. DOW CORNING CORP.; DEXTER CORP.; AT & T BELL LABORATORIES USA
Accession no.566576 Item 275 Nippon Gomu Kyokaishi 67, No.6, 1994, p.411-20 Japanese PRESSURE-SENSITIVE CONDUCTIVE RUBBERS (ROAD SENSORS)
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References and Abstracts
Kanamori K Yokohama Rubber Co.Ltd.
EPIDERMIS RP12 Giridhar G; Myrvik Q N; Gristina A G Medical Sciences Research Institute
The structure and requirements of silicone-based pressuresensitive conductive rubbers are described, particularly for those used in road sensors for vehicle-sorting systems. 7 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology.
USA
JAPAN
Accession no.564210
Accession no.565957 Item 276 Patent Number: US 5412014 A 19950502 FIRE RETARDANT RESIN COMPOSITIONS Romenesko D J Dow Corning Corp. A free-flowing silicone polymer powder, which has an average particle size of 1 to 1000 microns and is prepared by mixing a polydiorganosiloxane with a silica filler, and a phosphorus-based fire retardant compound are uniformly dispersed in an organic resin using conventional equipment, such as a single screw extruder. The resulting resin composition shows a significant improvement in fire retardancy but does not exhibit the severe deterioration of impact resistance incurred when the resin is modified with only phosphorus-based fire retardant. USA
Accession no.564948 Item 277 Advanced Materials for Optics & Electronics 4, No.2, March-April 1994, p.95-127 POLYMERIC SILICON-CONTAINING RESIST MATERIALS Miller R D; Wallraff G M IBM Research Division A review of silicon-containing bilayer and trilayer photoresist technology is presented. Multilayer resist processes of this type are shown to rely on pattern generation in a thin imaging layer, followed by pattern transfer to the thick planarising underlayer by oxygen reactive ion etching. The review concentrates on materials in which the silicon is an integral part of the polymer and does not specifically address photoresists where silicon is incorporated in a post-imaging process step (such as top-surface-imaging resists). 147 refs. USA
Accession no.564760
The effect of PMMA, titanium alloy, and silicone discs on the capacity of rabbit alveolar macrophages to kill RP12 strain of Staphylococcus epidermis was studied invitro. 18 refs.
Item 279 Journal of Applied Biomaterials 6, No.3, Fall 1995, p.153-60 SELF-REPORTED SIGNS AND SYMPTOMS IN BREAST IMPLANT PATIENTS WITH NOVEL ANTIBODIES TO SILICONE SURFACE ASSOCIATED ANTIGENS (ANTI-SSAA(X)) Kossovsky N; Gornbein J A; Zeidler M; Stassi J; Chun G; Papasian N; Nguyen R; Ly K; Rajguru S California,University In a pilot study performed several years ago involving about 350 women, it was observed that a small subpopulation of silicone breast implants exhibited antibodies with binding avidities for synthetic macromolecular complexes of silicone surface charged adsorbed antigens. These antibodies were unique to breast implant patients and were not found in either age matched healthy patients or rheumatic diseased patients who did not have silicone implants. The present study was undertaken to determine if these antibodies might have any clinical significance and if the model of silicone surface associated antigens might help rectify the discrepancy between the various data pools. 60 refs. USA
Accession no.562154 Item 280 Journal of Biomedical Materials Research 29, No.9, Sept. 1995, p.1129-40 AGEING OF SILICONE RUBBER BIOMATERIALS WITH NMR Pfleiderer B; Xu P; Ackerman J L; Garrido L Harvard Medical School; Cincinnati,University Multinuclear NMR was used to characterise the ageing process of silicone rubber-based biomaterials after longterm implantation. The migration of free silicone from the implants to adjacent tissue was also determined. 35 refs. USA
Item 278 Journal of Biomedical Materials Research 29, No.10, Oct.1995, p.1179-83 BIOMATERIAL-INDUCED DYSFUNCTION IN THE CAPACITY OF RABBIT ALVEOLAR MACROPHAGES TO KILL STAPHYLOCOCCUS
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Accession no.561605 Item 281 Biomaterials 16, No.15, 1995, p.1193-7 INFLUENCE OF DIMENSIONAL STABILITY OF
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References and Abstracts
IMPRESSION MATERIALS ON THE PROBABILITY OF ACCEPTANCE OF A PROSTHETIC RESTORATION Pamenius M; Ohlson N G Karolinska Institute
Item 284 Design Engineering July/Aug.1995, p.13 RHEOLOGICAL FLUIDS GIVE BIRTH TO INTELLIGENT SHOCK ABSORBERS
The accuracy of rubber impression materials was evaluated by taking impressions of a steel model, pouring it with stone and comparing certain measurements between steel and stone models. It is said that acceptance is achieved when the difference in measurements is within permissible limits defined by clinical criteria. Data are given for silicone polymer and polyether impression materials. 18 refs.
It is reported that the cars of the future may well have shock absorbers that adapt automatically to road conditions. Bayer has already made some progress in this area by carrying out its first tests on shock absorbers with electrorheological fluids (ERFS). These low-viscosity ‘intelligent fluids’ become highly viscous upon application of an electrical field. Details are given of the company’s Rheobay fluid, which is based on a nonaqueous dispersion of spherical polymer particles in Baysilone Fluid M, a silicone liquid. BAYER AG
SCANDINAVIA; SWEDEN; WESTERN EUROPE
Accession no.560913 Item 282 Injection Molding 3, No.8, Aug.1995, p.66-7 BOTTOM-LINE BENEFITS OF COLD RUNNER LIM Kirkland C Kipe Molds claims that users of the liquid injection moulding process should weigh the cost and complexity of cold runner tooling against the cost of non-recyclable liquid silicone rubber scrap. Cold runner moulds for liquid silicone rubber can cost two to three times more than moulds for conventional runner systems. The elimination of waste with a costly raw material is likely to provide a competitive edge. Details are given. KIPE MOLDS INC. USA
Accession no.560597 Item 283 Rubbercon ’95. Conference Preprints. Gothenburg, 9th-12th May 1995, Paper D1, pp.5. 012 SYNTHETIC VERSUS NATURAL POLYMERS IN THE BIOLOGICAL ENVIRONMENT Yannas I V Massachusetts,Institute of Technology (Nordic Council of Rubber Technology) A comparison is made of interactions occurring between body tissue and synthetic and natural biomaterials used in implants. It is shown that implants based on non-degradable polymers such as silicone rubber induce the synthesis of a fibrous capsule on their surface, whereas degradable polymers obviate the formation of a fibrous capsule. Certain natural polymers, such as highly porous graft copolymers of type I collagen and chondroitin sulphate (a glycosaminoglycan), induce the regeneration of missing tissue rather than the synthesis of scar tissue. SCANDINAVIA; SWEDEN; USA; WESTERN EUROPE
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EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.560165 Item 285 Patent Number: US 5391336 A 19950221 METHOD FOR FABRICATING FOAM GASKETS Akitomo H; Nozoe T; Shinmi H Dow Corning Toray Silicone Co.Ltd. A method for fabricating foam gaskets is characterised in that during the separate transport and subsequent mixing in an enclosed chamber of the base and curing agent portions of a two part foamable and curable organosiloxane composition an inert gas is injected in an amount of 1-50 ml per 100 g of the total curable organosiloxane composition. The gas is injected into either the base portion, the curing agent or during or immediately after mixing of the two portions, and the resultant foamable composition is then extruded from a nozzle onto the seal region of the substrate and cured while foaming. JAPAN
Accession no.557022 Item 286 Journal of Biomedical Materials Research 29, No.7, July 1995, p.849-56 VISCOELASTIC AND ADHERENCE PROPERTIES OF DENTAL RELINING MATERIALS Buch D; Wehbi D; Roques-Carmes C ENSMM The viscoelastic properties of acrylic resin, silicone resin and EVA copolymer dental relining materials were studied comparatively. Their behaviours were investigated by in vitro tests that simulate the masticatory cycle. An attempt was made to correlate the experimental data to the viscoelastic energy loss observed when instability of the prosthetic structure occurs. 19 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.555450
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References and Abstracts
Item 287 Kautchuk und Gummi Kunststoffe 48, No.6, June 1995, p.443-7 UPDATED COMPARISON BETWEEN TOP PERFORMANCE ELASTOMERS IN AUTOMOTIVE APPLICATIONS Meyers G EniChem Details are given of comparisons between high performance elastomers used in the automotive industry. Basic mechanical properties, heat ageing, oil resistance and low temperature properties are described for NBR, acrylic rubber, ethylene acrylic rubber, hydrogenated NBR, chlorosulphonated PE, epichlorohydrin rubber, and silicone rubber. 5 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; ITALY; WESTERN EUROPE
Accession no.554894 Item 288 Patent Number: US 5380478 A 19950110 METHOD FOR PREPARING SILICONE MOULD TOOLING East D A Spraying of high viscosity silicone moulding compositions is described, together with cured silicone moulds or tools formed by the process that allow for near perfect transfer of details from a surface to a moulded object. USA
Accession no.554039 Item 289 Patent Number: US 5376308 A 19941227 COATING SOLUTION FOR FORMING TRANSPARENT CONDUCTIVE COATING AND PROCESS FOR PREPARING SAME Hirai T; Komatsu M; Nakashima A; Abe Y; Iwasaki Y Catalysts & Chemicals Industry Co.Ltd. A conductive substrate is described, coated with a transparent conductive coating prepared by dispersion in water and/or organic solvent of conductive particles having (a) an average particle diameter of not more than 500 Angstroms, in which (b) more than 60 wt.% of particles have a diameter of not more than 600 Angstroms, (c) not more than 5 wt.% of particles have a particle diameter of not more than 100 Angstroms and (d) not more than 15 wt.% of particles have a particle diameter of more than 1000 Angstroms. There is a matrix comprising a silica polymer having an average degree of polymerisation of 1,500-10,000. The coatings have excellent adhesion and surface smoothness and also excellent durability and transparency. Display devices using the transparent conductive substrates as the display panel have excellent resolving power, and give constantly clear and sharp images. JAPAN
Accession no.553395
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Item 290 Patent Number: US 5366806 A 19941122 INTEGRATED THERMOPLASTIC RESIN/ SILICONE RUBBER ARTICLES AND METHOD FOR MAKING Fujiki H; Shudo S Shin-Etsu Chemical Co.Ltd. An integrated thermoplastic resin/silicone rubber article is prepared by modifying a thermoplastic resin with a silicon-containing compound in monomer or polymer form, moulding the thermoplastic resin into a shape, contacting an uncured silicone rubber with the moulded thermoplastic resin, and curing the silicone rubber at a temperature below the softening point of the thermoplastic resin. The article in which the thermoplastic resin is firmly united with the silicone rubber is useful in electric, electronic and automotive applications while taking advantage of the inherent reliability in heat resistance, weather resistance and electrical properties of the silicone rubber. JAPAN
Accession no.552555 Item 291 Rubber World 212, No.2, May 1995, p.20/59 AEM - EXTENDED AGEINGS IN SELECTIVE AUTOMOTIVE FLUIDS Dobel T M; Kotz D A DuPont Co. Changes in the automotive industry are increasing the demands for higher performance seal and gasket materials in both the engine and transmission. Moulded rubber gaskets, carrier gaskets and moulded-in-place technologies have become the preferred sealing systems. The vast majority of these newer gasket designs are made from silicone (VMQ) rubber. The use of ethylene acrylic elastomers (AEM) in powertrain applications has steadily increased in recent years, mainly because of their good balance of high and low temperature properties and oil resistance. This article compares four AEM polymers, three of them new grades, with VMQ and polyacrylate. Extended ageing studies in both engine oil and automatic transmission fluid are used to demonstrate the merits of AEM polymers over the long term for powertrain gaskets. 2 refs. USA
Accession no.552488 Item 292 Revue Generale des Caoutchoucs et Plastiques No.734, Sept.1994, p.68-70 French SURFACE DEFECTS AND MICROSTRUCTURE OF HEAT CURABLE SILICONE ELASTOMERS Varlet J; Pouchelon A; Bourrain P; Joachim F
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References and Abstracts
Rhone-Poulenc SA Results are presented of a capillary rheometer study of the influence of extrusion conditions and rheological properties on defects occurring on the surface of heat curable polydimethyl siloxane extrudates. 4 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.552429 Item 293 Revista de Plasticos Modernos 68, No.458, Aug.1994, p.173-80 Spanish DISPERSED ELECTROMAGNETIC SYSTEMS. II. POLYMERS USED IN THEIR MANUFACTURE AND THEIR APPLICATIONS Davidenko N; Orlov D V; Sastre R Havana,University; Edys; Instituto de Ciencia y Tecnologia de Polimeros A survey is made of polymers used in magnetic fluids, including polysiloxanes and a variety of plastics, and of a number of uses of these systems, such as hermetic seals, vibration dampers, lubricants and medical and pharmaceutical applications. 67 refs. CUBA; EUROPEAN COMMUNITY; EUROPEAN UNION; RUSSIA; SPAIN; WESTERN EUROPE
Accession no.552411 Item 294 147th Meeting, Spring 1995, Conference Preprints. Philadelphia, Pa., 2nd-5th May 1995, Paper 57, pp.55. 012 CHARACTERISING RUBBER ELASTIC BEHAVIOUR FOR FINITE ELEMENT MODELLING Chouchaoui B; Ulrich E Gecamex Technologies Inc. (ACS,Rubber Div.) Silicone and fluorosilicone rubbers were characterised for finite element analysis in simple Shore A deformation modes using as key properties the polynomial and Ogden strain energy density functions. The influence of material data on the quality of model representation of automotive ring gaskets and grommet fasteners was examined. The predicted force-deflection characteristics satisfactorily compared to empirical data when proper material models were selected. Issues such as mesh density, element type and dimensional tolerances in part geometry were also studied. 33 refs. CANADA; USA
Accession no.552390 Item 295 147th Meeting, Spring 1995, Conference Preprints. Philadelphia, Pa., 2nd-5th May 1995, Paper 3, pp.22. 012
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USE OF SILICONE RUBBER ON DISCARDING SABOT PROJECTILES Walker F J Alliant Techsystems Inc. (ACS,Rubber Div.) The application of liquid, high consistency and pumpable silicone rubbers in gas seals for discarding sabot projectile assemblies is discussed. An examination is made of the properties required of such seals, processes used in their manufacture, and methods for bonding silicone rubber to steel, aluminium and plastics inserts used in this application. 7 refs. USA
Accession no.552346 Item 296 Journal of Biomedical Materials Research 29, No.5, May 1995, p.583-90 ASSESSMENT OF VIABILITY AND PROLIFERATION OF IN-VIVO SILICONEPRIMED LYMPHOCYTES AFTER IN-VITRO RE-EXPOSURE TO SILICONE Ciapetti G; Granchi D; Stea S; Cenni E; Schiavon P; Giuliani R; Pizzoferrato A Bologna,Istituti Ortopedici Rizzoli The functional response of peripheral blood lymphocytes isolated from 22 patients with silicone gel-filled breast implants was assessed after in-vitro re-exposure to silicone. Using cell culture test methods to quantify proliferation and viability and/or activation of lymphocyte microcultures, i.e. the uptake of tritiated thymidine and the reduction of formazan salts, interesting assay data were obtained. 18 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; ITALY; WESTERN EUROPE
Accession no.551618 Item 297 Journal of Biomaterials Science : Polymer Edition 7, No.2, 1995, p.147-57 REVIEW. RHEUMATIC DISORDERS IN PATIENTS WITH SILICONE IMPLANTS: A CRITICAL REVIEW Bridges A J Wisconsin,University; Middleton W.S.,Memorial Veterans Admin.Hospital More than 1000 patients with rheumatic disorders and silicone implants have been reported. The clinical features of patients with scleroderma, inflammatory myositis, systemic lupus erythematosus and silicone implants are discussed. The clinical features of the most common rheumatic disorder associated with silicone implants, the ‘silicone implant associated syndrome’ are introduced. In addition, other local regional, and neurological disorders associated with silicone implants are discussed. This comprehensive clinical review provides the clinician
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References and Abstracts
with information regarding the common symptoms, signs and laboratory features of rheumatic disorders of patients with silicone implants. 50 refs. USA
Accession no.551516 Item 298 Journal of Biomaterials Science : Polymer Edition 7, No.2, 1995, p.133-45 SILICONE BREAST IMPLANTS AND AUTOIMMUNITY: CAUSATION, ASSOCIATION, OR MYTH? Brautbar N; Campbell A; Vojdani A Southern California,University; Texas,University; Drew,University of Medicine & Science In-vivo and in-vitro studies, case reports and population studies show that (i) silicone is immunogenic, (ii) silicone is biodegradable and transported via the reticuloendothelial system to distant locations, (iii) silicone breast implants leak and in turn silicone migrates outside the breast tissue, (iv) case reports and population studies document an autoimmune reaction and immunological dysfunction in patients with silicone breast implants, (v) these immunological abnormalities and symptoms are reversible upon removal of the breast implants (in 50-70% of cases). The criteria to establish medical causation are defined, and based on those criteria it is concluded that silicone breast implants cause immunological disease. 55 refs. USA
Accession no.551515 Item 299 Journal of Biomaterials Science : Polymer Edition 7, No.2, 1995, p.115-21 REVIEW. DO SILICONE BREAST IMPLANTS CAUSE AUTOIMMUNE RHEUMATIC DISEASES? Smith H R Case Western Reserve University A spectrum of illnesses ranging from local symptoms to systemic disease is seen in some patients with silicone breast implants. However, it remains to be determined whether such illnesses in these patients are coincidentally associated or are secondary to the implants. This article reviews data relating to this issue. 41 refs. USA
Accession no.551513 Item 300 Journal of Biomaterials Science : Polymer Edition 7, No.2, 1995, p.101-13 REVIEW. PHYSICOCHEMICAL AND IMMUNOLOGICAL BASIS OF SILICONE PATHOPHYSIOLOGY
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Kossovsky N; Frieman C J California,University Silicones, model biomaterials with almost ubiquitous applications, are the focus of a contentious debate. In this review, both established physicochemical phenomena and immunological phenomena are considered, then the human clinical phenomena that relate directly to them are considered. Two competing theories of the biological activity of silicones are explored, and weaknesses in the various arguments that silicone is inert are discussed. 91 refs. USA
Accession no.551512 Item 301 Journal of Materials Science.Materials in Medicine 6, No.3, March 1995, p.177-80 SILICONE ELASTOMERS: STUDY OF THEIR MESH SIZE BY THERMAL ANALYSIS Moreau J C; Madelmont G; Leclerc B; Mazan J; Couarraze G Paris-Sud,Universite Silicone elastomers are often used as a base for controlledrelease systems for drugs and the modulation of drug diffusion by varying the mesh size of a silicone elastomer network has previously been studied. In this work, the effect of vulcanisation conditions and chemical modifications on the network mesh size was investigated by thermal analysis and measurement of swelling ratio. The influence of these parameters on the diffusion of model drugs was also studied. 15 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.549399 Item 302 Patent Number: EP 640660 A2 19950301 MONITOR PUTTY Gibbon R JMK International Inc. An apparatus for providing manipulative physical therapy includes a first mass of a putty including a reaction product of siloxane with a boron- or tin-containing compound and a polysiloxane. At least one additional mass of the putty is provided to the patient, the mass adaptable to be manually combined by the patient with the first mass until a uniform colour is achieved. The apparatus provides a means by which the progress of manipulative physical therapy may be monitored, as a uniform colour in the combined mass will be achieved only after extensive manipulation. USA
Accession no.545000 Item 303 Macplas International
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April 1994, p.122-3 LIQUID SILICONE RUBBER FOR HIGH PERFORMANCE Schulze M Bayer AG Applications of liquid silicone rubbers in injection moulded components and heat resistant protective clothing are described. Recycling and other environmental aspects of these materials are also discussed. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.544318 Item 304 Revue Generale des Caoutchoucs et Plastiques No.729, Feb.1994, p.64-7 French RUBBER TEATS: MATERIALS DEVELOPMENTS AND REGULATIONS Cardinet C; Niepel H Hutchinson SA; Mapa GmbH Materials used in teats for baby feeding bottles, including NR, silicone rubber and styrene-butadiene block copolymer thermoplastic elastomers are examined, and processes and additives used in the manufacture of teats are described. A survey is made of regulations in a number of countries covering the toxicological characteristics of such materials, and of test methods used to determine the migration and extractability of additives and the presence of specific compounds, with particular reference to nitrosamines. 5 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; GERMANY; WESTERN EUROPE; WORLD
Accession no.544277 Item 305 Reinforced Plastics 39, No.3, March 1995, p.16 FAST AND EASY PROTOTYPING OF COMPLEX PARTS Protomix from Camattini is an easy, cheap and fast tool for rapid prototyping. The system consists of a vacuum chamber with a four-way pneumatic injection system controlled by a pneumatic gun for product mixing and for injection into the mould, a 24 or 36 element static mixer, twin cartridges containing the different Protomix PU products designed to ensure consistent prototyping, and a transparent silicone rubber which has a high degree of dimensional stability and low shrinkage for mould production. CAMATTINI SPA EUROPEAN COMMUNITY; EUROPEAN UNION; ITALY; WESTERN EUROPE
Accession no.544136 Item 306 Urethane Plastics and Products 25, No.1, Jan.1995, p.1-2
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ROGERS CORPORATION SPOTLIGHTS HIGH PERFORMANCE ELASTOMER MATERIALS AND COMPONENTS Properties and applications of two high performance elastomer materials from Rogers Corp. are discussed in some detail. Poron cellular urethane and silicone materials are reported to be used for products such as gaskets for disc drives, vibration isolators in machinery, and airbag detonator protection devices. The company’s Endur range of elastomeric materials are said to be used in applications such as components for document handling in office equipment and extended component life is now reported to be offered by the new polyisoprene version of Endur products. ROGERS CORP.,PORON MATERIALS DIV. USA
Accession no.542377 Item 307 Antec ’94. Conference Proceedings. San Francisco, Ca., 1st-5th May 1994, Vol.I, p.894-6. 012 DETERMINING MOULD FILLING ANALYSIS ACCURACY FOR THERMOSET MATERIAL Mutkus E A Pennsylvania,State University (SPE) Pressures predicted by mould filling analysis software for the moulding of silicone rubber were compared with results from the actual moulding process. The predictions were within 10% of the actual process pressures. USA
Accession no.541223 Item 308 Journal of Biomedical Materials Research 29, No.1, Jan.1995, p.59-63 KINETIC STUDY OF RELEASE OF SILICON COMPOUNDS FROM POLYSILOXANE TISSUE EXPANDERS Raimondi M L; Sassara C; Bellobono I R; Matturri L Milan,University The release behaviour of commercial tissue expanders was examined by the determination of the chemical nature and its modification after in vivo use by ESCA, and a kinetic examination of silicon compounds released by the biomaterial in physiological saline. The correlation of kinetic and physicochemical tests with the in vivo behaviour is discussed. 9 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; ITALY; WESTERN EUROPE
Accession no.538596 Item 309 Antec ’94. Conference Proceedings.
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References and Abstracts
San Francisco, Ca., 1st-5th May 1994, Vol.I, p.234-8. 012 DEVOLATILISATION OF PDMS GUMS: A PERFORMANCE COMPARISON OF CO- AND COUNTER-ROTATING TWIN-SCREW EXTRUDERS Powell K G General Electric Co.,Corporate R & D (SPE) A study was made of the performance of a co-rotating twin-screw extruder and a non-intermeshing counterrotating twin-screw extruder in the devolatilisation of polydimethyl siloxane gums. Hydrodynamic differences between the extruders were reflected in their devolatilisation performance as a function of operating parameters. The concept of normalised residuals based on Latinen’s wiped film model was a useful method for classifying devolatilisation problems and simplifying process optimisation. 11 refs. USA
Accession no.537964 Item 310 Antec ’94. Conference Proceedings. San Francisco, Ca., 1st-5th May 1994, Vol.I, p.94-9. 012 USE OF DIE MODELLING TO IMPROVE THE MANUFACTURING PROCESS FOR EXTRUDED SILICONE RUBBER Reese C; Marchal T; Marchal J M Dow Corning Corp.; Polyflow SA (SPE) Flow analysis software was used to develop a die and process parameters for the extrusion of complex threehole silicone rubber tubing. The resulting modified die mandrel gave satisfactory match-up of extrudate shape to the desired shape, increased product quality and production rate and reduced set-up time. 3 refs. BELGIUM; EUROPEAN COMMUNITY; EUROPEAN UNION; USA; WESTERN EUROPE
Accession no.537941 Item 311 Plastiques Flash No.273, July/Aug.1994, p.40-2 French LIQUID SILICONES TODAY The properties, processing and applications of liquid silicone rubbers are reviewed. BAYER AG; DOW CORNING CORP.; WACKERCHEMIE GMBH; RHONE-POULENC SA; BEUCHAT G.; M2S EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; GERMANY; USA; WESTERN EUROPE
Accession no.537919
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Item 312 Revista de Plasticos Modernos 68, No.457, July 1994, p.22-9 Spanish SYNTHESIS AND STUDY OF THE OPTICAL AND ELECTRONIC PROPERTIES OF POLYSILANES. II. Peinado C; Catalina F; Schnabel W Instituto de Ciencia y Tecnologia de Polimeros; HahnMeitner-Institut Berlin GmbH An examination is made of the electronic transport and non-linear optical properties of polysilanes. Uses of these polymers as photoinitiators in polymerisation processes and precursors for silicon carbide and in microlithography, charge transport, photoconduction and non-linear optical applications are described. 26 refs. (Part I: Ibid., 67, No.456, June 1994, p.567-76). EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; SPAIN; WESTERN EUROPE
Accession no.537904 Item 313 Industria della Gomma 38, Nos.7/8, July/Aug.1994, p.42-3 Italian SILICONE RUBBERS FOR THE TREATMENT OF FABRICS Muller J Wacker-Chemie GmbH Applications of silicone rubbers in the coating of fabrics for use in cable insulation, conveyor belting, protective clothing and automotive air bags are examined. The Elastosil range of silicone rubbers produced by WackerChemie is briefly described. SILMIX SPA EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; ITALY; WESTERN EUROPE
Accession no.537903 Item 314 Polymer Degradation and Stability 46, No.2, 1994, p.241-6 STABILITY OF FIVE PLASTICS USED IN MEDICAL DEVICES TO OXIDATION PRODUCED BY COPPER OR IRON IONS AND REDUCING AGENTS Sagripanti J-L; Hughes-Dillon M K US,Food & Drug Administration Polyurethane, silicone rubber, polyamide, PVC, and PE were exposed to metal-based formulations containing copper ions or iron ions. Oxidation effects are discussed. 17 refs. USA
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Item 315 Journal of Biomedical Materials Research 28, No.12, Dec.1994, p.1433-8 SPLENIC RESPONSE TO SILICON DRAIN MATERIAL FOLLOWING INTRAPERITONEAL IMPLANTATION Guo W; Willen R; Liu X; Odelius R; Carlen B Lund,University Silicone rubber drain fragments were implanted intraperitoneally to study the splenic response. Four days after implantation samples of spleen and implanted rubber fragments were retrieved and studied by SEM and energy dispersive X-ray microanalysis. 7 refs. SCANDINAVIA; SWEDEN; WESTERN EUROPE
Accession no.536611 Item 316 Polymers for Advanced Technologies 5, No.9, Sept.1994, p.473-8 CYCLIC POLYMERS: PAST, PRESENT AND FUTURE Semlyen J A; Wood B R; Hodge P York,University; Manchester,University Methods for characterising cyclic polymers are illustrated by reference first to dilute solution methods for cyclic polydimethylsiloxane (PDMS) and then to the entrapment of cyclic polymers in networks. Preparative routes to cyclic polymers are reviewed, including ring-chain equilibration reactions, coupling and condensation reactions and new methods using polymer-supported reagents. Some of the properties of PDMS are discussed, including differences between ring and chain polymer properties such as their melt viscosities and Tgs. Methods for preparing the first polymeric catenanes are described, using polymer-supported reagents. Further directions for cyclic polymer chemistry are indicated, including topological polymer chemistry. 43 refs. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.535233 Item 317 Journal of Advanced Materials 26, No.1, Oct.1994, p.2-8 MOULDING OF COMPLEX COMPOSITE PARTS UTILISING MODIFIED SILICONE RUBBER TOOLING Weiser E S; Baucom R M Georgia,Institute of Technology; US,NASA,Langley Research Center Cast silicone rubber was utilised as a tooling aid to apply pressure to complex composite parts during cure. Emphasis is given to the governing formula for rubber
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expansion and innovative methodology for precise control of the expansion rate. 6 refs. USA
Accession no.533922 Item 318 Chemistry & Industry No.17, 5th Sept.1994, p.668 FIRST FOR RAMAN SPECTROSCOPY The US Armed Forces Institute of Pathology (AFIP) claims to be the first to use Raman spectroscopy to identify silicone and other foreign materials in breast tissue. The article supplies details of a Raman microprobe which provides a non-destructive technique for examining tissue on a molecular level. The article includes brief details of three different types of breast implants analysed using Raman spectroscopy. US,FOOD & DRUG ADMINISTRATION; US,ARMED FORCES INSTITUTE OF PATHOLOGY USA
Accession no.533709 Item 319 Plastics and Rubber Weekly No.1560, 4th Nov.1994, p.7 RUBBER FLIES SKY HIGH RE Components has developed a new silicone rubber compound for cable support bushes for the new V2500 turbofan aircraft engine. The bushes hold wiring in place in harnesses positioned from near the centre of the engine to the intake fan. The components had to meet a specification set by the National Society of British Aerospace Companies for tolerance of extremes of temperature. Northern Rubber and British Aerospace have cooperated to produce an improved thermally insulated air ducting system for Eurofighter 2000 aeroplanes. The silicone rubber hose system helps keep equipment cooling air and cockpit air conditioning air at the right temperature. The insulation material is a sound-absorbing, flame-retardant PU foam with a tough film coating. RE COMPONENTS LTD.; NORTHERN RUBBER CO.LTD. EUROPEAN COMMUNITY; EUROPEAN UNION; UK; WESTERN EUROPE
Accession no.533621 Item 320 Kunststoff Journal 28, No.3, June 1994, p.44 German RAPID PROTOTYPES The MCP vacuum casting method is an effective and relatively cheap way of producing plastic prototypes and small batches. A casting mould is made of silicon and
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References and Abstracts
casting resin added in a vacuum casting machine and then cured in a heating chamber. HEK GMBH EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.532992
Item 324 Philadelphia, Pa, 1993. 1/11/93. 6J22 ASTM C 1115-. SPECIFICATION FOR DENSE ELASTOMERIC SILICONE RUBBER GASKETS AND ACCESSORIES American Society for Testing & Materials ASTM C 1115-
Item 321 Plastverarbeiter 45, No.10, Oct.1994, p.26 German IN-SITU SEALS FOR ENGINE CONSTRUCTION
Details are given of elastomeric silicone rubber for gaskets and accessories for use in glazing and sealing applications. Photocopies and loans of this document are not available from Rapra. It may be purchased from BSI. Please contact Rapra for further details.
Using a two-component metering unit, it is possible to extrude silicon seals directly onto components, e.g. rocker arm covers, for automobile engine construction.
USA
EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Item 325 Antec ’93. Conference Proceedings. New Orleans, La., 9th-13th May 1993, Vol.III, p.298890. 012 NEW ARTIFICIAL SKIN FACE MASK FOR MEASUREMENT OF LACERATION POTENTIAL McKinney R; Moody D Triangle Research & Development Corp. (SPE)
Accession no.532968 Item 322 Rubber and Plastics News 24, No.4, 19th Sept.1994, p.6 IMPLANT MAKERS OK 4.25 US BILLION DOLLAR SETTLEMENT Moore M The lawsuits taken out against manufacturers of silicone gel breast implants concern over 90,000 women who have entered a pact which promises them reimbursement of between 105,000 and 1.4 million US dollars each over the next 30 years. Dow Corning and Bristol-Meyers Squibb Co. affirmed their commitment to the agreement and the deadline date of 9th September for withdrawal from the agreement, passed without a defendant company giving official notice of withdrawal, it is reported. DOW CORNING CORP.; BRISTOL-MEYERS SQUIBB CO. USA
Accession no.531787 Item 323 Rubber and Plastics News 24, No.3, 12th Sept.1994, p.3 LAWSUITS CLAIM NORPLANT DIFFICULT TO REMOVE Moore M According to the lawsuit filed recently against WyethAyerst Laboratories, their product, a contraceptive system of implanted capsules tradenamed Norplant, cannot be removed without extreme pain and permanent scarring in some cases. The article supplies brief details of the capsules, made from a patented siloxane polymer, and the lawsuit. WYETH-AYERST LABORATORIES USA
Accession no.531296
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Accession no.530179
An account is given of the development of an artificial skin face mask for dummies used in the measurement of facial laceration potential in trauma and injury research and automotive component testing. Masks were injection moulded in PU and silicone polymer compounds, and tests indicated that a modified two-component silicone had the best potential for this application. Experiments showed that such masks could provide approximately the same laceration index score as double-layer chamois whilst minimising changes in the dynamic impact response of the dummy. 7 refs. APM INC.; BIRMINGHAM,UNIVERSITY; RENAULT SA EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; UK; USA; WESTERN EUROPE
Accession no.528840 Item 326 Antec ’93. Conference Proceedings. New Orleans, La., 9th-13th May 1993, Vol.III, p.22807. 012 PRECISION MOULDING WITH THE TIEBARLESS INJECTION MOULDING MACHINE Strohmaier F Engel Canada Inc. (SPE) Technical features and advantages of tiebarless injection moulding machines are described, and reference is made to their use in the flashless moulding of liquid silicone rubber parts.
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References and Abstracts
CANADA; USA
Accession no.524607
solution has been found with interpenetrating network materials based on epoxy and silicone compounds. WORLD
Item 327 Adhasion Kleben & Dichten 38, No.4, 1994, p.26-7 German SEALS EXTRUDED NOT INSERTED The 2K machine extrudes a silicone-based sealing material directly where required, instead of an O-ring being inserted by hand. Measuring and extruding takes a total of 3 seconds. 300,000 engine gear casings have been sealed in this way for Peugeot with a failure rate of zero. Technical details of the robot are given. PEUGEOT SA EUROPEAN COMMUNITY; EUROPEAN UNION; FRANCE; WESTERN EUROPE
Accession no.522700
Accession no.522109 Item 330 Rubber and Plastics News 23, No.23, 20th June 1994, p.10 JAMAK WRAPS OFFER RELIEVING HEAT Miller J Jamak Fabrication is reported to have introduced Red-EHeat, a new range of therapeutical wraps containing a microwavable silicone compound. The products are designed to deliver moist heat therapy and orthopaedic support to arthritis and muscle pain sufferers, the JMK International subsidiary claims. Details are given. JAMAK FABRICATION INC.; JMK INTERNATIONAL INC. USA
Item 328 International Polymer Science and Technology 21, No.4, 1994, p.T/26-37 SYNTHESIS OF SILICONE POLYMERS Inoue H Methods of synthesising silicone polymers with polysiloxane chains are reviewed in detail, particularly hydrolytic condensation of chlorosilanes, ring-opening polymerisation of cyclic siloxanes, synthesis of silicones by step-growth reaction (condensation), synthesis of telechelic silicone oligomers by equilibrium polymerisation, synthesis of modified silicones by addition reaction, crosslinking of silicones, and the synthesis of silicone modified polymers with siloxane polymer chains or side chains. 112 refs. Translation of Nippon Gomu Kyokaishi, No.9, 1993, p.660 JAPAN
Accession no.522631 Item 329 European Plastics News 21, No.7, July/Aug.1994, p.20 PROTECTING ELECTRONIC CHIPS Guyot H Most of the discrete semiconductors and integrated circuits in use today are based on silicon and rely on some form of resin encapsulation to ensure reliable operation in real-world environmental conditions. Epoxy compounds dominate with silicones also being used in considerable volumes. Transfer moulding dominates the encapsulation business, with multi-plunger moulding restricted to use with small sized devices. For the new types of products based on large chips, chip makers have been forced to return to single piston injection systems using materials with gel times in excess of 25 seconds. In the search for low shrink, high throughput resins, a
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Accession no.521390 Item 331 Antec ’93. Conference Proceedings. New Orleans, La., 9th-13th May 1993, Vol.II, p.2034-6. 012 SILICONE RUBBER MOULDING: THE WHAT AND WHY Dekker C K Met-L-Flo Inc.,Plas-T-Flo Div. (SPE) The use of silicone rubber moulds for casting PU and epoxy resins is discussed. Aspects of mould making and design and factors affecting mould life are examined. USA
Accession no.520557 Item 332 Berlin, 1992. 1/11/92. 6E1 RUBBER INSULATED CABLES, WIRES AND FLEXIBLE CORDS FOR POWER INSTALLATION - UNBRAIDED HEATRESISTANT SILICONE RUBBER INSULATED CABLES Verband Deutscher Elektrotechniker VDE 0282(PT506) Photocopies and loans of this document are not available from Rapra. It may be purchased from BSI. Please contact Rapra for further details. EUROPEAN COMMUNITY; EUROPEAN UNION; GERMANY; WESTERN EUROPE
Accession no.520334 Item 333 Tokyo, 1993. 1/3/93. 45C
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References and Abstracts
TESTING METHOD FOR ELECTRICAL SILICONE RUBBER COMPOUNDS Japanese Standards JIS-C2123 Photocopies and loans of this document are not available from Rapra. It may be purchased from BSI. Please contact Rapra for further details. JAPAN
Accession no.520220 Item 334 Philadelphia, Pa, 1992. 11/9/92. 6E1 WIRE, ELECTRICAL, SILICONE RUBBER INSULATED, 150 DEG. C, 1000 VOLTS, GLASS BRAID COVERING, ABRASION RESISTANT US,Navy MIL-W-16878/31 Photocopies and loans of this document are not available from Rapra. It may be purchased from BSI. Please contact Rapra for further details. USA
Accession no.518409 Item 335 Philadelphia, Pa, 1993. 10/2/93. 6H1 HOSE AND HOSE ASSEMBLIES, NON METALLIC, SILICONE, POLYESTER AND WIRE REINFORCED (FOR COOLANT AND HEATING SYSTEMS OF DIESEL & GASOLINE POWERED ENGINES) US,Navy MIL-H-62217 Details are given of four types of polyester and wire reinforced, silicone compounded, elastomeric hose, for use in coolant and heating systems of diesel and gasoline engines. Photocopies and loans of this document are not available from Rapra. It may be purchased from BSI. Please contact Rapra for further details. USA
Accession no.518372 Item 336 European Rubber Journal 176, No.5, May 1994, p.24-5 EMI SHIELDING: A SILVER LINING? Dunlop Precision Rubber and James Walker & Co. have both recently introduced new ranges of high performance conductive elastomers for EMI shielding seals, primarily needed in aerospace and defence applications. Dunlop Precision’s range is based on silicones and fluorosilicones, with metallic or metal-coated fillers. Materials used as fillers include hollow glass spheres coated with metal, which gives low weight, and metallised fabric. James Walker claims its range of conductive elastomers, using
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silver-coated glass spheres, give the highest performance for cost of any conductive elastomer and will cut the cost of EMI shielding. The company’s Shieldseal 105 material is an alternative to heavier, more expensive conductive elastomers originally designed for military uses, it claims. DUNLOP LTD.,PRECISION RUBBERS DIV.; WALKER J.,& CO.LTD. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.512684 Item 337 New Scientist 142, No.1923, 30th April 1994, p.21 POLYMER PUTTY MAKES FOR SAFER TUMOUR TREATMENT Beard J A polymer putty has been developed which will be of use in shielding healthy tissue from the effects of radiation used to treat oral tumours. The putty is made from 9095% metal powder bound together by polysiloxane. The putty can easily be shaped around irregular shaped tumours and also skin melanomas. Further details are given. AMERICAN DENTAL ASSOCIATION HEALTH FOUNDATION; US,NATIONAL INST.OF STANDARDS & TECHNOLOGY USA
Accession no.512191 Item 338 International Journal of Adhesion & Adhesives 14, No.2, April 1994, p.103-7 HYDROTHERMAL STABILITY OF JOINTS, USING A SILICONE RUBBER ADHESIVE, FOR A RANGE OF ADHERENDS OF INTEREST TO MAKERS OF SURGICALLY-IMPLANTED MICROELECTRONIC DEVICES Donaldson P E K London,University College This paper describes a series of accelerated life tests on the adhesion between a convenient silicone rubber (Dow Corning 3140) and a range of adherend materials of which such structures might be made. It appears that bonding is by chemisorption and varies in resistance to degradation in water according to the density of negative charge on the adherend surface. The work is thought to provide the beginnings of a rational process for choosing adherend materials in implant design. 7 refs. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.510798 Item 339 Adhesives Age 37, No.4, April 1994, p.16/22 APPLICATIONS OF CURED-IN-PLACE
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GASKETING TECHNOLOGY DiNicola D; Ledoux R E Robotics Inc. It is reported that for more than two decades, silicone rubber has been the material of choice in many industries for making formed-in-place and moulded-in-place gaskets on products ranging from small appliances to automotive engines. The most common form of sealant has, until recent years, been room temperature vulcanisation. Several case histories are outlined which focus on liquid silicone rubber materials used to form cured-in-place gaskets onto a variety of products. USA
Accession no.509900 Item 340 Journal of Biomaterials Science : Polymer Edition 5, No.4, 1994, p.339-51 CONTROLLED RELEASE OF BETAESTRADIOL FROM BIODEGRADABLE MICROPARTICLES WITHIN A SILICONE MATRIX Brannon-Peppas L Biogel Technology Biodegradable controlled release systems were prepared from biodegradable microparticles of poly(lactic acid-coglycolic acid) containing beta-estradiol in the presence or absence of silicone. The release behaviour of betaestradiol from free microparticles and from microparticles embedded within a silicone matrix was compared with the release behaviour shown by non-encapsulated betaestradiol within a silicone matrix. It was found that incorporating biodegradable microparticles within a silicone matrix lessened the initial burst of release often seen with these types of formulations and provided a controlled rate of drug release. In addition, the release rate of beta-estradiol from biodegradable microparticles within silicone was higher than for unencapsulated betaestradiol in silicone. This type of formulation could be useful in a number of instances, such as release of drugs from implants for which a simple drug-silicone formulation did not yield desired release behaviour, formulations which are currently developed for microparticles but which may need to be removed if necessary and implant formulations containing drugs which will not diffuse through silicone. 29 refs. USA
Accession no.508853 Item 341 Modern Plastics International 24, No.3, March 1994, p.20/3 LINE BETWEEN PROTOTYPING, PRODUCTION IS BLURRING Innace J J; Snyder M R
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A recent technical push in rapid prototyping technology is in the area of short production runs that can yield as many as 100 low-cost parts in a matter of days. General Pattern Co. has recently developed an in-house process using RIM equipment. Mox-Med Inc. is specialising in the custom prototyping and manufacture of silicone rubber medical components using the liquid injection moulding process. MCP Systems Inc., a supplier of automatic vacuum casting machines, has a system employing silicone moulds. The company says seven or eight finished PU parts can be produced per day. GENERAL PATTERN CO.; MOXMED INC.; MCP SYSTEMS INC. USA
Accession no.507564 Item 342 IRC ’93/144th Meeting, Fall 1993. Conference Proceedings. Orlando, Fl., 26th-29th Oct.1993, Paper 112, pp.18. 012 INCREASING THE PROFITABILITY OF SILICONE RUBBER MOULDING Tanton R Dow Corning STI (ACS,Rubber Div.) An examination is made of the advantages in terms of increased productivity and reduced production costs of using platinum cure systems in place of peroxides in the moulding of silicone rubber compounds. USA
Accession no.505684 Item 343 Gummibereifung 69, No.7, July 1993, p.54-6 German SILICONE RUBBER SUCCESSFUL IN SEALING JOINTS Silicone rubber, composed of silicon and oxygen rather than carbon, is discussed as a material for seals on aircraft windows and on ovens. The advantages are heat resistance, cold flexibility, good ageing and weathering resistance, resistance to ozone and radiation, electrical insulation. Solid and liquid types of silicone rubber are described. Further applications are listed, e.g. medical tubing, rollers, electric cables. EUROPEAN COMMUNITY; GERMANY; WESTERN EUROPE
Accession no.505580 Item 344 Plastics & Rubber & Composites Processing & Applications 19, No.2, 1993, p.87-92
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References and Abstracts
INJECTION MOULDING OF CUSTOM HIP REPLACEMENT SOCKETS Quek C H; Crawford R J; Orr J F Belfast,Queen’s University An investigation is described of the feasibility of injection moulding hip replacement sockets on a ‘one-off’ basis. A silicone rubber impression was used to reproduce the required socket shape in PMMA within a standard mould backing block. PE was then injected into the mould to produce good quality mouldings, the PMMA mould showing little deformation at the moulding temperature and pressures used. Further process development is required for the orthopaedic application described but the process is offered as a means of injection moulding low numbers of components or for testing prototype mould designs. 9 refs. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.505507 Item 345 Patent Number: WO 9401496 A1 19940120 METHOD AND DEVICE FOR CUSHIONING LIMBS Bracken R L; Winn R A; Riley N L Schering-Plough Healthcare Products Inc. A soft, tacky polysiloxane elastomer, which has specified tackiness, tensile strength, minimum elongation and tear strength values, is disclosed. The elastomer may be made into various cushioning devices with or without a top cover, such as arch support pads, metatarsal pads, heel cushions, sheet padding, insoles, toe-crest pads, heel liners, elbow pads, corn and callus pads, blister pads, bunnion pads and toe pads. USA
Accession no.505382 Item 346 Progress in Organic Coatings 23, No.3, Feb.1994, p.201-36 SYNTHESIS AND APPLICATIONS OF PHOTOCROSSLINKABLE POLYSILOXANES Abdellah L; Boutevin B; Youssef B Montpellier,University This survey reviews the synthesis and curing of polysiloxanes by UV radiation and electron beams. Three main kinds of products are described: those formed by an applied radical mechanism and constituting acrylated polysiloxanes linked by either Si-OC bonds or Si-C bonds, or by urethane acrylated polysiloxanes or by the thiolenes system; those using a cationic mechanism listing the epoxy grafted polysiloxanes, the vinyl and the styrenic corresponding compounds; and a special type of polysiloxane cured by a noble metal or SiH-Si vinyl. In each case, the mechanism, photosensitisers, additives, reactive diluents and apparatus for curing formulations
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are given. Some applications and properties of these products, mainly in the field of coating such as release papers are described. An attempt is made to relate the structure of these kinds of polydimethylsiloxanes to their properties. 149 refs. EUROPEAN COMMUNITY; FRANCE; WESTERN EUROPE
Accession no.503975 Item 347 Nippon Gomu Kyokaishi 66, No.12, 1993, p.890-4 Japanese DETERIORATION OF OIL SEALS AND ANALYSIS Senda K NOK Corp. A discussion is given of the factors such as cracking and abrasion which affect the service life of oil seals made from silicone rubbers, and of their investigation by IR spectroscopy and bench tests. 14 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. JAPAN
Accession no.503825 Item 348 Plastics and Rubber Asia 8, No.49, Dec.1993, p.41 INJECTION MOULDING SILICON RUBBER Sitard F Dr.Boy GmbH The processing of liquid silicone rubber is discussed. The relatively new material is finding acceptance as an alternative to solid silicone rubbers and other organic elastomers. Properties of the material are described, in particular its good ageing resistance, wide temperature tolerance, and electrical properties. The advantages of its processability and high temperature vulcanisation are put to advantage in industrial scale manufacturing of small flexible mouldings. EUROPEAN COMMUNITY; GERMANY; WESTERN EUROPE
Accession no.501025 Item 349 PV International Plastics Magazine 4, No.2, Oct.1993, p.18-9 BACK-FORMING AND LSR PROCESSING IN THE INJECTION MOULDING PROCESS A new injection moulding machine from Krauss-Maffei Kunststofftechnik was presented at the company’s inhouse trade fair 1993. The machine is capable of producing large laminated plastic parts for use, as an example, in inside panellings of cars, in one single
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References and Abstracts
Systems which are used to seal penetrations in fire walls and partitions caused by the passage of cables, pipes and ducts are described. Silicone foam penetration seals are included. These systems prevent the spread of flame, smoke and toxic gases.
operation. It is designated KM 800-5700 VIM based on the vertical injection moulding principle for back-forming applications. The KM 40-190 C2 injection moulding machine also presented, is capable of processing liquid silicone rubber. KRAUSS-MAFFEI KUNSTSTOFFTECHNIK GMBH
EUROPEAN COMMUNITY; UK; WESTERN EUROPE
EUROPEAN COMMUNITY; GERMANY; WESTERN EUROPE
Accession no.496029
Accession no.499130 Item 350 Biomedical Materials Nov.1993, p.7-8 COATED BREAST IMPLANTS FOUND TO RELEASE POSSIBLE CARCINOGEN Research carried out by Bristol-Myers Squibb and supervised by the US Food & Drug Administration is reported to show that silicone breast implants coated with PU foam release a suspected carcinogen. The studies confirm earlier suspicions about the implants, which were marketed under the names of Meme, Replicon and Natural Y before suspension of sales in 1991. BRISTOL-MYERS SQUIBB CO.
Item 353 Revue Generale des Caoutchoucs et Plastiques 70, No.725, Sept.1993, p.71-2 French LIQUID SILICONE RUBBER: MATERIAL OF THE FUTURE Schulze M Bayer AG An examination is made of the vulcanisation, injection moulding, environmental and quality aspects and applications of Silopren LSR liquid silicone rubbers, developed by Bayer AG. EUROPEAN COMMUNITY; GERMANY; WESTERN EUROPE
Accession no.495691
USA
Accession no.498799 Item 351 Nippon Gomu Kyokaishi 66, No.9, 1993, p.660-72 Japanese SYNTHESIS OF SILICONE POLYMERS Inoue H Osaka Municipal Industrial Research Institute A review is given of the reactions of formation of silicone polymers and of the synthesis of silicone-vinyl block copolymers, silicone-polyester block copolymers, silicone-polyamide block copolymers, silicone-modified polyurethane and polyurea, silicone-polycarbonate block copolymers, silicone-PSF, -PES and -PEEK block copolymers, silicone graft copolymers, silicone-modified epoxy resins, silicone IPN and hybrids. 112 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. JAPAN
Accession no.498526 Item 352 Plastics in Telecommunicatons VI. Conference Proceedings. London 16th-18th Sept.1992, p.12/1-12/9. 6E SYSTEMS FOR SEALING FIRE-RATED PENETRATIONS Richards J Dow Corning Hansil Ltd. (PRI)
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Item 354 Advanced Materials 5, No.10, Oct.1993, p.743-6 ELECTROLUMINESCENT DEVICES BASED ON POLY(METHYLPHENYLSILANE) Suzuki H; Meyer H; Simmerer J; Jiping Yang; Haarer D Bayreuth,University The fabrication of high-efficiency light-emitting diodes (LEDs) based on sublimed molecular films has attracted much attention in the search for materials for application in large-area flat-panel displays. Here, multi-layered LEDs based on poly(methylphenylsilane)(PMPS) as the hole transporting material are reported. In contrast to polyphenylenevinylene, PMPS films exhibit a high effective mobility of holes, making the material suitable for fast switching applications. 21 refs. EUROPEAN COMMUNITY; GERMANY; WESTERN EUROPE
Accession no.495629 Item 355 Plastverarbeiter 44, No.9, 1993, p.96/8 German EMBOSSING OF DECORATIVE MATERIALS AND LSR PROCESSING IN THE INJECTION MOULDING PROCESS At its in-house trade fair in 1993, Krauss-Maffei Kunststofftechnik is reported to have presented the following innovations - a new machine concept for production of large laminated plastics parts, e.g. the inside panellings in cars in a single operation; and an injection moulding machine for processing liquid silicone rubber. Details are given.
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References and Abstracts
KRAUSS-MAFFEI KUNSTSTOFFTECHNIK GMBH EUROPEAN COMMUNITY; GERMANY; WESTERN EUROPE
Accession no.495503 Item 356 Journal of Applied Polymer Science 50, No.4, 20th Oct.1993, p.729-33 SWELLING PROPERTIES OF CROSS-LINKED MAXILLOFACIAL ELASTOMERS Andreopoulos A G; Polyzois G L; Evangelatou M Athens,National Technical University; Athens,University Silicone (Cosmesil SM4) specimens cross-linked with various amounts of cross-linking agent were studied in terms of mechanical and swelling behaviour. The measured tensile modulus allowed calculation of the average molecular weight between crosslinks. Equilibrium swelling data were also used, in combination with the molecular weight between crosslinks data, to obtain the interaction parameter of various siliconesolvent systems at 25C. Swelling was studied also for silicone samples with varying network densities in selected solvents such as toluene, ethyl acetate, n-butanol and methyl ethyl ketone. 17 refs. EUROPEAN COMMUNITY; GREECE; WESTERN EUROPE
Accession no.494886 Item 357 China Synthetic Rubber Industry 16, No.5, Sept.1993, p.268-70 Chinese PREPARATION AND PROPERTIES OF SILICONE RUBBER DISPERSION Zhao Mingxing; Dai Mengxian; Wu Ping; Tong Jinquan; Duan Wei China,Ministry of Chemical Industry Based on previous works, this study describes the preparation and stability of silicone rubber dispersion. Stable homogeneous silicone rubber dispersion could be made by dissolving reinforced GY-31 medical grade silicone rubber in 1,1,1-trichloroethane, then pounding in a high speed mill. Thin-walled silicone rubber articles with complex shapes prepared from the dispersion by dipcoating or spraying could satisfy clinical uses. 6 refs.
rat studies which supports a possible link between silicone gel-filled breast implants and autoimmune disorders. Further brief details are given. US,FOOD & DRUG ADMINISTRATION USA
Accession no.489233 Item 359 Plastverarbeiter 44, No.6, June 1993, p.46/50 German EXTRUSION AND CROSSLINKING OF SOLID SILICONE RUBBER Fuchs P This review of silicone rubber extrusion examines plant design and layout, extrusion lines and conditions, mould engineering, vulcanisation systems and conditions, ancillary equipment, profile dies and applications. EUROPEAN COMMUNITY; GERMANY; WESTERN EUROPE
Accession no.488323 Item 360 International Polymer Processing 8, No.2, June 1993, p.178-81 COMPUTER CONTROLLED ROTATIONAL MOULDING OF LIQUID SILICONE POLYMER Teoh S H; Guan K W; Lee N H; Wong Y S; Nee A Y C; Pho R W H Singapore,National University Computers have made it possible to control the thickness of the object accurately. This was made possible by creating an intelligent software which takes in the viscosity and density time variation of the polymer. Using the flat plate withdrawal theory, it computes the new speed for each axis. The relationship between rotational moulding parameters and polymeric material properties for a solvent-silicone rubber system is demonstrated using a hand prosthesis as an example. The time required for gelation of the silicone rubber was about 2 hours. 8 refs. SINGAPORE
Accession no.486519
Item 358 BIBRA Bulletin 32, No.4/5, May/June 1993, p.155 SILICONE MEDICAL DEVICES
Item 361 Journal of Biomedical Materials Research 27, No.7, July 1993, p.867-75 POROUS COLLAGEN SPONGE FOR OESOPHAGEAL REPLACEMENT Natsume T; Ike O; Okada T; Takimoto N; Shimizu Y; Ikada Y Kyoto,University
The FDA is requiring manufacturers to update information on immune-related disorders in the informed consent documents for women receiving breast implants in clinical studies, it is announced. This follows data obtained from
A new artificial oesophagus with a bilayered structure made of porous collagen sponge and silicone was studied. Microscopic observation of tissue reconstruction and epithelial regeneration are presented. 41 refs.
CHINA
Accession no.494209
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JAPAN
Accession no.484268 Item 362 Fire & Flammability Bulletin June 1993, p.7 SILICONE RUBBER DEVELOPMENT PASSES TOUGH SAFETY TESTS Silicone Altimex has developed a low toxicity/low smoke silicone rubber, which will have potential for rubber sealing componentry in the building and transportation markets. The article supplies details of several stringent and comprehensive fire and smoke tests passed by the material. Likely applications include window and door seals in buildings and transportation. SILICONE ALTIMEX EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.484121 Item 363 Revue Generale des Caoutchoucs et Plastiques 70, No.720, Feb.1993, p.58-64 French APPLICATIONS OF SILICONE RUBBERS Schorsch G Rhone-Poulenc SA The structure, properties and applications of polydimethylsiloxane elastomers are examined. 3 refs. EUROPEAN COMMUNITY; FRANCE; WESTERN EUROPE
Accession no.483624 Item 364 Plastverarbeiter 43, No.11, Nov.1992, p.183-5 German AT K ’92: LIQUID SILICONE RUBBER. A HIGHPERFORMANCE MATERIAL FOR THE FUTURE This paper is based on an address given by Dr M. Schulze of Bayer AG. Liquid silicone rubber is the only type of crosslinkable rubber that can be processed in liquid form. Bayer supplies this material as Silopren LSR, a ready-touse, two-component liquid silicone rubber for the injection moulding of small flexible parts and the coating of textile fabrics. BAYER AG EUROPEAN COMMUNITY; GERMANY; WESTERN EUROPE
Accession no.480540 Item 365 Adhesives Age 36, No.5, May 1993, p.26-31 ISO CLASSIFICATION AND REQUIREMENT STANDARD FOR FACADE AND GLAZING JOINT SEALANTS. PART II.
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Wolf A T Dow Corning Corp. This detailed article evaluates ten commercially available silicone construction sealants according to the draft standard of ISO/DIS 11600. Information presented includes an overall assessment summary. The study concludes that ISO/DIS 11600 can be regarded as a step towards international harmonisation of the standards required within the sealant industry. (This article is the second part of an article dealing with ISO Classification and Requirement Standard for Facade and Glazing Joint Sealants; part one of the article appears in Adhesives Age, April 1993). 5 refs. USA
Accession no.480387 Item 366 Biomaterials 14, No.6, May 1993, p.459-64 BIODETERIORATION OF MEDICAL-GRADE SILICONE RUBBER USED FOR VOICE PROSTHESES: A SEM STUDY Neu T R; Van der Mei H C; Busscher H J; Dijk F; Verkerke G J Groningen,University; Netherlands,Biomedical Technology Centre Silicone voice prostheses used for rehabilitation of speech after total laryngectomy are inserted in a non-sterile habitat. Deposits on explanted Groningen Button voice prostheses revealed a biofilm, the result of colonisation of the silicone surface by bacteria and yeasts. Furthermore, it was shown by SEM on sectioned explants that the silicone material was degraded by filamentous and vegetative yeast cells. The different explants showed a variety of sharp-edged, discrete yeast colonies. The yeasts grew just under the silicone surface and up to 700 microns into the silicone material. Nine different types of defect in the silicone material created by the yeasts are described. This degradation of the silicone by yeasts appeared to be the main cause of failure and of the need for frequent replacement of the prostheses. 10 refs. EUROPEAN COMMUNITY; NETHERLANDS; WESTERN EUROPE
Accession no.478732 Item 367 Rubber World 207, No.6, March 1993, p.17/22 SILICONE MAKING AUTOS QUIETER THAN EVER Finney D L GE Silicones Automotive engineers are constantly looking for materials that serve to dampen vibration and hence reduce noise. Silicones have found numerous automotive applications where noise is concerned. Silicone gaskets and bushings
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References and Abstracts
help to reduce noise within the engine, including noise produced by timing chain mechanisms, valves and other enclosed moving engine parts. General Motors’ new Northstar engine incorporates special silicone gaskets to help reduce noise produced by the air and fuel delivery systems. Chrysler is using a special silicone coating system, developed by GE Silicones, as a coating on EPDM weather stripping for windows and doors. USA
Accession no.476856 Item 368 Chemical Marketing Reporter 243, No.17, 26th April 1993, p.SR34 NEW MARKETS Cintron I GE Silicones reports that although growth in Western Europe and the US has slowed, the company has seen double-digit growth for its silicone rubber line in the Asia Pacific region. Overall the US domestic silicones market is estimated at over 300 million pounds, serving the three principal end use sectors of fluids, elastomers and resins. Dow Corning, with a 45% share of the US market, is to double capacity at its plant in Barry, Wales, and has invested in research facilities at its headquarters in Midland, Mich. and Yamakita, Japan. GE Silicones has a new applications development centre in Oyama, Japan. Union Carbide has announced it has finally found a buyer for its silanes business. WORLD
Accession no.476623 Item 369 Multiple Shot, Insert, and Co-Injection Molding. Conference Proceedings. Northbrook, Il., 23rd-24th Oct.1991, p.129-40. 83 INSERT MOULDING WITH SILICONE RUBBER Miller M Lucas Duralith Corp. (SPE,Chicago Section; SPE,Milwaukee Section) This article describes the insert moulding of silicone rubber keypads produced at Lucas Duralith using the liquid injection moulding process. Information is presented on two types of keypad design - diaphragm or pusher-pad - which are used for a majority of the company’s products. The use of the compression process is also briefly mentioned, although the company is said to only use this process for the moulding of silicone rubber stock which is then used to produce conductive ‘pills’ or contacts.
14,No.3,1993,p.184-8 IN VITRO ASSESSMENT OF BACTERIAL ADHESION TO HYDROMER-COATED CEREBROSPINAL FLUID SHUNTS Bridgett M J; Davies M J; Denyer S P; Eldridge P R Nottingham,University; Brighton,University; Nottingham,Queens Medical Centre The adherence of five strains of Staphylococcus epidermis and one strain of S.aureus to both untreated and Hydromer-coated silicone rubber cerebrospinal fluid shunts was studied in vitro using epifluorescent image analysis. The potential of the Hydromer coating in creating biomaterial surfaces which reduce the initial adhesion of bacteria is demonstrated, with a view to reducing the incidence of biomaterial-related infections. The importance of uniformity of coating along the lumen of cerebrospinal fluid shunts is highlighted. 14 refs. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.472417 Item 371 International Polymer Science and Technology 19,No.11,1993,p.T/9-11 NON-HALOGEN-CONTAINING ELASTOMER COMPOSITES OF LOW COMBUSTIBILITY Merkulova T A; Voloshin V N; Mikhlin V E; Kozlova GS It was confirmed that vulcanisates of siloxane polymers with phenyl substituents at the silicon atom are more flame resistant than polymers containing vinyl and methyl substituents. A dependence of the time of extinguishment of specimens on the composition and structure was established. Compositions developed with increased flame propagation resistance, based on SKEP (EPM) and SKEPT (EPDM) and containing aluminium hydroxide, are recommended for introduction in the production of cables for ships, shafts and underground railways. 4 refs.Translation of Kauch.i Rezina,No.3,1992,p.10 RUSSIA
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Item 372 Advances in Pressure Sensitive Adhesive Technology 1. Warwick,RI,1992,p.50-76. 6A1 CHEMISTRY AND TECHNOLOGY OF RADIATION CURABLE SILICONE RELEASE COATINGS Eckberg R P General Electric Co.,Silicones Div. Edited by: Satas D (Satas & Associates)
Item 370 Biomaterials
A brief discussion is presented on the UV- and electron beam curing of silicone release agents followed by an overview of radiation curable silicones. These silicones
USA
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include acrylated silicones, mercapto-vinyl silicone systems and cationic radiation curable silicones. Mention is also made of controlled release additives for silicone systems. 49 refs. USA
type of material, as well as results from the author’s own studies on the use of Polastosil in the construction of car suspensions, are also presented.Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology.
Accession no.469337
EASTERN EUROPE; POLAND
Item 373 Materials News International No.39,1993,p.8-9 BRINGING RELIEF TO OVER ONE MILLION PEOPLE Swanson A B Dow Corning Europe SA Replacement joint implants are described which are made of three grades of Silastic elastomers, and which are used in the treatment of arthritis. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.469318 Item 374 Plastics and Rubber Weekly No.1469,23rd Jan.1993,p.9 THERMOSETS RESTRICTED TO NICHE MARKETS IN THE FUTURE Krauss Maffei has developed a two component injection moulding machine to mould polyester BMC valve covers with integral seals in LSR. KM has developed its new modular machine concept to assist thermoset processors. To change from thermoplastics to thermosets moulding simply involves changing the injection unit and the cards in the control system. A new machine concept was developed and this was based upon three stages of processing. These were the optimised processing of BMC and LSR and the use of a turntable mould. The KM patented AZ unit provides fully automatic material supply. KRAUSS-MAFFEI (UK) LTD. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.468591 Item 375 Polimery Tworzywa Wielkoczasteczkowe 37,No.11-12,1992,p.504-7 Polish UTILISING THE DAMPING CHARACTERISTICS OF SILICONE POLYMERS IN SHOCK-ABSORBING STRUCTURES AND TECHNOLOGY Maciejewski J Warsaw,Industrial Chemistry Research Institute The damping characteristics of Polastosil ABM, a range of siloxane polymers used in shock-absorbing materials, and their main useful properties and potential applications are discussed. The design and the static and dynamic characteristics of a railway buffer constructed using this
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Accession no.467735 Item 376 Polimery Tworzywa Wielkoczasteczkowe 37,No.11-12,1992,p.499-503 Polish SILICONES AS MATERIALS WITH A FUTURE IN POLAND Rosciszewski P; Zielecka M Warsaw,Industrial Chemistry Research Institute A brief review is presented, with reference to published papers and patents, of the history and results of research at the Zoliborz Chemical Institute in the field of synthesis, processing and applications of various organosilicon monomers and polymers. The main commercially developed manufacturing processes and the development of production and application of silicones in Poland are discussed. A table listing the tested and currently manufactured products with their names is given. It is pointed out that there is a considerable delay in the consumption of silicones in Poland in terms of quantity and range as compared with the industrially developed countries. 94 refs.Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. EASTERN EUROPE; POLAND
Accession no.467734 Item 377 Paper, Film & Foil Converter 66,No.10,Oct.1992,p.74/8 SILICONE TECHNOLOGY TAPS PSA MARKET OPPORTUNITIES Handt C M; Kelly D T The use of silicone technology in pressure-sensitive applications is discussed in detail, with special reference to difficult environments, e.g. when adhesives must resist moisture, chemicals and extreme temperatures. DOW CORNING CORP. USA
Accession no.467294 Item 378 PV International Plastics Magazine Oct.1992,p.82/5 HIGH-PERFORMANCE MATERIAL FOR THE FUTURE The production and application of Bayer’s Silopren LSR, is described. The two-component, liquid silicone rubber
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References and Abstracts
is suitable for injection moulding small parts and coating textile fabrics. Applications include protective clothing, electronic applications, automotive applications, medical applications and many others. BAYER AG EUROPEAN COMMUNITY; GERMANY; WESTERN EUROPE
Accession no.467145 Item 379 Macplas International May 1992,p.92-3 FAST CURING FOR OPTICAL FIBRES Dennis W E; Burke D W Dow Corning Corp. The use of UV cured silicone polymers in optic fibre coatings is examined, and advantages over heat cured silicone polymer and UV cured acrylic polymer coatings are described. USA
Accession no.466464 Item 380 Revue Generale des Caoutchoucs et Plastiques 69,No.715,June/July 1992,p.58-62 French SILICONE TECHNOLOGY IN THE SERVICE OF ELECTRONICS Gensler G GE Silicones An examination is made of the thermal and dielectric properties, heat resistance and weathering characteristics of silicone rubbers for use in electronic applications, including coatings, potting compounds, adhesives and transfer moulded components. USA
Accession no.466444 Item 381 Materials Engineering 109,No.9,Sept.1992,p.21-2 SILICONE FOAMS LIGHTEN UP Hartley K R GE Silicones Silicone elastomer foams are reviewed. Their processability, performance, properties and applications are discussed in some depth, with particular emphasis on their stability, fire retardance properties and lower smoke generation and toxicity than organic foams. USA
Accession no.465884 Item 382 High Performance Textiles Oct.1992,p.4-5
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YARN COATING TECHNIQUE Cogent Ltd. of London, has developed a treatment in which a cord or strand can be coated with a dilute solution of a polysiloxane prepolymer which is then pre-cured insitu to create a protective sheath around the yarn encapsulating it. The article supplies comprehensive details of the process which is seen as having special relevance to the production of improved dental floss. (US patent number 5 021 267). COGENT LTD. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.465845 Item 383 142nd Meeting,Fall 1992,Conference Proceedings. Nashville,Tn.,3rd-6th Nov.1992,Paper 93,pp.24. 012 COMPRESSION STRESS RELAXATION. II. AN IMPROVEMENT OVER TRADITIONAL TESTS FOR THE EVALUATION OF SEALANT MATERIALS Bunting W; Slocum G H; Russell W D GE Silicones (ACS,Rubber Div.) A compression stress relaxation test method consistent with ISO 3384 for the evaluation of rubber sealing materials is described. The test measures important material performance characteristics not measured by traditional test methods. A comparison of compression stress relaxation test results with compression set, volume per cent swell, oil immersion and heat ageing is made using heat cured silicone rubber and acrylic elastomer oil pan gasket materials. 2 refs. USA
Accession no.465622 Item 384 Journal of Biomedical Materials Research 26,No.8,Aug.1992,p.979-87 SHORT-TERM RESPONSE OF BRAIN TISSUE TO CEREBROSPINAL FLUID SHUNTS IN VIVO AND IN VITRO Del Bigio M R; Fedoroff S Manitoba,University; Saskatchewan,University The results are reported of a study carried out to determine how gross physical characteristics of cerebrospinal fluid shunts and the cellular proliferative response to shunts contribute to shunt obstruction. The shunt tubing employed was made of barium-impregnated, silverimpregnated or unimpregnated silicone rubber. Contact between the shunt catheter and vascularised brain tissue was found to be the most important factor in the genesis of shunt obstruction. 21 refs. CANADA
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Item 385 Composites Plastiques Renforces Fibres de Verre Textile 32,No.3,May/June 1992,p.376-80 MANUFACTURING A VALVE COVER WITH SEAL IN ONE WORK STAGE Schultheis S M KRAUSS-MAFFEI AG Details are given of an injection moulding machine with which it is possible to produce an automotive valve cover in glass fibre-reinforced unsaturated polyester BMC together with its seal of liquid silicone rubber in one cycle. The manufacturing costs for this process are compared with those for the traditional two-stage operation. GERMANY
Accession no.462092 Item 386 Plastverarbeiter 43,No.5,May 1992,p.126/9 German IMAGE PROCESSING SYSTEM FOR THE AUTOMATIC TESTING OF SILICONE RINGS A South German company has developed an automatic, optoelectronic testing system whose possibilities include the a testing of silicone rings for various types of defect. The system has been designed in such a way that it requires no subsequent development or modification, and can be readily adapted both to the actual parts produced and to the user’s testing requirements. The entire system, including testing process, operation of the system and its capabilities, is described. WIDMANN BILDVERARBEITUNGSSYSTEME OHG GERMANY
Accession no.462057 Item 387 Rubber and Plastics News 2 3,No.17,15th June 1992,p.4 DOW CORNING OFFERINGS STRESS CUSTOMER SUPPORT Dow Corning has introduced a range of marked silicone tubing, and a range of silicone materials for medical applications. Dow works with its customers to make materials for specific applications. In particular, details are given of Silastic Rx marked tubing, made from 50 durometer, medical grade silicone elastomer. Also mentioned is a series of silicone urethane copolymers, a clear adhesive gel technology, a silicone elastomer foam, two-part liquid silicone rubbers, and technology for a onepart formulation of optically clear, medical-grade elastomers. DOW CORNING CORP. USA
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Item 388 Polimeri 13,Supplement 1,1992,p.35-8 Serbo-Croatian SILICON INSULATORS Mardesic O;Tisov J;Zelic N Previously reported data on silicone insulators are reviewed. The properties of insulators made from silicone and ceramics are compared and end-use applications indicated. 9 refs. EASTERN EUROPE; YUGOSLAVIA
Accession no.461007 Item 389 Journal of Applied Biomaterials 3,No.3,Fall 1992,p.239-42. CLINICAL REVIEWS: MAMMARY IMPLANTS Kossovsky N;Papasian N CALIFORNIA,UNIVERSITY AT LOS ANGELES The use of silicone rubbers and PU foams in mammary implants is reviewed with reference to aspects of bioreactivity, degradation and carcinogenicity. 38 refs. USA
Accession no.460974 Item 390 Materiaux & Techniques 80,No.1-2-3,1992,p.51-4 French SOLVENTLESS SILICONE COATING MATERIAL FOR SURFACE MOUNTED ELECTRONIC COMPONENTS Piazza J;Dinallo A J GE SILICONES The use of solventless silicone encapsulating materials for surface mounted electronic components is discussed with reference to those developed by GE Silicones. Details are given of their properties, applications and methods of polymerisation. USA
Accession no.459670 Item 391 Machine Design 64,No.14,9th July 1992,p.52-3 MINERAL-REINFORCED SILICONES TAKE THE HEAT Dinallo J GE SILICONES The features and end-use applications of mineral-filled silicone polymers, which can be used as replacements for metals and injection moulded to produce components withstanding operating temps. as high as 275C continuously, are described. Applications include encapsulation for
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References and Abstracts
electronic devices, automotive components and domestic appliances. Fillers employed are generally fused amorphous silica and a small amount of E-glass. USA
Accession no.459325 Item 392 Industria della Gomma 36,No.4,April 1992,p.35-8 Italian SILICONE RUBBER IN THE AUTOMOTIVE INDUSTRY Bourrain P RHONE-POULENC SA
Item 395 Adesione 3,No.1,Jan/Feb.1992,p.10-5 SILICONE MASTICS IN THE BUILDING INDUSTRY Houde M RHONE-POULENC SA
The use of silicone rubbers in automotive components is discussed, and the properties and applications of materials produced by Rhone-Poulenc are described. These include Rhodorsil heat curing and Rhodorseal room temperature curing silicone rubbers. Applications examined in particular detail include seals, spark plug boots, ignition cables, coolant and heater hoses and oil pan gaskets. 2 refs.
(In Italian, English and French). The use of silicone mastics in the building industry is reviewed. Different silicone mastic formulations and their properties are discussed, and weathering tests are described. Many types of silicone sealants are now available. All have different properties to suit specific requirements, but all are weatherproof. Durability combined with elasticity, adhesion to the substrate and chemical resistance account for the increasing use of silicone sealants in the building industry. Special reference is made to the ‘Vitrage Exterieure Colle’ building technique in which glass elements are bonded and sealants have to maintain their adhesion properties, long-term, under all weather conditions.
EUROPEAN COMMUNITY; FRANCE; WESTERN EUROPE
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Item 393 Revue Generale des Caoutchoucs et Plastiques 69,No.714,May 1992,p.64-6. French THINK VACUUM CASTING Cottineau F MCP EQUIPMENT An account is given of the MCP process for vacuum casting prototypes in two-component resins using silicone rubber moulds. EUROPEAN COMMUNITY; FRANCE; WESTERN EUROPE
Accession no.457572 Item 394 Adesione 3,No.1,Jan/Feb.1992,p.16-24 NEW APPLICATIONS OF SILICONES IN THE BUILDING INDUSTRY Musci G GENERAL ELECTRIC CO. (In Italian, English and French). The chemistry, molecular structure and main physical and chemical properties of silicones are outlined. New applications of silicones in the building industry are discussed, including structural glazing, flame retardant barriers, roofing systems and as an opaquing agent for reflective glass. Detailed comparative results are given for accelerated ageing tests and weather resistance of silicone, PU, butyl elastomer, neoprene + chlorosulphonated PE, chlorosulphonated PE and vinyl elastomer.
Item 396 International Polymer Science and Technology 19,No.2,1992,p.T/33-40 VULCANISATION OF SILICONE RUBBERS Schaetz M A review of silicone rubber vulcanisation since the 1950s is given with emphasis on reaction mechanisms and side reactions. Methods considered are peroxide vulcanisation, radiation vulcanisation, hydrosilylation reactions and condensation vulcanisation of functional groups by reactive crosslinking agents. Applications, e.g. adhesives and sealants, and specific advantages of each technique are pointed out. 34 refs. (Full translation of Plasty a Kaucuk,No.1,1991,p.5). CZECHOSLOVAKIA; EASTERN EUROPE
Accession no.456643 Item 397 Contraception 45,No.5,May 1992,p.453-61 ACCEPTABILITY OF NORPLANT-2 RODS AS A METHOD OF FAMILY PLANNING Singh K;Viegas O A C;Ratner S S SINGAPORE,NATIONAL UNIVERSITY HOSPITAL Details are given of a five-year contraceptive study using the Norplant-2 rod system which consisted of two PDMS rods in which levonorgestrel was incorporated. 5 refs.
EUROPEAN COMMUNITY; ITALY; WESTERN EUROPE
SINGAPORE
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Item 398 Biomaterials 13,No.5,1992,p.333-6 DIMENSIONAL STABILITY OF CONDENSATION SILICONE RUBBERS Braden M LONDON,UNIVERSITY Linear shrinkage during 24h after setting of a number of proprietary condensation silicone dental impression materials was studied. Weight loss and change in volume were measured over the same time period by weighing similar specimens in air and water. It was concluded that the linear shrinkage of condensation silicone rubbers is, to a first approximation, predictable from the mass of volatile products lost, with the exception of the highly filled putty materials. In the latter case the measured changes are much larger than those predicted theoretically; this may be a consequence of strains built in during moulding of specimens. 5 refs. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.454392 Item 399 Journal of Biomedical Materials Research 26,No.5,May 1992,p.631-50 DIFFERENCE IN TUMOUR INCIDENCE AND OTHER TISSUE RESPONSES TO POLYETHERURETHANES AND POLYDIMETHYLSILOXANE IN LONG-TERM SUBCUTANEOUS IMPLANTATION INTO RATS Nakamura A;Kawasaki Y;Takada K;Aida Y;Kurokama Y;Kojima S;Shintani H;Matsui;Nohmi T;Matsuoka A;Sofuni T;Kurihara M;Mitaya N JAPAN,NATIONAL INST.OF HYGIENIC SCIENCES; JAPAN,PUBLIC WELFARE INST.OF SCIENTIFIC RESEARCH The long-term (1- and 2-year) adverse tissue responses including tumour formation by subcutaneous implantation of PU and silicone films into rats were compared. Tissue responses around implants were classified into four groups: (a) tumour, (b) atypical cell proliferation accompanied by preneoplastic changes, (c) cell proliferation without preneoplastic changes, (d) no obvious responses. In both implantation periods, the PUs gave higher incidents of adverse responses including tumour formation in comparison to silicone. 29 refs. JAPAN
Accession no.453090 Item 400 Plastics Technology 38,No.5,May 1992,p.78-80 NEW PLASTICS FOR ELECTRONICS GE Plastics has expanded its Supec PPS line with the introduction of high ductility and low-flash grades for
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surface mount technology and high-performance connectors. GE Silicones has introduced two new silicone moulding compounds for electronics and electronics packing. Hercules has unveiled a brand new resin chemistry, Sycar silicon-carbon thermosets. They are currently available in neat resin grade for multilayer circuit boards and a formulated liquid resin for potting and encapsulating. GE PLASTICS; GE SILICONES; HERCULES INC. USA
Accession no.452191 Item 401 Advances in Polymer Technology 11,No.2,Summer 1991/92,p.133-40 INITIATION OF A SOLID-STATE EXTRUSION OF A CROSSLINKED SILICONE RUBBER Cohen A;Burmester A F DOW CHEMICAL CO. The initiation stage of a plunger-driven extrusion of a crosslinked silicone rubber material was investigated. The experiments were performed at room temp. with a series of capillaries of various diameters positioned in a conventional Instron rheometer. It was observed that the extrusion of the rubber started with a cylindrically shaped ‘plug’ which was followed by an ‘apple peel’ shape. This change in the shape of extrudates corresponded to changes in the load applied to the plunger. Analysis of this transition and its variation with the size of the capillary indicated that interesting physical mechanisms were involved in this solid-phase processing operation. 14 refs. USA
Accession no.451474 Item 402 Journal of Microencapsulation 9,No.2,April-June 1992,p.183-6 MICROENCAPSULATION OF MENADIONE SODIUM BISULPHITE WITH PDMS BY THE SPRAY-DRYING PROCESS. CHARACTERISATION BY THERMAL ANALYSIS Gronchi P;Del Rosso R;Centola P;Cosentino R F MILANO,POLITECNICO Menadione sodium bisulphite was microencapsulated with a PDMS membrane using spray-drying technology. Products were characterised by DTA and chemical and physical methods. 6 refs. EUROPEAN COMMUNITY; ITALY; WESTERN EUROPE
Accession no.451328 Item 403 Analytical Chemistry 64,No.5.1st March 1992,p.347/56 PRESERVING OUR HERITAGE IN STONE
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References and Abstracts
Wheeler G S;Schein A;Shearer G;Su S H;Blackwell C S IOWA,UNIVERSITY; NEW YORK,METROPOLITAN MUSEUM OF ART; SCIENCE & TECHNOLOGY COMMUNICATIONS; UNION CARBIDE CORP. Developments in stone consolidation techniques for use in art conservation are discussed with particular reference to the use of alkoxysilane monomers or oligomers to form crosslinked silicate polymers within the matrix of stone objects. 14 refs. USA
Accession no.450279 Item 404 Plastics and Rubber Weekly No.1438,6th June 1992,p.8 GE UNVEILS EUROPEAN FUTURE Silicones are reported to be some of the most versatile rubber materials on the market, capable of resisting many chemicals and solvents as well as operating over a wide temperature range. GE Silicones currently turns over approximately 650 million US dollars/yr. in these materials; some of the key developments that the company sees as being important in the future are outlined. GE SILICONES EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.450048 Item 405 Macplas 17,No.135,Jan/Feb.1992,p.68-9 Italian LIQUID SILICONES A system developed by Ubalit for liquid silicone rubber processing uses MIR injection moulding machines and precision moulds produced by the Multicadd computer aided design and manufacturing system. Some applications of the process are described. FIAT SPA; MICROSYSTEM; MIR SPA; UBALIT EUROPEAN COMMUNITY; ITALY; WESTERN EUROPE
Accession no.448074 Item 406 Journal of Macromolecular Science A 28,No.11-12,Nov/Dec.1991,p.1151-76 SYNTHESIS AND CHARACTERISATION OF POLYSILANES Matyjaszewski K;Cypryk M;Frey H;Hrkach J;Kwan Kyu Kim;Moeller M; Ruehl K;White M CARNEGIE-MELLON UNIVERSITY The various methods of synthesis of polysilanes are reviewed aimed at improving control of the polymer structure and other properties in copolysilanes of various
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composition. Particular attention is paid to sonochemical reductive coupling, ring-opening polymerisation, modification of polymethylphenylsilylene and solid-state transitions in copolysilanes. 47 refs. USA
Accession no.446966 Item 407 Progress in Rubber and Plastics Technology 7,No.4,1991,p.308-24 SILICONE ELASTOMERS. TOXICOLOGICAL AND OTHER SAFETY ASPECTS Cassidy S L DOW CORNING LTD. The safety profile of silicone elastomers is reviewed, with emphasis on major areas of potential hazard, including toxicity, biodurability, behaviour in fire and elevated temp., chemical migrants and contaminants, and food contact and biomedical applications. It is shown that silicone elastomers exhibit significantly more benign characteristics than other competing elastomers offered for the same end-use applications. 63 refs. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.446907 Item 408 Gummi Fasern Kunststoffe 45,No.2,Feb.1992,p.76-8 German NEW SEALANTS BASED ON SILANEMODIFIED POLYMERS Probster M TEROSON GMBH (Paper given at Eurobond 1991 in Wiesbaden). Sealants formed from polyoxypropylene diol with silyl end-groups show a high rate of cure, have good UV resistance and will take paint readily. The properties of a number of such sealants are described and examples of their application are given. GERMANY
Accession no.443327 Item 409 Plastics Design Forum 17,No.1,Jan/Feb.1992,p.16 SILICONE ELASTOMER IMPLANTS HELP RELIEVE ARTHRITIC PAIN Dow Corning is reported to have led development for 20 years in small-bone orthopaedic implants produced from medical grade silicones. Now, flexible finger, wrist and toe implants made from the company’s Silastic 100 high performance silicone elastomer also include titanium shields or grommets. These are claimed to help prevent damage to the implants from rough bone edges. Details are given.
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References and Abstracts
DOW CORNING CORP.; DOW CORNING WRIGHT; TAMCENAN INC. USA
Accession no.443172 Item 410 Advanced Composites Engineering Feb.1992,p.10-1 IT’S IN THE BAG Cooke M AEROVAC SYSTEMS (KEIGHLEY) LTD. Vacuum bugging is reported to be a widely-used technique for moulding advanced composite components. The technique has conventionally been achieved using a high temperature, heat stabilised nylon film as the membrane. The advantages and disadvantages of re-usable silicone rubber vacuum bags compared to disposable nylon ones are discussed in detail. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.442996 Item 411 European Rubber Journal 174,No.3,March 1992,p.16 SILICONE FEMRING SEEKS D H OK Bebbington S It is reported that women in UK may be the first to have a new long term contraceptive device; the manufacturer, Roussel Laboratories, is waiting for the Department of Health to licence the silicone rubber intra-vaginal ring which emits contraceptive hormones. Details are given. ROUSSEL LABORATORIES; SILICONE DEVELOPMENTS LTD.; UK,DEPT.OF HEALTH; WORLD HEALTH ORGANISATION EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.442133 Item 412 Elastomerics 124,No.1,Jan.1992,p.23-4 SILICONE GASKETS INSTALLED IN RACE CARS TAKE DRIVERS ACROSS THE FINISH LINE Select-Sil moulded valve covers and oil pan gaskets from Freudenberg-NOK General Partnership are demonstrated to be able to keep automotive engines leak-free at temperatures as high as 500F. They are used in the Chevrolet cars and light trucks, and have performed in the Chevrolet Corvette which won the SCCA World Challenge Series Team championship. The silicone gaskets are re-usable and have shown great durability and reliability. FREUDENBERG-NOK GENERAL PARTNERSHIP USA
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Item 413 Elastomerics 124,No.1,Jan.1992,p.10-3 SILICONE HOSES WITHSTAND HIGH HEAT IN TURBOCHARGED CLASS 8 TRUCK ENGINES Bayne D;Romanowski R;Arthur M DOW CORNING CORP.; GATES RUBBER CO. Due to recent changes in EPA emissions standards, truck manufacturers have been encouraged to use turbocharged engines to improve fuel economy and reduce output emissions. Higher operating temperatures have in turn led to the design of alternative cooling methods for the charged air to improve fuel efficiency. Air to air methods of cooling are described and the market which has opened up for hose materials which will withstand the high heat environment over long periods of time without significant degradation. Silicone rubber and the new generation of silicones which retain plasticity are evaluated. USA
Accession no.441193 Item 414 Rubber World 204,No.6,Sept.1991,p.14-5 LIQUID SILICONES - TAKE TWO Menough T Information is presented in some detail on liquid silicone rubber systems (LSR), how they come to be commercialised and how Liquid Silicone Molding Laboratories (LSM Labs.) became established. Advantages of these systems over conventional gum rubbers, details of how to injection mould LSR and potential problems are also discussed. LIQUID SILICONE MOLDING LABORATORIES USA
Accession no.434455 Item 415 Adhesion.Principles and Practice for Coatings and Polymer Scientists.Conference Proceedings. Kent,Oh.,20th-24th May 1991,Paper 10. 9(12)4 COUPLING AGENTS AS ADHESION PROMOTERS IN ADHESIVE BONDING Boerio F J;Dillingham R G;Ondrus D J CINCINNATI,UNIVERSITY Edited by: Krauss C J (Kent State University) The characteristics of silane primer films applied to metals and the use of silane primers to enhance the hydrothermal stability of adhesive bonds to metal are presented. Emphasis is given to iron/epoxy adhesive joints, titanium/epoxy adhesive joints, aluminium/epoxy adhesive bonds, rubber to metal bonding, adhesion of PE to sapphire. 38 refs. USA
Accession no.430273
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References and Abstracts
Item 416 137th Meeting Spring 1990.Conference Preprints. Las Vegas,Nv.,29th May-1st June 1990,Paper 14. 012 SILICONES IN MEDICAL MARKETS - PAST, PRESENT AND FUTURE Brodhagen T W DOW CORNING CORP. (ACS,Rubber Div.)
Permeability coefficients decreased slightly with increasing pressure difference, but increased with increasing temp., the activation energies being from 1.4 to 4.3 kcal/mol. Permeability coefficients decreased with increasing bulkiness of functional groups and decreased considerably when Si-O bonds were replaced by Si-C bonds. Relevance to gas separation is suggested. 12 refs.
A review is presented of the historic progression of the use of elastomeric silicones in medical and pharmaceutical product markets in the USA. Information is included of the testing of the biocompatibility of materials, process controls for the manufacture of these materials, and regulatory implications for their use in device applications. 6 refs.
USA
USA
Accession no.430144 Item 417 Materials News International No.37,p.6 SILICONE ENCAPSULANT RESISTS CORROSIVE SPACE HAZARD DOW CORNING CORP. The structure of the Hubble Space Telescope’s solar array panel, with its 48, 760 silicon solar cells, and its deployment in space are described. For the flexible blankets of the solar generator to survive the harsh environment of an orbit 600km above the earth for five years, a special multi-laminate compound was developed. Its structure is described and illustrated. The silver mesh used for power transfer is surrounded by a symmetrical sandwich of silicone adhesive, Kapton and glass-fibre filled with Dow Corning’s space grade encapsulant. The properties of this encapsulant are listed and other space applications of it are given. EUROPEAN COMMUNITY; UK; USA; WESTERN EUROPE
Accession no.425031 Item 418 Journal of Applied Polymer Science 42,No.9,5th May 1991,p.2397-403 PERMEABILITY OF SILICONE POLYMERS TO HYDROGEN Bhide B D;Stern S A SYRACUSE UNIVERSITY Permeability coefficients for hydrogen in ten different types of silicone polymer membranes were measured in the temp. range 10C to 55C and at pressures up to about 6.8 atm. Polymers were polydimethyl siloxane, polyethylmethyl siloxane, polymethylpropyl siloxane, polymethyloctyl siloxane, polymethyltrifluoropropyl siloxane, polymethylphenyl siloxane, polydimethyl silmethylene, polysilethylene siloxane, polysilhexylene siloxane and poly-m-silphenylene siloxane.
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Accession no.424146 Item 419 Journal of Applied Polymer Science 42,No.2,20th Jan.1991,p.383-9 PERMEATION OF DISSOLVED CARBON DIOXIDE IN SYNTHETIC MEMBRANES Nakagawa T;Naruse A;Higuchi A MEIJI,UNIVERSITY Permeability coefficients of dissolved carbon dioxide in polydimethyl siloxane, oxygen plasma-treated polydimethyl siloxane, PS, LDPE and polyamide-6 membranes were studied by applying a carbon dioxide electrode in a liquid to liquid diffusion cell. Boundary layer resistance was estimated for the plasma-treated and non-treated polydimethyl siloxane. Plasma treatment, which made the surfaces hydrophilic without changing polymer bulk properties, decreased the boundary layer’s thickness and increased the apparent permeability coefficient in the liquid phase. 18 refs. JAPAN
Accession no.418477 Item 420 Integration of Fundamental Polymer Science and Technology. Barking,Elsevier Science Publishers,1989,p.308-12. 012 CONFORMATIONAL DISORDER IN POLYDIETHYLSILOXANE (PDES) Kogler G;Loufakis K;Bahnert R;Moller M FREIBURG,INSTITUT FUR MAKROMOLEKULARE CHEMIE Edited by: Lemstra P J;Kleintjens L A (Eindhoven,University of Technology; DSM Research BV) DSC, solid state NMR, optical microscopy and rheological measurements were used to examine the phase diagram of polydiethylsiloxane. The mobility of the chains in the different phases was investigated. Changes that occurred upon shearing and the influence of quenching are discussed. 6 refs. EUROPEAN COMMUNITY; WEST GERMANY; WESTERN EUROPE
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Item 421 43rd Annual Conference and Focus ’88;Proceedings. Cincinnati,Ohio,1st-5th Feb.1988,Session 24-B,pp.4. 627 BONDING TO PLASTIC SURFACES THROUGH SILANE PRIMERS AT MODERATE TEMPERATURES Plueddemann E P DOW CORNING CORP. (SPI,Reinforced Plastics/Composites Institute) Silane primers have been developed that will give water resistant bonds of virtually all thermoplastics to metals or silaceous surfaces if the polymer is fused against the primed surfaces. The same primers may be effective in bonding a lower-melting polymer in its fused state against another primed higher melting polymer. In some circumstances adhesion between polymers is desired where fabrication conditions are limited to room temperature or only mildly elevated temperatures. A partially hydrolysed vinylbenzyl cationic silane (Z6032) was especially effective on oriented polyethylene fibres. A new silane modified melamine resin was especially effective in bonding urethanes to engineering thermoplastics either as a primer or as an additive to the urethanes. 7 refs. USA
Accession no.414880 Item 422 Adhasion 34,No.11,Nov.1990,p.32/5 German ECONOMIC JOINTING WITH SILICONE RUBBER Engelmann H PCI POLYCHEMIE A description is given of the uses and advantages of silicone rubber sealants in the building industry. GERMANY
Accession no.411463 Item 423 Revue Generale des Caoutchoucs et Plastiques 67,No.696,May 1990,p.224-5 French ADHESIVE AND NON-ADHESIVE BEHAVIOUR OF SILICONE COMPOSITIONS Schorsch G RHONE-POULENC SA The nature of silicone polymers is discussed and examples of adhesive and non-adhesive behaviour given. The dichotomy is further elaborated under three headings: (a) the behaviour of a dimethylsilicone chain on a solid surface, (b) the properties of RTV silicones and (c) the properties of accelerated RTV silicones, recently introduced for silicone coatings. EUROPEAN COMMUNITY; FRANCE; WESTERN EUROPE
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Item 424 Materiale Plastice 27,No.1,Jan/March 1990,p.50-3 Rumanian SILICONE RUBBERS. I. CONTRIBUTIONS TO SILICONE RUBBER SYNTHESIS BY HOT VULCANISATION Marcu M;Stiubianu G;Lazarescu S E;Streba E;Stanciu A INSTITUTUL DE CHIMIE MACROMOLECULARA PETRU PONI A review is presented of results on the synthesis of hot vulcanised silicone rubbers. The anionic and cationic polymerisation, compounding and vulcanisation of the rubbers are discussed. 22 refs. EASTERN EUROPE; RUMANIA
Accession no.408497 Item 425 Handbook of Elastomers. New York,Marcel Dekker Inc.,1988,p.551-615. 011 ADVANCES IN SILICONE RUBBER TECHNOLOGY Polmanteer K E KEP ENTERPRISES Edited by: Bhowmick A K;Stephens H L 34 refs. USA
Accession no.406504 Item 426 Advanced Materials 2,No.9,Sept.1990,p.398-404 CERAMICS FROM ORGANOMETALLIC POLYMERS Peuckert M;Vaahs T;Brueck M HOECHST AG This review of non-oxide ceramics concentrates mainly on the preparation and properties of silicon preceramic polymers. Silicon carbide and silicon nitride precursors are discussed in detail. Pyrolysis converts the polymers into the ceramic state. The inorganic polymers can be liquefied and are soluble, which offers advantages over ceramic powder or metallurgical processing and gives rise to many novel applications such as ceramic coatings, binders, impregnations or spun fibres. 70 refs. HOECHST AG; NIPPON CARBON CO.; UBE INDUSTRIES LTD. EUROPEAN COMMUNITY; WEST GERMANY; WESTERN EUROPE
Accession no.406448 Item 427 Rubber World 202,No.3,June 1990,p.33-7
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References and Abstracts
SILICONE USAGE EXPANDING IN EUROPEAN AUTOMOTIVE APPLICATIONS Finney D GENERAL ELECTRIC CO.,SILICONES DIV. The versatility of silicone chemistry, couple with the reliability, safety and superior performance of these inorganic materials is cited for their ability to penetrate approximately 40 applications on the average US automobile. A number of present and potential automotive applications are described particularly in engine hot spots. USA
Accession no.404022 Item 428 Journal of Materials Science 25,No.6,June 1990,p.3017-23 GAS-INDUCED DAMAGE IN ELASTOMERIC COMPOSITES Briscoe B J;Zakaria S LONDON,UNIVERSITY,IMPERIAL COLLEGE Damage in elastomers caused by gases escaping from the polymer matrix was studied using transparent silicone elastomer (Sylgard 184) filled with low concentrations of glass spheres that had been given various surface treatments to improve or reduce polymer-filler interaction. Optical microscopy techniques were developed to examine the internal cracks found during a typical gasinduced rupture cycle. Stress-strain data indicated that the filler particles significantly modified the stress fields in the elastomer during gas-induced rupture. Use of dynamic mechanical properties as a guide to the extent of damage is discussed. 18 refs.
SILICONE SEALANTS AND ADHESIVES FOR AEROSPACE/DEFENCE APPLICATIONS Baile M;Fuson S E DOW CORNING CORP. (Adhesive & Sealant Council) A review of the properties and use of silicone sealants and adhesives for the aerospace industry is presented. It includes fluorosilicone sealants, sealants for munition casings, sealants for missiles and aircraft fairing. Silicone interlayer adhesives for the bonding of substrates used in canopies and periscopes are also included as well as general purpose silicone sealants and adhesives which can be tailored to requirements. Properties of some products are shown. USA
Accession no.399401 Item 431 3,no.3,1990,p.31/1-31/91 SILICONE RUBBERS Trego B R;Winnan H W DOW CORNING LTD.; RAPRA TECHNOLOGY LTD. Rapra Review Report No.31 A review is presented on silicone rubbers covering basic formulation and cure chemistry, properties, processing methods and applications. A literature search from the Rapra database on silicone rubbers is included giving references and abstracts from relevant documents relating to the report with a subject index. 471 refs. EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.398996
EUROPEAN COMMUNITY; UK; WESTERN EUROPE
Accession no.403669 Item 429 Tech XIII.Proceedings of the Pressure Sensitive Tape Council’s Thirteenth Annual Technical Seminar. Itasca,Il.,2nd-4th May 1990,p.155-58. 6A1 ADHESIVE/SILICONE INTERFACE Jones J D DOW CORNING CORP. (Pressure Sensitive Tape Council) The interfacial phenomena which occur between the pressure sensitive adhesive layer and the release coating are described, together with possible solutions to the problems which occur. USA
Accession no.402481
Item 432 Rubber and Plastics News 18,No.22,15th May 1989,p.12 FDA STUDYING SILICONE RUBBER CONTRACEPTIVE Moore M An advisory committee to the FDA is urging the Administration to approve the use of Norplant. Said to be as effective as birth control pills and safer to use, Norplant consists of six silicone rubber capsules containing levonorgestrel. When implanted under the skin the capsules provide a woman with a constant miniscule dose of hormone for up to 5 years. According to the Population Council, the hormone inhibits ovulation and prevents sperm from entering the uterus. Results of tests on 2,470 women are reported. USA
Item 430 Meeting Technical & Business Challenges in Specialised Markets.Proceedings of the ACS Fall 1989 seminar. Rosemont,Il.,22nd-25th Oct.1989,p.141-52. 6A1
© Copyright 2001Rapra Technology Limited
Accession no.381471 Item 433 Rubber and Plastics News 18,No.24,12th June 1989,p.36-41
147
References and Abstracts
EFFECT OF CROSSLINK STRUCTURE ON PDMS Halladay J R LORD CORP. This detailed review describes studies which examine the effect of network crosslink distribution on the elastomeric properties of polymethylsiloxane (PDMS). From the work by J.E.Mark, the term ‘bimodal networks’ has become popular, which indicates the crosslinking of long polymer chains with a large mole fraction of short polymer chains. The majority of data published has focused on the elucidation of molecular aspects of rubber elasticity, and have begun to associate increased tear and tensile strength with the use of bimodal distribution of polymer chains, since silicone elastomers are not noted for being overendowed with either of these two properties. 17 refs. USA
Accession no.380899 Item 434 Handbook of Pressure Sensitive Adhesive Technology.2nd edn.. New York,1989,p.601-26. 6A1 SILICONE RELEASE COATINGS Jones J D;Peters Y A DOW CORNING CORP. Edited by: Satas D (Satas & Associates) Silicone release coatings are used for bar code labels, product labels, price tags, care and warning labels, name tags, display banners, bumper stickers, packaging tapes, self adhesive wall coverings, floor and carpet tiles and transfer tapes. Consideration is given to physical properties, chemistry, types of coating, solvent-borne release coatings, water-borne systems, solventless silicone coatings, radiation curable release coatings, coating evaluation. 12 refs. USA
Accession no.375985 Item 435 Handbook of Pressure Sensitive Adhesive Technology.2nd edn.. New York,1989,p.508-17. 6A1 SILICONE PRESSURE SENSITIVE ADHESIVES Sohieski L A;Tangney T J DOW CORNING CORP. Edited by: Satas D (Satas & Associates) The adhesives are based on a polymer or gum and a tackifying resin. High molecular weight polydimethyl siloxane or polydimethyldiphenyl siloxane containing residual silanol functionality (SiOH) on polymer chain ends. The resin is a three dimensional silicate structure that is endcapped with trimethylolsiloxy groups (OSiMe3).
148
Polycondensation results in a rheologically suitable material. Cure chemistry after solvent evaporation is described. The use of primers to obtain adhesion to some tape backing materials is discussed. Typical properties, industrial and medical applications are mentioned. 11 refs. USA
Accession no.375952 Item 436 Journal of Coated Fabrics 17,April 1988,p.279-87 NEW SILICONE FOAM ENHANCES HIGHPERFORMANCE FABRICS Hartley K R GENERAL ELECTRIC CO.,SILICONE PRODUCTS DIV. Details are given of RTF-762 silicone foam for highperformance fabric applications requiring silicone properties and light weight. The compound features a proprietary formulation which is claimed to provide a level of mechanical strength not previously attainable with foamed RTV materials. USA
Accession no.372775 Item 437 Adhesives,Sealants,and Coatings for Space and Harsh Environments.Conference Proceedings. Denver,Colorado,7-9 April 1987,p.281-91. 63Tr.Sp. DURABILITY OF SILICONE SEALANTS Owen M J;Klosowski J M DOW CORNING CORP. (ACS,Div.of Polymeric Materials Science & Engng.) The environmental durability of silicone sealants is reviewed, particular emphasis being placed on PDMS but with reference to polyphenylmethylsiloxanes and the fluorosilicone, polytrifluoropropylmethylsiloxanes. Responses to various environmental stresses, including those associated with weathering, such as ozone and temperature extremes, as well as electrical stresses, such as corona discharge, are discussed. This behaviour is related to the surface and bulk properties of silicones and particularly to the low intermolecular forces and high chain flexibility of the polymer molecules. 27 refs. USA
Accession no.364141 Item 438 European Adhesives & Sealants 5,No.3,Sept.1988,p.3/6 BEWARE THE ACETOXY Woolman R ADSHEAD RATCLIFFE & CO.LTD. A review is presented of the many types of silicone sealants available, their properties, applications and
© Copyright 2001 Rapra Technology Limited
References and Abstracts
method of cure. The need for careful selection of the correct sealant type for a particular application, especially with regard to volatile products evolved during the curing process, is emphasised. Particular reference is made to silicones using acetoxy cure systems. Their irritant factor and corrosive effect on concrete and metals is outlined. UK
Accession no.360590 Item 439 Synthetic Adhesives and Sealants, Chichester, John Wiley & Sons, 1987, p.89-111. 6A1 SILICONE ADHESIVES, SEALANTS AND COUPLING AGENTS Wake W C CITY UNIVERSITY,LONDON Edited by: Wake W C A detailed review is given with particular reference to chemical rather than physical and engineering aspects of joints involving silicone polymers and other siliconecontaining compounds. It includes synthesis of monomers and preparation of polymers, synthesis of silane coupling agents, crosslinking, primers for silicone adhesives, use of fine particle fillers in silicone adhesives and sealants, and durability of silicone adhesives and sealants. 46 refs. UK
Accession no.359907 Item 440 Revue Generale des Caoutchoucs et Plastiques 65,No.676,March 1988,p.105-10 French ADHESION OF SILICONE ELASTOMERS: DEVELOPMENT OF AN ON-LINE METHOD Barquins M;Pouchelon A CNRS,LABORATOIRE DE MECANIQUE DES SURFACES; RHONE-POULENC SA The adhesion and peel characteristics of viscoelastic materials are discussed as an introduction to the development of equipment for the continuous monitoring of the effects of incorporating compounding ingredients. Tests were carried out on silicone rubber sheet formed several days beforehand on a calender. The test machine can also be used to characterise the tack of thin adhesive films especially with respect to stick-slip effects. 16 refs. FRANCE
Society meeting in Stuttgart, 21-22 May 1987. A general description of solid silicone rubber is followed by suggestions for the design of suitable extruders, infrared and hot air ovens for crosslinking, and the press moulding of silicone rubbers. Liquid silicone rubbers are discussed as an alternative to the solid material and the use of twocomponent silicone rubbers is described. Injection moulding of the two forms is compared and the possibility of multi-component metering and mixing of the liquid rubber discussed. WURTTEMBURG ENGINEERING SOCIETY; WURZBURG SOUTH GERMAN PLASTICS FEDERATION WEST GERMANY
Accession no.348992 Item 442 Plaste und Kautschuk 34,No.5,May 1987,p.183-90 German PHOTOCROSSLINKING OF SILICONES Mueller U;Timpe H J;Roesler H MERSEBURG,TECHNISCHE HOCHSCHULE; VEB CHEMIEWERK NUENCHRITZ This is a detailed review on developments in photocrosslinking of silicones. Principles of photochemical curing are discussed, types of photocrosslinkable silicones described and aspects of application considered. Main application areas for photocrosslinked silicones are in the production of printing plates and photoresists. 107 refs. EAST GERMANY
Accession no.348715 Item 443 Pitture e Vernici 63,No.8,Aug.1987,p.13-33 RHODORSIL Molteni C (Italian and English). A detailed account is presented of the chemistry and technical properties of silicone polymers in building preservation and restoration. 21 refs. RHONE-POULENC ITALIA SPA ITALY
Accession no.348044
Accession no.352270 Item 441 Gummi Fasern Kunststoffe 40,No.9,Sept.1987,p.506-8 German MANUFACTURE WITH SOLID AND LIQUID SILICONE RUBBERS
Item 444 132nd Meeting,Fall 1987.Preprints. Cleveland,Ohio,Oct.6-9,1987,Paper 9 SILICONE RUBBER, ITS DEVELOPMENT AND TECHNOLOGICAL PROGRESS Polmanteer K E (ACS,Rubber Div.)
Proceedings are reported of the Wurzburg South German Plastics Federation and the Wurttemburg Engineering
The development and technological progress of silicone rubber since it first became commercially available within
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149
References and Abstracts
the USA in 1944 from both the Dow Corning Corp. and the General Electric Co. are discussed. The key advances in tensile strength, room temp. vulcanisation, copolymers, new silicas, water-based compounds, high tear/tough compounds, liquid rubber, the Silastic Compounding System, cost/performance and medical grade rubber, responsible for the technological progress of silicone rubber are chronologically traced from 1944 to 1987. Finally, the combined silicone rubber technology as it commercially exists in 1987 is discussed. 33 refs. DOW CORNING CORP.; GENERAL ELECTRIC CO. USA
Accession no.344588 Item 445 Elastomerics 119,No.8,Aug.1987,p.20-2 TECHNICAL INNOVATIONS ENHANCE COMMERCIAL VALUE OF SILICONE RUBBER Toub M R GENERAL ELECTRIC CO. The article looks at the value of silicone rubber in a diversified elastomer market. Silicone sales trends are examined with respect to physical properties and application areas such as the automotive, aerospace, wire, cable and medical markets. 4 refs. GENERAL ELECTRIC CO.,SILICONE PRODUCTS DIV. USA
Accession no.341536 Item 446 High Performance Polymers: Their Origin and Development.Proceedings of the Symposium held New York,15-18 April 1986. New York,NY,Elsevier Science Publishing Co.Inc.,1986,p.381-8. 63E HISTORY OF SILICONE ELASTOMERS Fearon F W G DOW CORNING CORP. Edited by: Seymour R B;Kirshenbaum G S (ACS) Key discoveries in the development of silicone elastomer technology were reviewed with comment on monomer (chlorosilanes, siloxanes) synthesis and polymerisation (thermal condensation, ring-opening, emulsion), reinforcement (fumed silica fillers, copolymerisation, block copolymers, blends, IPN’s), crosslinking (peroxides, reactive group incorporation, RTV systems, one- and two-component systems), processing and fabrication, and properties. Composition and structural features responsible for the characteristic properties were discussed and related to applications. 27 refs. USA
Accession no.330649
150
Item 447 Cyclic Polymers. Barking,Elsevier Applied Science Publishers Ltd.,1986,p.85-133. 6116 PREPARATION OF CYCLIC POLYSILOXANES Wright P V;Beevers M S ASTON,UNIVERSITY; SHEFFIELD,UNIVERSITY Edited by: Semlyen J A (York,University) Essential procedures used in preparing and analysing the products of cyclisation reactions and in separating fractions of cyclic siloxane material were described in this review. The formation of siloxane rings in equilibrates and in irreversible processes, the critical concentration in polysiloxane equilibrates (theory,influence of substituents on cyclic formation, thermodynamic influences on equilibrium position, distribution and configurational isomers of cyclic phenylmethylsiloxanes), preparation of siloxane cyclic residues (reaction quenching, fractionation), analytical GPC (cyclic and linear distributions within macrocyclic residues), preparative GPC, and ring-chain equilibration of siloxane copolymers (polytetramethyloxadisilacycloheptane, copolymers of polysiloxane and PS segments) were discussed with relevant equations. 75 refs. UK
Accession no.329122 Item 448 Applied Polymer Science 2nd Edn.,ACS Symposium Series 285. Washington D.C.,1985,p.1117-40. 012 RESINS AND ADDITIVES CONTAINING SILICON Thames S F SOUTHERN MISSISSIPPI,UNIVERSITY Edited by: Tess R W;Poehlein G W (ACS,Div.of Polymeric Materials Science & Engng.) Silicon and carbon compounds were compared by considering inductive effects and (p-d) pi bonding, bond strengths (silicon bonds to halogen, carbon including double bond, hydrogen, oxygen and nitrogen). The characteristics of silicone polymers (enhanced thermal stability, higher water repellency, incompatibility with organic materials) and their resultant applications, siliconcontaining polymers (high-temperature coatings, blends), pigmentation, silicones as water repellents, and silicones as additives (paint formulation, coupling agents, incorporation into main chain to lower Tg of polyamides and polyimides). 29 refs. USA
Accession no.320195 Item 449 Kautchuk und Gummi Kunststoffe 39,No.1,Jan.1986,p.33-6
© Copyright 2001 Rapra Technology Limited
References and Abstracts
German SILICON RUBBERS - A SURVEY Bittera J WACKER CHEMIE GMBH A report on silicon rubbers is given which divides the materials into different crosslinking categories. These are: one- and two-component RTV types; addition crosslinkable HTV types (liquid, dispersion and solid rubbers); peroxide crosslinkable rubbers; and irradiation crosslinkable HTV types. Properties and application areas for these rubbers are indicated. (DKG Conference, Hanover,March 1985). WEST GERMANY
Accession no.317150 Item 450 Adhesives Age 29,No.6,31st May 1986,p.8-11 SILICONE SEALANT TECHNOLOGY, MARKETS CONTINUE TO GROW Elias M SEALANTS TREMCO INC. An overview of one-component silicone sealant technology and applications is presented, with information being provided on the chemistry of these sealants, defining the desired property profile, compounding and end-use applications. Basic high, medium and low modulus formulations containing acetoxy, oxime and amine crosslinkers are tabulated along with suitable fillers. 5 refs. USA
Accession no.315239
examination of their cost-effectiveness, particularly as functional, rather than fashionable, constituents of hair care preparations. UK
Accession no.301333 Item 453 Plastics for Electronics. Barking,Elsevier Applied Science Publishers Ltd.,1985,pp.67-97. 6E SILICONE PROTECTIVE ENCAPSULANTS AND COATINGS FOR ELECTRONIC COMPONENTS AND CIRCUITS Davis J H DOW CORNING LTD. Edited by: Goosey M T (Dynachem Corp.) Silicones were defined and their physical properties (thermal and oxidative stabilities, stability in physical and dielectric characteristics with temperature, surface, handling, fire resistance, combustion products, chemical purity, low water absorption), production and typical products were indicated before reviewing the different types of silicone and their application in electronics. Oneand two-component elastomeric sealants and encapsulants, conformal coatings and impregnating resins, transfer moulding compounds, performance, high purity coatings and adhesives, insulating and constructional materials, wire and cables, silicone aids in electronic production, and future developments were discussed. 20 refs. UK; USA
Accession no.300427
Item 451 Advances in Polymer Science No.68/69,1985,p.216-25 POLYSILOXANES Penczek S;Kubisa P;Matyjaszewski K The literature on the synthesis of polysiloxanes by cationic ring-opening polymerisation is reviewed. Aspects covered include the synthesis of polydimethylsiloxanes from octamethylcyclotetrasiloxane, telomerisation, polymerisation of alkylhydrosiloxanes, macrocyclisation, and the polymerisation mechanism. 35 refs. POLAND
Accession no.304786 Item 452 Manufacturing Chemist 56,No.11,Nov.1985,p.59 COMPARING SILICONE COSTEFFECTIVENESS Alexander P A review is given of silicone-based cosmetic raw materials, including polyether polysiloxanes, with an
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151
References and Abstracts
152
© Copyright 2001 Rapra Technology Limited
Subject Index
Subject Index A ABRASION RESISTANCE, 14 34 42 119 145 161 218 233 306 313 334 347 382 ABS, 14 237 238 ACCELERATED TEST, 269 338 394 395 ACCELERATOR, 304 329 331 ACID RESISTANCE, 74 249 293 ACOUSTIC INSULATION, 367 381 ACRYLIC ELASTOMER, 287 291 383 ACRYLIC RESIN, 14 247 286 379 390 422 ACTIVATION ENERGY, 200 246 312 ACTIVATOR, 304 ADDITION CURING, 163 165 ADDITION POLYMERISATION, 64 129 143 213 423 ADDITION REACTION, 17 34 41 65 89 250 261 263 ADDITIVE, 14 25 26 37 38 58 81 92 98 103 105 129 131 138 159 167 181 185 187 188 194 200 202 218 219 222 237 238 246 248 249 250 292 293 295 304 311 312 325 331 342 346 363 372 379 392 421 440 448 ADHESION, 25 26 59 60 64 65 77 89 90 97 105 115 125 136 138 150 168 186 206 229 236 238 250 261 295 313 338 370 377 380 381 390 392 394 395 415 423 429 440 448 ADHESION PROMOTER, 38 81 201 415 ADHESIVE, 40 52 75 121 126 140 147 238 244 338 368 372 377 380 387 396 417 430 434 435 439 440 453 ADHESIVE TAPE, 96 380 429 ADSORPTION, 32 70 300 AEROSPACE APPLICATION, 7 15 72 168 185 219 255 258 319 336 343 363 377 430 431 445 AESTHETIC, 14 237 AGEING, 20 129 131 138 202 205 217 219 248 249 250 269 280 287 291 313 343 363 394 AIR BAG, 25 42 63 77 121 123 126 144 159 161 255 313 404 AIR CONDITIONING, 319
AIR CURING, 379 AIR ENTRAPMENT, 414 AIR EVACUATION, 227 AIR INTAKE SYSTEM, 64 AIR POLLUTION, 137 ALKOXYSILANE, 10 211 250 ALLERGY, 30 100 ALUMINIUM FOIL, 303 353 ALUMINIUM HYDROXIDE, 17 41 109 371 ALUMINIUM OXIDE, 10 162 AMINOPROPYLTRIETHOXYSILANE, 274 AMINOSILANE, 408 AMMUNITION, 295 ANALYSIS, 28 69 92 94 200 208 217 225 246 253 292 294 307 310 318 325 326 342 347 447 ANCILLARY EQUIPMENT, 2 359 ANIMAL TESTING, 217 ANTI-ADHESIVE PROPERTIES, 26 138 ANTI-FOAMING AGENT, 140 304 368 ANTIFOULING, 43 ANTI-SCORCH AGENT, 53 ANTI-SLIP PROPERTIES, 25 ANTIOXIDANT, 293 304 ANTISTATIC PROPERTIES, 218 ARAMID FIBRE, 303 ARC RESISTANCE, 137 219 ARCHITECTURAL APPLICATION, 138 ARMCHAIR, 14 ART, 138 403 ARTIFICIAL BONE, 4 373 409 ARTIFICIAL BREAST, 26 69 111 122 152 195 199 208 216 217 242 259 279 283 296 318 350 389 ARTIFICIAL HIP, 344 ARTIFICIAL JOINT, 373 ARTIFICIAL LIMB, 360 ARTIFICIAL MUSCLE, 178 ARTIFICIAL OESOPHAGUS, 361 ARTIFICIAL ROCK, 62 ARTIFICIAL SKIN, 325 ARTIFICIAL TEETH, 14 ARTIFICIAL TENDON, 174 ASSEMBLY, 91 121 AUTOCLAVE, 131 341 AUTOIMMUNE DISEASE, 298 299 AUTOMATION, 2 104 121 126 150 193 234 235 243 248 256
© Copyright 2001 Rapra Technology Limited
326 374 385 393 AUTOMOTIVE APPLICATION, 6 7 11 13 15 25 26 27 35 40 42 48 54 60 63 64 72 77 79 82 89 103 105 114 118 121 123 124 126 144 150 159 161 163 166 168 175 179 181 185 191 193 194 196 202 204 215 219 226 235 238 243 250 255 257 258 263 269 273 275 284 287 290 291 294 303 311 313 321 325 327 339 349 353 355 363 364 367 368 375 377 378 380 381 385 391 392 404 405 408 412 413 427 431 445 AXLE, 38
B BABY FEED BOTTLE, 37 224 304 364 BACTERIA, 236 268 366 BAG, 352 BALLOON, 30 176 BALLOON CATHETER, 29 BARIUM, 384 BARREL, 179 BARREL TEMPERATURE, 200 227 229 246 BARRIER, 168 331 352 394 BATH, 238 BELLOWS, 250 BELT, 306 313 BENCH, 347 BENDING STRENGTH, 4 BENZOYL PEROXIDE, 33 112 BETA RAY, 239 BETA-ESTRADIOL, 340 BIDET, 422 BINDER, 187 403 426 BIOCHEMISTRY, 217 253 298 BIOCOMPATIBILITY, 14 23 24 25 30 31 39 57 61 68 71 87 91 100 128 131 133 134 135 172 173 174 186 197 199 203 206 236 239 255 265 266 268 278 279 280 281 283 296 315 384 389 399 407 409 416 BIODEGRADATION, 134 216 217 283 296 298 340 366 BIOLOGICAL ATTACK, 370 389 BIOMATERIAL, 23 24 31 61 71 80 87 128 133 135 172 174 186 198 199 206 239 247 278 280 281 283 286 296 297 298 300
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Subject Index
308 314 315 361 370 399 BIOMEDICAL APPLICATION, 21 30 31 39 131 188 197 217 283 389 399 BLEED-THROUGH, 203 BLEEDING, 218 219 BLEND, 17 41 68 118 200 237 238 276 328 446 448 BLOCKING RESISTANCE, 103 BLOOD CONTACT APPLICATION, 131 158 296 BLOWING AGENT, 88 136 BOND STRENGTH, 11 59 60 125 415 448 BONDING, 9 59 64 89 125 202 211 218 295 338 392 421 BONDING AGENT, 52 147 295 BOROSILICATE, 295 BOTTLE, 37 224 BREAK RESISTANCE, 189 BREAKING STRENGTH, 7 BREATHABILITY, 168 BRIDGE, 72 BUILDING APPLICATION, 26 40 72 76 138 140 187 215 226 238 324 352 362 363 365 394 395 404 422 423 431 438 443 BUMPER, 159 BURST STRENGTH, 428 BUSHING, 41 229 367 BUSINESS MACHINE, 194 219 234 255
C C-FRAME, 150 CABLE, 6 11 20 26 33 106 112 159 185 219 249 250 303 311 313 332 343 352 353 363 371 392 445 453 CABLE CONNECTOR, 15 185 CABLE SUPPORT, 319 CALCIUM CARBONATE, 1 256 408 CALORIMETRY, 221 CAP, 204 222 CAPACITY, 226 CAPILLARY RHEOMETRY, 246 292 310 CAPSULE, 239 323 432 CAR, 25 26 105 150 159 185 193 194 202 219 238 250 263 269 294 303 311 313 325 353 363 380 385 392 405 CARBON BLACK, 46 105 127 218 250 CARBON DIOXIDE, 303 419 CARBON FIBRE, 19 165 295 336
154
400 CARBORANE SILOXANE POLYMER, 371 CARCINOGEN, 111 208 242 304 350 389 399 CASING, 194 CAST, 45 107 141 182 393 CASTING, 14 26 175 194 237 295 331 357 393 CATALYST, 5 17 38 81 88 95 97 157 201 202 232 251 256 400 408 434 CATALYTIC CONVERTER, 219 CATHETER, 24 29 100 147 156 163 176 206 268 311 370 384 CAVITY PRESSURE, 104 CELL CULTURE, 23 186 296 CELLULAR MATERIAL, 14 88 94 99 136 192 238 285 306 352 381 387 389 392 394 436 CERAMIC, 13 155 164 187 312 338 352 388 422 426 CERAMIC FIBRE, 426 CEREBROSPINAL FLUID SHUNT, 221 CERTIFICATION, 234 243 262 263 353 CHAIN SCISSION, 131 200 363 CHAIR, 14 CHALK, 408 CHARACTERISATION, 51 145 225 239 316 CHEMICAL MODIFICATION, 3 21 56 65 75 92 103 131 202 217 301 406 CHEMICAL PROPERTIES, 7 11 14 20 26 48 65 67 69 74 77 81 91 103 118 119 131 148 159 168 169 185 202 218 240 417 425 426 439 CHEMICAL RECYCLING, 263 303 311 CHEMICAL RESISTANCE, 7 11 14 20 26 35 48 60 65 67 74 77 81 91 103 118 119 131 148 159 168 169 185 191 202 218 219 240 249 293 295 313 336 363 367 377 380 381 385 394 395 407 431 CHEMICAL STRUCTURE, 5 8 21 26 36 65 72 91 112 131 135 138 177 185 187 200 212 219 255 394 426 450 CHIP, 75 CHLOROSILANE, 328 363 446 CHONDROITIN SULFATE, 283 CHROMATOGRAPHY, 101 200 225
CLAMP FORCE, 2 150 179 229 234 235 248 326 341 374 385 CLAY, 110 331 CLEAN ROOM, 229 262 408 CLOSED MOULD, 295 311 CLOTHING, 25 168 263 303 311 313 353 CO-ROTATING EXTRUDER, 246 309 COATED FABRIC, 14 25 42 63 161 168 255 263 303 313 353 436 COATED PAPER, 25 346 COATING, 3 6 25 40 42 43 44 59 72 73 77 103 115 137 139 161 187 233 237 238 250 263 274 289 293 295 303 313 319 331 346 350 353 364 367 370 377 378 379 380 382 389 390 394 404 423 434 448 453 COCHLEAR IMPLANT, 265 COEFFICIENT OF FRICTION, 103 218 COEXTRUSION, 35 100 COINJECTION MOULDING, 26 60 102 119 173 179 185 261 COLD CURING, 14 26 363 COLD RUNNER, 2 9 102 104 119 150 173 193 204 207 227 235 248 273 282 311 385 COLLAGEN, 80 217 283 293 361 COLORABILITY, 219 COLORANT, 229 237 COLOUR, 2 14 131 157 218 219 229 237 248 295 302 311 331 408 422 COMBUSTION, 185 263 352 453 COMMERCIAL INFORMATION, 40 60 91 120 126 136 179 223 306 369 414 426 COMPATIBILITY, 15 21 102 103 290 377 COMPETITIVENESS, 381 COMPLEMENT ACTIVATION, 268 COMPOSITE, 14 19 33 50 55 80 89 127 142 149 150 153 183 196 210 238 240 245 246 251 263 275 295 303 317 319 323 335 336 337 353 360 374 382 385 391 400 410 417 426 428 COMPOUND, 26 202 249 269 292 342 417 COMPOUNDING, 14 26 40 77 137 185 189 200 202 248 250 309 311 342 363 392 424 450 COMPRESSION MOULDING, 14 56 77 91 163 185 200 234 269
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Subject Index
342 369 COMPRESSION PROPERTIES, 14 294 383 COMPRESSION SET, 65 77 95 97 154 166 179 202 218 219 248 249 250 269 291 342 383 441 COMPRESSION STRESS RELAXATION, 219 269 367 383 COMPUTER AIDED DESIGN, 28 64 83 141 180 237 238 294 310 405 COMPUTER AIDED MANUFACTURE, 405 COMPUTER APPLICATION, 52 243 COMPUTER CONTROL, 104 193 360 385 393 COMPUTER SIMULATION, 47 64 105 310 CONCRETE, 352 422 CONDENSATION POLYMERISATION, 85 143 191 328 423 435 446 CONDUCTIVE COATING, 289 CONDUCTIVE RUBBER, 218 250 263 275 289 303 311 312 336 353 CONFERENCE, 104 105 138 200 202 217 218 219 235 246 269 283 294 295 307 309 310 325 326 331 342 383 408 441 CONNECTOR, 27 60 106 114 235 400 CONSERVATION APPLICATION, 403 CONSTRUCTION, 352 CONSUMPTION, 40 77 179 185 226 255 368 376 CONTACT ANGLE, 20 21 65 97 167 205 206 236 239 CONTACT LENS, 21 264 419 CONTAMINATION, 20 109 137 262 407 CONTRACEPTIVE, 323 397 411 432 CONTROL, 2 104 119 132 179 193 234 235 273 385 393 CONTROLLED RELEASE, 156 188 221 267 301 340 372 432 CONVEYOR BELT, 313 COOLANT, 11 166 COOLER HOSE, 166 219 392 COOLING, 104 105 179 193 235 273 311 319 413 COOLING TIME, 105 CORE-PULLING, 326 CORK SUBSTITUTE, 219
CORNEA, 21 CORROSION RESISTANCE, 43 74 159 240 295 438 COSMETICS, 110 213 293 318 COST, 6 18 99 102 119 150 161 179 180 192 196 218 224 226 227 234 235 237 248 260 282 342 352 377 381 385 393 444 445 COUNTER-ROTATING EXTRUDER, 309 CRACK, 379 386 428 CRACKING, 202 292 295 347 386 428 CRANKSHAFT, 219 CRASH SIMULATOR, 325 CREASE RESISTANCE, 303 CROSSLINK, 1 201 250 263 293 303 304 311 353 359 379 395 433 439 446 449 CROSSLINK DENSITY, 51 101 188 200 213 218 269 283 342 356 CROSSLINKING, 18 21 39 46 51 54 65 68 78 81 89 131 157 163 165 173 197 200 202 209 218 227 229 328 395 439 446 449 CUP, 229 CURE RATE, 18 26 47 51 64 65 105 200 202 241 248 250 256 342 408 CURE TIME, 2 6 26 60 129 131 138 150 185 200 202 248 250 263 303 311 325 353 CURING, 1 3 6 8 10 12 14 15 25 26 34 40 41 47 48 49 59 65 68 75 78 90 91 103 107 112 119 120 124 131 132 135 138 152 153 154 159 163 165 185 194 200 202 235 238 244 263 270 271 288 290 292 295 307 310 320 325 331 339 342 346 348 363 377 379 380 383 385 393 395 408 411 414 431 434 435 438 441 450 CURING AGENT, 1 25 26 38 39 58 77 81 88 94 110 113 131 138 159 162 185 188 200 202 218 233 249 250 285 292 295 304 331 342 363 392 396 438 446 449 450 CURING SYSTEM, 120 219 CURING TEMPERATURE, 17 26 47 60 64 105 120 131 138 185 200 248 250 263 303 304 311 325 342 353 CUSHION, 228 CUSTOM MOULDING, 344
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CYCLE TIME, 60 64 65 105 150 173 179 185 193 224 229 234 235 248 250 331 342 CYTOTOXICITY, 23 25 61 131 143
D DAMP-PROOFING, 187 DECORATION, 238 349 355 DEFECT, 18 248 292 331 366 DEFENCE APPLICATION, 295 336 DEFORMATION, 105 246 247 283 292 294 310 344 DEGRADATION, 4 20 129 131 138 202 205 216 217 219 240 258 283 338 347 366 367 380 389 394 407 DEMAND, 7 35 40 118 181 376 DEMOULDING, 2 49 104 185 193 204 227 248 269 305 326 331 385 DENSITY, 65 94 167 192 249 292 336 338 352 408 DENTAL APPLICATION, 14 26 53 143 240 247 281 286 382 398 DEODORANT, 110 DESIGN, 9 18 28 29 49 67 105 119 141 158 161 180 189 204 207 220 234 237 238 243 264 294 331 338 375 405 DEVOLATILISATION, 185 246 309 DIAGNOSTIC APPLICATION, 22 DIALYSIS, 263 303 DIAPHRAGM, 250 DIATOMACEOUS EARTH, 441 DIE, 73 75 160 238 260 292 309 310 359 DIE SWELL, 220 310 DIELECTRIC CONSTANT, 3 5 380 DIELECTRIC LOSS, 312 371 DIELECTRIC PROPERTIES, 131 185 249 293 311 312 363 371 380 453 DIFFERENTIAL THERMAL ANALYSIS, 92 239 245 402 420 DIFFUSION, 15 21 82 98 142 188 195 267 301 308 340 389 DIMENSIONAL STABILITY, 130 138 248 263 272 281 303 305 311 331 348 353 398 DIPPING, 304 357 DIRECT EXTRUSION, 327
155
Subject Index
DIRECT INJECTION, 173 193 DIRECTIVE, 262 DISC DRIVE, 306 DISPERSION, 74 76 276 284 293 357 449 DISPLAY DEVICE, 289 DIVING MASK, 227 DO-IT-YOURSELF, 226 DOMESTIC EQUIPMENT, 26 54 79 194 226 238 368 391 DOOR, 88 238 362 422 DOOR SEAL, 219 DOPANT, 312 379 DOSING, 104 227 DRUG DELIVERY, 98 100 184 188 267 271 301 DUAL HARDNESS, 119 179 DUCT, 352 DUMMY, 118 192 250 263 303 304 DURABILITY, 68 243 269 367 381 395 412 417 437 439 DYNAMIC MECHANICAL PROPERTIES, 310 428
E EARPLUG, 263 303 ECONOMIC INFORMATION, 7 35 40 60 77 89 99 103 118 148 161 179 181 185 226 235 255 257 376 377 445 ELASTICITY, 4 5 18 21 25 84 90 131 138 159 167 185 237 271 292 294 311 379 395 433 ELECTRICAL APPLICATION, 20 26 33 41 55 59 72 73 77 84 96 106 112 114 159 194 209 215 219 222 238 249 250 255 257 289 290 311 313 333 334 343 353 354 363 405 431 445 453 ELECTRICAL CONDUCTIVITY, 67 127 165 218 229 250 263 275 289 303 311 312 353 ELECTRICAL CONNECTOR, 27 60 211 219 311 ELECTRICAL INSULATION, 3 5 17 20 26 41 67 73 102 109 112 118 137 159 163 173 181 189 219 249 255 293 313 332 343 363 380 381 388 390 ELECTRICAL PROPERTIES, 3 5 17 20 26 41 56 65 73 78 91 109 112 118 127 131 148 159 163 173 179 181 185 218 219 222 235 248 249 250 263 274 275 290 293 303 311 312 348 353
156
363 371 377 380 425 431 436 437 ELECTROLUMINESCENCE, 36 209 212 354 ELECTROMAGNETIC SHIELD, 336 ELECTRON BEAM, 346 ELECTRON BEAM CURING, 8 363 372 434 ELECTRONIC APPLICATION, 1 3 5 7 8 36 52 54 59 72 74 79 84 86 116 194 232 238 244 250 257 263 270 274 277 290 303 311 329 336 339 348 353 364 369 377 378 380 390 391 400 453 ELONGATION, 63 65 68 90 129 131 157 167 200 202 218 219 228 235 248 249 291 295 342 345 408 441 ENCAPSULATION, 74 184 270 274 293 329 391 400 417 453 ENDOSCOPE, 100 ENERGY CONSUMPTION, 13 81 173 200 248 342 ENGINE, 13 159 219 223 319 321 327 335 ENGINE MOUNTING, 11 ENGINE OIL, 291 ENGINEERING APPLICATION, 14 65 238 439 ENVIRONMENT, 103 263 282 303 353 377 ENVIRONMENTAL RESISTANCE, 137 389 417 EPOXY RESIN, 12 19 138 305 328 329 331 351 390 415 ESTRADIOL, 340 ETCHING, 164 295 312 ETHYLENE OXIDE, 131 239 ETHYLENE-PROPYLENEDIENE TERPOLYMER, 18 20 109 219 367 408 EXHAUST SYSTEM, 11 60 EXPOSURE LIMIT, 208 304 EXPOSURE TIME, 131 202 208 217 219 EXTRACTION, 69 200 271 304 EXTRUDATE, 292 310 401 EXTRUDER, 73 160 246 309 310 359 411 EXTRUSION, 7 14 26 49 54 85 91 101 108 151 159 160 171 185 200 201 230 238 246 249 276 285 292 309 310 321 327 359 363 401 413 431 441 EXTRUSION MOULDING, 162
EYE DAMAGE, 21 80
F FABRIC, 14 25 42 63 161 168 313 364 378 FABRIC REINFORCED, 319 FABRICATION, 75 91 141 271 354 425 FACE MASK, 325 FAILURE, 66 105 111 122 189 295 327 366 FAST CURING, 26 FATIGUE, 28 219 252 FEEDING, 104 160 201 248 295 374 FIBROBLAST, 186 198 239 283 FILLER, 14 25 26 37 38 41 46 58 64 65 76 81 85 92 105 109 113 127 131 137 138 162 165 167 183 185 189 191 201 202 218 219 222 238 246 250 255 256 276 292 295 304 325 329 331 363 371 384 391 392 394 439 444 446 450 FILM, 3 8 32 39 42 44 168 206 236 238 300 312 319 377 394 399 440 FINISHING, 181 237 385 FINITE ELEMENT ANALYSIS, 28 246 294 310 326 FIREPLACE, 422 FLAME RETARDANT, 33 219 222 232 238 276 311 352 371 381 394 453 FLAMMABILITY, 25 26 185 192 215 219 222 238 248 249 263 276 303 311 313 319 342 353 362 363 371 394 407 436 453 FLASH, 104 227 400 FLASH REMOVAL, 269 385 441 FLASHLESS, 2 185 202 234 248 311 326 FLEXIBILITY, 15 25 64 65 105 118 194 219 227 229 237 248 249 313 319 343 348 352 364 373 409 423 FLEXURAL PROPERTIES, 56 105 190 237 FLOW, 18 58 132 200 220 236 246 292 307 309 310 331 342 FLOW RATE, 179 200 246 271 307 309 FLUE, 77 FLUID, 38 45 202 211 246 271 293 FLUID RESISTANCE, 202 FLUOROELASTOMER, 34 77
© Copyright 2001 Rapra Technology Limited
Subject Index
127 219 249 258 FLUOROSILICONE RUBBER, 77 127 148 185 238 248 294 336 377 430 437 FOAM, 14 88 94 136 192 238 251 285 318 319 350 352 381 387 389 392 394 436 FOAM-IN-PLACE, 99 136 FOGGING, 303 FOOD-CONTACT APPLICATION, 25 26 54 185 215 218 229 255 262 304 313 407 408 FOOTWEAR, 228 345 408 FORM-IN-PLACE, 339 FORMULATION, 46 90 103 166 189 222 241 264 287 340 381 395 430 431 444 448 450 FRACTURE MORPHOLOGY, 20 133 186 208 231 FREE RADICAL, 75 131 250 FRICTION PROPERTIES, 35 103 145 218 FUEL HOSE, 77 FUEL RESISTANCE, 77 148 159 FUMED SILICA, 92 219 251 446 FURNITURE, 14 103
G GAMMA-IRRADIATION, 131 GAS INJECTION MOULDING, 18 102 132 238 285 GAS PERMEABILITY, 21 138 264 313 418 GASKET, 13 35 38 48 81 95 118 136 150 181 196 202 219 223 256 269 285 291 294 306 324 336 339 367 368 383 392 412 GATE, 104 119 227 229 307 311 331 GEL, 21 26 27 66 84 101 110 111 114 122 151 159 178 188 195 199 203 213 217 218 238 270 274 296 318 322 358 380 387 389 GLASS, 12 14 138 334 394 422 GLASS FIBRE, 14 62 150 238 364 374 379 385 400 417 GLASS TRANSITION TEMPERATURE, 131 245 316 329 363 379 380 400 443 448 GLAUCOMA, 57 GLAZING, 138 226 324 368 394 408 GLOSS, 14 103 GRANULE, 26 304 GREASE RESISTANCE, 249
GREEN STRENGTH, 160 295 GRINDING, 200 218 GROMMET, 219 294 380 GROWTH RATE, 7 40 48 77 102 103 118 185 226 336 368 GUN, 305
H HAIR CONDITIONER, 452 HARDNESS, 14 26 65 90 95 105 107 114 129 131 138 157 160 179 182 185 194 202 207 218 219 227 229 235 248 249 263 291 292 294 303 311 331 353 364 383 393 408 HEAD REST, 14 HEALTH HAZARD, 14 25 66 111 131 143 185 192 203 208 210 259 271 318 322 323 350 389 390 407 HEART VALVE, 28 128 HEAT AGEING, 65 177 202 219 249 269 383 392 HEAT CURING, 14 15 25 26 40 48 78 120 131 138 159 163 185 235 238 244 255 292 310 313 363 368 379 383 392 HEAT INSULATION, 55 118 HEAT RESISTANCE, 7 11 14 15 25 26 46 48 50 60 64 77 90 105 118 121 126 129 131 138 148 159 169 179 185 194 202 218 219 227 229 235 248 250 263 269 290 291 293 295 303 311 313 329 343 353 363 380 385 391 392 412 422 437 445 HEAT SHIELD, 303 313 HEATER HOSE, 392 HERMETIC SEAL, 121 126 270 293 HIGH-PERFORMANCE, 82 303 377 378 HIGH TEMPERATURE, 196 249 269 412 413 448 449 HIGH VOLTAGE APPLICATION, 41 189 219 222 HINGE, 331 373 HIP JOINT, 344 HISTOLOGY, 172 266 361 HISTORY, 90 139 140 148 363 376 446 HOLDING PRESSURE, 64 105 HOLDING TIME, 227 229 HOLLOW ARTICLE, 18 HOSE, 18 77 123 149 159 166 171 219 319 335 368 392 413 HOT CURING, 14 15 25 26 40 48
© Copyright 2001 Rapra Technology Limited
78 120 131 138 159 163 185 235 238 441 HOT MELT ADHESIVE, 377 HOUSEWARES, 54 79 HYDRAULIC, 150 248 311 326 385 HYDROGEL, 21 264 370 HYDROLYSIS, 5 138 177 191 205 216 217 328 363 389 439 HYDROLYTIC STABILITY, 21 185 205 HYDROPHILIC, 21 184 188 264 419 423 HYDROPHOBIC, 20 21 89 137 138 188 189 218 236 293 389 423 HYDROSILYLATION, 3 56 65 75 202 363 396 HYDROTHERMAL STABILITY, 338 415 HYPODERMIC SYRINGE, 115
I IMMERSION, 202 269 379 383 IMMUNOLOGY, 22 298 299 300 IMPACT PROPERTIES, 14 25 56 189 276 325 IMPLANT, 4 28 31 57 66 69 80 87 111 122 131 172 195 198 199 203 210 216 217 229 239 266 279 280 283 296 297 298 299 300 314 315 322 323 338 340 350 358 361 366 373 384 389 397 399 409 432 IMPRESSION MOULD, 53 IN-VITRO, 57 217 268 278 296 298 389 IN-VIVO, 69 87 143 217 296 298 389 INDOMETHACIN, 267 INDUSTRIAL APPLICATION, 72 140 148 352 377 INDUSTRIAL ROBOT, 2 150 193 326 INERT, 7 68 300 INFLAMMATION, 268 297 INFLATABLE, 25 176 358 INFLATION PRESSURE, 294 INHIBITOR, 157 331 INJECTION COMPRESSION MOULDING, 14 INJECTION MOULD, 2 104 105 150 185 193 248 250 263 265 295 303 304 307 311 325 326 342 353 363 385 391 405 INJECTION MOULDING, 2 7 9 11 14 15 18 26 47 49 60 64 65
157
Subject Index
77 79 83 89 91 95 97 102 104 105 118 125 129 132 150 154 157 159 163 165 169 173 179 180 181 185 190 193 202 204 207 219 223 224 229 234 235 238 243 251 257 260 261 282 290 329 344 348 349 355 364 378 385 414 441 INJECTION MOULDING MACHINE, 2 9 67 79 102 119 193 223 227 260 273 341 374 INJECTION PRESSURE, 65 173 202 229 248 250 305 326 INJECTION TRANSFER MOULD, 295 INJECTION UNIT, 2 119 150 193 235 273 INSERT, 2 150 194 295 331 INSERT MOULD, 11 60 64 65 89 105 150 238 248 250 295 INSERT MOULDING, 2 26 150 185 229 369 INSOLE, 228 345 INSULATION, 20 26 41 55 96 118 224 334 453 INTEGRATED CIRCUIT, 8 232 270 329 380 INTERFACIAL ADHESION, 105 429 INTERNAL COMBUSTION ENGINE, 13 INTRAOCULAR LENS, 16 IRON OXIDE, 38 81 129 157 219 IRRITANT, 131
K KEY, 116 KEYBOARD, 116 238 243 250 263 303 311 353 KEYBOARD MAT, 234 243 KEYPAD, 1 52 163 179 219 224 303 369
L LACQUER, 390 LAMINATE, 65 349 355 381 400 417 LAPAROSCOPE, 100 LARGE-COMPONENT, 67 193 LATEX, 7 100 102 293 304 LAWSUIT, 210 322 323 LEAD TIME, 60 83 341 LEAKAGE, 137 195 269 274 298 LEGISLATION, 103 111 131 242 262 304 LENS, 16 21 238 419
158
LEVONORGESTREL, 323 397 432 LIFETIME PREDICTION, 271 LIGHT DEGRADATION, 26 312 363 394 437 LIGHT-EMITTING DIODE, 36 212 354 LIGHT RESISTANCE, 26 185 248 250 311 380 LIGHT TRANSMISSION, 107 116 182 LIGHTING APPLICATION, 238 LIGHTNING CONDUCTOR, 67 LIMITING OXYGEN INDEX, 249 LINING, 149 228 LIPID, 21 195 217 LIQUID CASTING, 295 LIQUID INJECTION MOULDING, 7 15 65 89 91 95 97 102 104 159 179 180 185 193 202 219 223 235 238 243 248 250 263 282 295 303 304 311 326 341 342 353 363 368 369 385 405 LIQUID POLYMER, 95 97 132 154 207 214 284 339 355 400 LIQUID RUBBER, 11 15 18 26 40 47 49 51 54 60 64 65 67 77 79 89 102 104 105 118 119 132 138 157 159 161 163 173 179 182 185 193 202 204 219 224 227 229 234 238 241 243 248 250 255 257 260 263 273 282 295 303 304 311 313 326 342 348 349 353 363 369 374 378 385 387 405 414 441 444 449 LITHOGRAPHY, 71 141 312 LONG-TERM, 20 21 34 45 274 LOW TEMPERATURE CURING, 377 LOW TEMPERATURE PROPERTIES, 15 77 118 179 219 227 235 248 249 287 291 313 380 422 LOW TEMPERATURE RESISTANCE, 219 LOW VISCOSITY, 104 138 204 227 248 250 257 348 LUBRICANT, 24 38 82 115 159 202 293 363 392 423 LUMINESCENCE, 36 209
M MACHINERY, 2 9 14 25 51 62 67 73 79 102 104 105 119 150 160 179 182 185 193 194 223 227 229 234 235 237 246 248 250
260 305 307 309 310 311 320 325 326 327 331 342 355 359 385 393 405 MACHINING, 237 MACROPHAGE, 217 239 278 389 MAGNESIUM OXIDE, 38 81 219 MAGNETIC PROPERTIES, 217 293 MAGNETIC RESONANCE IMAGING, 174 MANDREL, 34 310 MANIFOLD, 326 367 MANNEQUIN, 192 325 MARINE APPLICATION, 72 MARKET, 99 161 185 259 329 368 377 413 445 MARKET GROWTH, 181 MARKET SHARE, 40 77 89 103 179 226 235 255 336 368 MASK, 325 MASTERBATCH, 26 131 MATERIAL REPLACEMENT, 7 30 42 94 100 102 116 134 156 224 234 242 243 282 330 404 409 410 MATERIALS SELECTION, 91 146 149 168 352 MAXILLO-FACIAL SURGERY, 167 MECHANICAL PART, 150 159 185 202 219 250 255 263 269 293 294 295 303 311 353 363 380 383 385 392 MECHANICAL PROPERTIES, 4 7 14 15 17 18 21 24 25 26 28 34 35 42 50 53 56 63 64 65 69 77 78 84 89 90 91 92 93 94 95 97 101 103 105 106 108 114 118 119 124 125 129 130 131 134 138 145 154 157 159 160 161 166 167 174 179 184 185 189 190 194 200 202 205 207 214 218 219 221 227 228 229 233 235 237 241 243 246 247 248 249 250 252 257 263 265 269 276 283 286 287 291 292 294 295 303 304 306 307 310 311 312 313 319 325 329 331 334 342 343 345 347 348 352 353 363 364 367 373 375 379 380 381 382 383 389 392 393 394 395 398 425 433 436 MEDICAL APPLICATION, 4 7 21 22 23 24 25 26 28 29 30 31 39 40 54 57 60 61 64 66 68 69 71 79 91 100 106 115 128 131 133 142 146 147 152 156 163 168 170 172 174 176 178 180 183
© Copyright 2001 Rapra Technology Limited
Subject Index
185 186 188 197 203 205 206 208 210 215 217 225 228 229 250 254 255 257 263 264 265 266 271 280 283 293 296 302 303 308 311 314 315 323 330 337 340 341 343 345 353 357 360 361 363 364 370 373 378 384 387 389 397 407 411 416 431 435 444 445 MEDICAL EQUIPMENT, 83 100 158 176 262 353 MELT TEMPERATURE, 104 307 309 MELT VISCOSITY, 292 307 316 329 MEMBRANE, 11 15 71 118 159 185 188 243 263 294 311 402 418 419 METAL ADHESION, 60 65 77 338 METAL COATING, 336 METAL FILLER, 41 218 336 METAL INSERT, 150 194 250 295 331 METAL REPLACEMENT, 14 391 METERING, 9 89 229 243 321 MICROMOULDING, 9 164 MICROWAVE HEATING, 254 MIGRATION, 15 20 21 66 82 103 137 195 217 298 300 304 389 407 MILITARY APPLICATION, 96 295 319 430 MILLING, 65 163 255 357 MINERAL FILLER, 26 55 185 202 238 329 363 391 MIXER, 157 311 MIXING, 1 14 26 46 89 171 181 185 194 200 202 227 229 235 246 248 250 287 291 309 311 392 393 413 414 441 MOBILE PHONE, 60 MODULUS, 131 200 219 249 269 291 295 450 MOISTURE CURING, 6 138 363 408 MOISTURE RESISTANCE, 137 159 185 274 377 MOLECULAR STRUCTURE, 5 8 21 26 36 65 72 91 112 131 135 138 163 177 185 187 195 200 212 219 239 245 249 250 255 267 292 312 316 328 346 363 394 395 406 426 434 436 437 446 447 448 450 MOLECULAR WEIGHT, 21 26 65 68 69 138 152 185 195 200 213 280 289 293 356
MOONEY VISCOSITY, 292 MORPHOLOGY, 20 133 186 208 231 239 245 406 MOTOR CYCLE, 19 MOULD, 2 104 105 107 150 185 193 194 204 234 235 237 248 250 257 272 288 307 311 320 325 326 331 342 344 359 385 393 398 405 423 431 MOULD CAVITY, 117 190 331 MOULD CLOSING, 150 248 MOULD COOLING, 193 MOULD CYCLE, 150 185 193 248 250 331 MOULD DESIGN, 9 18 49 67 105 204 243 331 344 405 MOULD FILLING, 47 64 104 105 119 190 193 227 229 307 331 MOULD FLOW, 257 307 331 342 MOULD HEATING, 49 193 260 263 303 311 331 MOULD INSERT, 83 331 MOULD MAKING, 57 102 317 MOULD RELEASE, 58 60 89 MOULD RELEASE AGENT, 40 58 113 331 363 423 MOULD SLIDE CORE, 65 MOULD TEMPERATURE, 64 65 89 104 105 118 119 150 193 202 207 211 227 229 248 250 304 307 342 344 353 MOULDING, 9 10 14 16 18 19 21 34 40 54 56 57 58 60 62 77 82 91 107 154 162 163 164 179 185 190 192 200 202 211 214 231 234 270 288 290 304 311 331 337 342 363 369 398 431 MOULDING COMPOUND, 58 170 288 342 380 391 400 453 MOULDING FAULT, 248 MOULDING PRESSURE, 47 190 248 250 307 326 414 MOULDMAKING, 57 102 288 317 331 348 MOULDS OF POLYMERS, 12 26 45 62 138 153 164 175 182 190 194 237 272 288 305 320 331 344 393 410 MULTI-CAVITY MOULD, 204 248 250 311 342 385 MULTI-COMPONENT, 2 9 26 64 79 105 132 MULTI-MATERIAL MOULDING, 2 102 105 MUTAGEN, 389 399 MYOSITIS, 297 NANOSTRUCTURE, 231
© Copyright 2001 Rapra Technology Limited
N NATURAL RUBBER, 35 64 146 149 234 243 304 NEOPRENE, 42 149 161 NERVE REGENERATION, 283 NIP GAP, 34 NIPPLE, 37 163 224 227 NITRILE RUBBER, 102 105 149 219 NITROSAMINE, 304 407 NITROSAMINE-FREE, 37 NOISE REDUCTION, 319 367 NON-ALLERGENIC, 173 NON-RETURN VALVE, 273 NON-STICK, 7 NON-TOXIC, 25 173 229 303 311 NOZZLE, 193 234 235 243 260 NUCLEAR MAGNETIC RESONANCE, 174 216 217 245 253 267 280 420 NYLON, 14 25 60 64 89 105 125 132 150 161 211 238 255 410
O O-RING, 77 95 269 303 327 368 386 ODOUR-FREE, 303 OFF-THE-ROAD VEHICLE, 124 OFFICE EQUIPMENT, 89 219 306 OFFSHORE APPLICATION, 185 352 OIL PAN GASKET, 219 269 383 392 412 OIL RESISTANCE, 11 60 77 148 159 191 202 219 249 269 287 291 380 383 385 445 OIL SEAL, 202 347 OLIGOMER, 304 309 328 329 346 363 423 447 ONE-COMPONENT, 14 26 138 157 159 250 311 313 342 394 400 408 409 422 439 446 449 450 453 OPTIC FIBRE, 379 OPTICAL APPLICATION, 12 16 21 36 57 264 277 OPTICAL PROPERTIES, 14 21 22 25 56 131 141 185 194 202 212 218 229 237 248 263 292 293 295 303 312 331 353 379 OPTOELECTRONIC APPLICATION, 36 386 ORGANOLEPTIC PROPERTIES, 213 ORGANOSILICONE POLYMER, 9 16 21 27 37 38 40 43 55 59
159
Subject Index
66 70 75 78 84 85 86 87 88 90 93 94 97 103 110 113 114 121 122 123 124 126 134 135 140 142 143 151 154 156 166 168 179 195 197 199 203 205 206 207 208 209 210 220 226 230 232 233 238 OUTGASSING, 77 121 126 331 437 OVEN CURING, 25 26 185 200 202 OVERMOULDING, 11 60 64 65 89 105 150 238 OXIDATION, 141 217 278 314 437 OXIDATION RESISTANCE, 26 185 293 OXIDATIVE DEGRADATION, 141 217 278 314 437 OXIME, 450 OXYGEN INDEX, 249 OZONE RESISTANCE, 26 35 65 248 250 293 311 343 363 380 437
P PACKAGING, 86 270 400 408 PAD, 228 345 PAINT, 237 390 408 448 PAINTABILITY, 90 PAPER COATING, 25 PARTING LINE, 45 194 331 PASTE, 248 250 295 422 PATENT, 176 179 192 376 382 PEEL STRENGTH, 64 90 105 261 440 PELLET, 54 211 PENTASILICIC ACID, 216 PERFLUOROELASTOMER, 77 PERMEABILITY, 21 138 177 264 267 418 419 PERMITTIVITY, 371 PEROXIDE, 1 26 101 138 157 159 185 200 218 222 241 250 292 295 342 363 377 392 446 449 PEROXIDE VULCANISATION, 46 67 138 159 163 185 200 218 250 271 291 292 295 396 PHARMACEUTICAL APPLICATION, 25 98 131 184 188 221 267 293 301 340 402 416 PHENYLSILICONE RESIN, 381 PHOTOCONDUCTIVITY, 312 PHOTOCROSSLINK, 14 107 182 346 442 PHOTODEGRADATION, 312 437
160
PHOTOINITIATOR, 312 346 442 PHOTOLITHOGRAPHY, 71 141 PHOTORESIST, 12 141 277 312 442 PHOTOSENSITISER, 59 346 PHYSICAL PROPERTIES, 45 58 69 112 177 222 239 241 244 364 384 394 417 426 434 439 445 453 PHYSICOCHEMICAL PROPERTIES, 183 221 300 PHYSICOMECHANICAL PROPERTIES, 68 152 PIGMENT, 14 194 248 249 250 255 295 311 PIPE, 352 PIPE LINING, 149 PISTON, 2 150 PLASMA TREATMENT, 21 141 419 PLASTICISATION, 104 385 PLASTICISER, 127 131 185 255 304 408 PLATELET ADHESION, 39 PLATINUM, 1 3 10 26 33 51 88 94 95 97 138 157 185 195 202 232 241 250 304 331 342 346 377 434 PLATINUM CURING, 46 241 271 PLUG, 27 67 PLUNGER, 385 401 POLYADDITION, 64 129 143 213 423 POLYAMIDE, 14 25 60 64 89 105 125 132 150 161 211 238 295 314 410 448 POLYBUTYLENE TEREPHTHALATE, 60 64 105 229 238 261 POLYCARBONATE, 14 237 238 261 POLYCARBORANE SILOXANE, 371 POLYCARBOSILANE, 56 155 312 POLYCARBOSILOXANE, 72 POLYCHLOROPRENE, 42 149 161 249 394 POLYCONDENSATION, 85 143 191 423 435 446 POLYCYCLOSILOXANE, 85 POLYDIBUTYLPHENYLSILANE, 36 POLYDIETHYLSILOXANE, 420 POLYDIHEXYLSILANE, 312 POLYDIMETHYL SILOXANE, 4 21 22 31 32 92 98 101 103 115 131 137 141 178 183 186 197
200 202 203 213 214 216 217 221 225 231 245 246 256 267 280 283 292 293 299 300 309 316 397 428 POLYDIMETHYLPHENYLSILOXANE, 371 435 POLYEPOXIDE, 12 19 138 POLYETHYLENE, 14 128 237 249 287 314 344 377 394 POLYETHYLMETHYLSILOXANE, 418 POLYFLUOROSILOXANE, 21 POLYIMIDE, 177 265 417 448 POLYMERISATION, 4 56 78 85 90 129 155 184 272 293 312 363 390 425 POLYMETHYL METHACRYLATE, 14 231 278 305 344 POLYMETHYLOCTYLSILOXANE, 418 POLYMETHYLPHENYL SILOXANE, 293 POLYMETHYLPHENYLSILANE, 36 212 354 POLYMETHYLPHENYLSILOXANE, 418 POLYMETHYLPHENYLSILYLENE, 406 POLYMETHYLPROPYLSILOXANE, 418 POLYMETHYLSILOXANE, 152 380 433 POLYMETHYLTRIFLUOROPROPYLSILOXANE, 418 POLYMETHYLVINYL SILOXANE, 396 POLYORGANOSILOXANE, 4 9 16 21 22 27 31 32 37 38 40 43 55 59 66 75 78 84 85 86 87 90 92 93 94 97 98 101 103 110 113 114 115 121 122 123 124 126 134 135 140 142 143 151 154 156 165 166 168 179 195 197 199 203 205 206 207 208 209 210 220 226 230 232 233 238 285 POLYPHENYL SILOXANE, 380 POLYPHENYLENE ETHER, 64 238 POLYPHENYLENE OXIDE, 238 POLYPHENYLENE SULFIDE, 400 POLYPHENYLENE VINYLENE, 354 POLYPHENYLMETHYL SILOXANE, 437 447 POLYPROPYLENE, 237 265 349
© Copyright 2001 Rapra Technology Limited
Subject Index
377 POLYSILETHYLENESILOXANE, 418 POLYSILHEXYLENE SILOXANE, 418 POLYSILOXANE ACRYLATE, 21 POLYSILOXANE-URETHANE, 21 POLYSTYRENE, 87 133 237 238 245 293 POLYSULFIDE, 14 408 422 POLYTETRAFLUOROETHYLENE, 35 82 POLYTRIFLUOROPROPYLMETHYLSILOXANE, 437 POLYURETHANE, 14 21 30 52 99 100 133 134 136 138 146 152 192 206 226 231 268 305 306 314 318 319 325 328 331 341 350 351 352 358 381 389 390 394 408 421 422 POLYURETHANE ELASTOMER, 138 139 239 389 POLYVINYL CHLORIDE, 6 14 100 146 249 268 314 POLYVINYL SILOXANE, 14 53 POLYVINYLPYRROLIDONE, 370 POROSITY, 3 168 172 218 283 331 361 POST CURING, 26 64 105 185 200 202 218 248 304 331 342 363 POST FORMING, 319 POT LIFE, 89 POTTING, 59 POTTING COMPOUND, 293 380 400 417 453 POWER TRANSMISSION, 137 PRECIPITATED SILICA, 292 PRECISION MOULD, 190 202 326 405 PRECURING, 200 PRECURSOR, 13 16 312 426 PREFORM, 117 PREHEATING, 2 331 PREPREG, 400 PRESSURE, 34 104 157 190 193 200 202 227 246 269 292 294 307 309 310 344 428 PRESSURE CONTROL, 229 PRESSURE RESISTANCE, 218 269 PRESSURE SENSITIVE, 121 126 275 372 377 380 423 429 434 435 PRICE, 7 11 77 102 179 341 400 445
PRIMER, 421 422 435 PRIMERLESS, 65 PRINTED CIRCUIT, 380 390 400 PRINTING, 116 238 442 PROCESSABILITY, 18 48 65 77 100 118 246 381 PROCESSING, 12 18 25 26 46 67 79 91 99 120 131 148 163 169 181 185 192 207 237 241 244 250 251 255 257 263 295 303 311 348 353 364 376 379 382 401 416 446 PROCESSING AID, 304 PRODUCT ANNOUNCEMENT, 9 13 27 102 156 176 180 192 196 243 257 284 306 330 337 339 349 355 362 369 373 378 382 386 387 390 400 404 408 409 411 421 436 PRODUCT DESIGN, 28 119 189 234 237 257 294 331 PRODUCT DEVELOPMENT, 11 18 60 126 237 PRODUCTION, 148 180 255 453 PRODUCTION COST, 18 150 224 235 237 243 248 342 PRODUCTION RATE, 60 263 305 310 PRODUCTIVITY, 54 150 175 179 220 243 248 257 342 445 PROFILE, 151 185 292 359 363 PROSTHESIS, 14 26 57 61 122 142 152 167 217 236 250 286 296 344 356 361 366 389 PROTECTIVE CLOTHING, 25 263 303 311 313 353 364 378 PROTECTIVE COATING, 43 187 390 426 453 PROTEIN, 86 217 283 293 389 PROTOTYPE, 26 83 141 175 180 193 194 237 320 325 331 341 344 393 PSEUDO GEL, 142 PULL STRENGTH, 16 PUMP, 229 235 271 PURITY, 77 271 329 453 PUTTY, 170 254 302 337 398 PYROGENIC, 157 PYROLYSIS, 177 312 407 426
Q QUALITY, 54 126 132 150 168 234 241 262 263 273 310 353 364 378 386 413 445 QUARTZ, 14 162 441 QUICK COLOUR CHANGING, 2 QUICK MOULD CHANGING, 326
© Copyright 2001 Rapra Technology Limited
R RACING CAR, 412 RADIATION CROSSLINKING, 59 68 103 250 396 434 449 RADIATION DEGRADATION, 131 RADIATION RESISTANCE, 313 343 352 RADIATION STERILISATION, 7 131 RADIATOR, 159 RADIOIMMUNOASSAY, 268 RAILWAY, 72 375 408 RAPID PROTOTYPING, 26 83 305 RAPID TOOLING, 83 237 REACTION INJECTION MOULDING, 251 341 RECYCLING, 161 200 255 263 282 303 311 349 353 364 377 385 RED IRON OXIDE, 157 REFRACTIVE INDEX, 45 312 REFRIGERATOR, 238 REGULATION, 77 242 304 322 390 416 REINFORCED PLASTIC, 14 19 142 150 153 183 196 210 238 240 245 317 319 323 335 336 337 360 374 382 385 391 400 410 417 REINFORCED RUBBER, 13 50 106 158 295 357 REINFORCEMENT, 58 150 256 425 444 446 REJECT RATE, 126 RELEASE AGENT, 40 58 82 113 140 372 RELEASE COATING, 372 377 428 429 434 RELEASE PROPERTIES, 168 218 377 423 REPLICATION, 12 164 231 REPRODUCIBILITY, 98 104 193 RESIDENCE TIME, 200 309 RESILIENCE, 108 131 218 243 342 RESISTIVITY, 65 127 RESTORATION, 138 443 RETARDER, 53 REVIEW, 9 43 46 50 70 78 80 90 91 94 102 120 122 127 129 139 140 144 145 146 148 149 155 177 187 241 245 253 258 264 277 293 297 298 299 316 328 346 351 352 365 369 372 376 377 381 388 389 394 395 396
161
Subject Index
406 407 414 415 417 418 419 420 421 422 423 425 426 427 428 429 430 431 432 433 434 435 436 437 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 RHEOLOGICAL PROPERTIES, 10 14 18 25 26 49 51 53 65 77 82 104 105 115 119 138 142 157 160 161 173 184 191 200 213 220 246 248 250 292 293 307 309 310 316 331 342 363 380 417 420 425 RHEOMETRY, 94 157 241 246 292 310 342 401 RHEUMATISM, 297 RIFAMPICIN, 221 RIGID, 52 64 105 190 394 RING-OPENING POLYMERISATION, 85 328 406 446 451 ROBOT, 2 102 150 193 229 234 325 327 ROCKER COVER, 269 321 ROLLER, 34 139 160 218 219 227 306 343 ROOFING, 394 ROOM TEMPERATURE VULCANISATION (RTV), 25 26 38 48 81 94 138 159 164 191 201 238 250 255 256 313 368 380 381 392 423 439 443 444 446 449 ROTATING TABLE, 150 385 ROTATIONAL MOULDING, 64 105 360 RUBBERISED FABRIC, 313 RUNNER, 193 307 331 RUPTURE, 122 142 428
S SAFETY, 271 322 331 352 362 364 407 SAG FACTOR, 201 SALES, 11 102 156 179 223 226 368 445 SALICYLIC ACID, 188 SALIVA, 14 236 SALT FOG RESISTANCE, 189 295 SANITARYWARE, 422 SCANNING ELECTRON MICROSCOPY, 4 61 133 172 177 186 198 221 245 308 315 366 SCORCH, 64 105 200 342 SCRAP, 150 200 263 269 303 311
162
342 SCRAP REDUCTION, 150 248 250 329 342 SCRATCH RESISTANCE, 331 SCREW, 160 193 235 246 273 309 SCREW SPEED, 200 246 309 SEAL, 9 15 18 27 35 38 60 76 77 81 84 95 99 119 121 123 126 130 150 159 179 181 185 202 211 219 223 227 235 250 269 273 291 293 294 295 303 306 311 321 327 336 347 352 353 362 363 367 374 383 385 386 392 SEALANT, 6 7 38 40 48 65 81 90 114 124 127 226 255 327 339 352 365 368 394 395 404 408 422 430 437 438 439 450 453 SEALING, 9 84 324 343 352 383 SEALING STRIP, 108 SEAT, 14 SELF-ADHESIVE, 11 25 26 65 89 SELF-EXTINGUISHING, 238 248 SELF-LUBRICATING, 15 60 159 185 248 250 263 303 311 SEMI-FLEXIBLE, 62 SEMICONDUCTOR, 5 75 77 312 329 380 SENSITISATION, 131 SENSOR, 32 159 275 SERVICE LIFE, 6 28 35 166 173 175 189 218 219 269 272 291 331 338 347 SERVICE TEMPERATURE, 77 SHEAR, 84 89 124 157 200 246 292 294 310 420 SHEAR RATE, 184 200 246 292 307 310 SHEATH, 62 147 SHEET, 55 200 SHEET MOULDING COMPOUND, 14 SHELF LIFE, 89 218 342 SHELL, 152 195 SHIELDING, 337 SHIP, 72 SHOCK ABSORBER, 159 284 375 392 SHORE HARDNESS, 107 129 182 SHORT PRODUCTION RUN, 320 341 SHOT CAPACITY, 150 374 SHOT WEIGHT, 193 273 SHOWER, 60 422 SHRINKAGE, 12 14 90 157 162 272 305 329 331 348 398 SILANOL GROUP, 85 138 211 SILICA, 14 33 58 92 95 106 112
131 138 157 162 167 185 202 217 218 219 222 245 251 256 276 292 363 391 392 395 408 423 441 444 446 SILICON CARBIDE, 312 426 SILICON-29, 217 SILICONE COPOLYMER, 21 88 115 264 351 387 444 452 SILICONE OIL, 15 25 26 80 213 363 392 395 SIMULATION, 105 132 178 246 292 304 310 325 SINGLE-COMPONENT, 14 26 138 157 159 SLIP, 246 SMALL-COMPONENT, 159 193 248 263 303 311 353 364 SMOKE, 26 185 249 352 381 SNAP-FIT, 77 SOCKET, 344 SOFT CONTACT LENSES, 21 SOFT-TOUCH, 103 SOFTWARE, 83 180 220 294 307 325 SOLAR CELL, 417 SOLUBILITY, 21 177 217 293 309 363 425 SOLUTION CASTING, 360 SOLVENT, 21 69 155 356 443 SOLVENT EXTRACTION, 69 200 304 SOLVENT RESISTANCE, 148 356 SOLVENTLESS, 25 161 377 390 408 434 SOUND ATTENUATION, 196 SOXHLET EXTRACTION, 101 200 SOYABEAN OIL, 195 SPACE APPLICATION, 417 SPARK PLUG, 219 235 250 392 SPIN CASTING, 175 SPORTS EQUIPMENT, 194 311 SPRAYING, 62 288 295 357 408 SPREADING, 352 SPRUE, 331 SPRUELESS, 9 STABILISER, 157 250 293 304 STABILITY, 21 46 90 121 126 129 148 159 185 202 205 352 357 381 395 STANDARD, 34 93 96 157 161 262 304 319 324 332 333 334 335 353 362 365 377 383 STAPHYLOCOCCUS, 236 278 STATIC, 218 375 STATIC MIXER, 305 311 STATISTICS, 7 35 40 50 77 90 102 118 148 161 179 181 185 226
© Copyright 2001 Rapra Technology Limited
Subject Index
255 257 368 413 445 STEAM CURING, 26 STEEL, 295 422 STEERING WHEEL, 11 STERILISATION, 7 131 239 311 389 STICK-SLIP PROPERTIES, 440 STRAIN, 200 236 294 295 STRENGTH, 17 50 53 65 94 129 STRESS, 28 50 92 189 246 283 294 310 329 379 437 STRESS RELAXATION, 114 219 269 310 383 STRESS-STRAIN PROPERTIES, 174 200 294 SUBCUTANEOUS, 399 SULPHUR VULCANISATION, 304 SURFACE CRACKING, 292 SURFACE DEGRADATION, 137 SURFACE ENERGY, 65 103 137 189 SURFACE FINISH, 87 103 218 237 248 273 SURFACE PROPERTIES, 20 61 64 68 71 105 128 172 186 206 214 218 239 292 300 425 437 453 SURFACE TREATMENT, 21 41 89 135 211 237 238 295 331 363 370 SURFACTANT, 53 90 103 293 SURGICAL APPLICATION, 4 14 31 100 111 122 131 134 135 146 152 167 195 198 199 216 236 239 242 253 259 266 279 296 300 318 338 344 350 358 366 387 389 397 407 409 411 416 425 431 435 444 445 SURGICAL TUBING, 100 131 250 384 SWELLING, 21 69 90 101 157 188 200 202 213 256 287 291 295 310 356 380 383 SWITCH, 11 SYNTHESIS, 85 155 184 197 258 264 316 328 346 351 357 376 406 424 426 439 444 446 447 SYNTHETIC LEATHER, 325 SYNTHETIC RUBBER, 90 96 101 120 165 SYRINGE, 115 263 303 311 353
T TACK, 17 114 228 342 345 TAKE-OFF SYSTEM, 273 TAKEOVER, 40 223 368
TALC, 162 TAPE, 96 377 TEAR STRENGTH, 25 53 63 65 77 93 131 138 161 162 167 185 202 218 228 248 249 250 269 291 295 331 342 345 433 444 TEAT, 37 163 224 227 304 311 353 TELECOMMUNICATIONS APPLICATION, 194 238 336 TELESCOPE, 417 TELEVISION, 194 222 238 TEMPERATURE CONTROL, 2 104 158 193 273 303 342 TEMPERATURE DEPENDENCE, 47 50 130 212 246 TEMPERATURE RANGE, 35 65 173 229 255 258 319 336 TEMPERATURE RESISTANCE, 67 91 189 364 377 381 394 TEMPLATE, 107 182 283 TENSILE PROPERTIES, 4 21 24 65 69 95 101 124 125 129 157 167 174 200 202 205 218 219 228 235 250 291 312 342 345 363 392 394 408 422 433 441 444 445 TEST EQUIPMENT, 93 94 178 325 386 TEST METHOD, 65 68 93 103 137 180 189 304 325 TESTING, 65 68 93 94 103 137 178 180 189 217 243 244 262 271 304 325 333 362 365 367 386 389 390 394 395 398 399 407 413 416 432 434 440 TETRAMETHYLDISILOXANE DIOL, 216 TEXTILE, 25 140 257 378 364 THERMAL CONDUCTIVITY, 10 25 218 246 THERMAL DEGRADATION, 65 177 202 219 389 392 394 400 413 453 THERMAL EXPANSION, 248 317 329 331 380 THERMAL INSULATION, 55 118 319 381 394 THERMAL PROPERTIES, 25 26 50 56 98 104 131 161 218 245 246 247 248 258 293 295 307 309 317 331 363 379 380 402 425 453 THERMAL STABILITY, 7 11 14 25 26 46 48 50 60 64 77 90 105 121 126 129 131 138 148 159 169 179 185 194 202 218 219 227 229 235 248 250 258 263 269 290 291 293 295 303 311
© Copyright 2001 Rapra Technology Limited
313 329 343 353 363 380 385 391 392 412 422 437 445 448 453 THERMOFORMING, 14 THERMOLYSIS, 3 312 407 THERMOPLASTIC ELASTOMER, 62 64 102 127 223 235 304 THICK-WALL, 104 THICKNESS, 21 25 105 188 237 239 326 331 383 THICKNESS CONTROL, 237 THIN FILM, 42 44 168 THIN-WALL, 104 105 238 331 357 THROMBECTOMY, 176 THROMBORESISTANCE, 183 TIEBARLESS, 234 243 326 TIN COMPOUND, 61 129 201 250 302 331 337 434 TISSUE EXPANDER, 308 TISSUE RESPONSE, 217 239 283 384 TITANIUM COMPOUND, 59 162 278 295 415 426 TOGGLE, 102 248 326 TOLERANCE, 83 104 235 237 294 TOOLING, 19 60 153 227 237 317 TOOTH RESTORATION, 14 TOXICITY, 14 25 131 143 185 192 249 263 271 303 304 352 358 362 381 389 390 396 407 438 TOYS, 194 237 TRACKING RESISTANCE, 219 TRADE NAME, 2 14 25 26 131 159 193 202 219 238 249 250 263 313 353 389 392 405 TRAFFIC CONTROL, 275 TRANSDERMAL, 98 TRANSFER MOULDING, 91 163 185 329 342 380 400 453 TRANSLUCENT, 25 272 TRANSMISSION FLUID, 202 291 TRANSPARENCY, 21 103 107 131 141 185 194 202 229 232 237 248 257 263 264 289 292 303 305 353 364 TRANSPORT APPLICATION, 362 381 TRANSPORT PROPERTIES, 298 354 TREND, 100 103 339 TRIMETHOXYVINYLSILANE, 408 TROUBLESHOOTING, 160 TRUCK, 124 413 TUBING, 7 100 131 162 185 250
163
Subject Index
252 262 271 310 343 352 363 387 TUMOUR, 337 399 TURBOCHARGER HOSE, 413 TWIN-SCREW EXTRUDER, 230 246 309 TWO-COMPONENT, 9 11 15 26 42 47 53 65 89 105 125 138 150 157 159 161 179 202 224 227 229 238 248 250 263 303 305 310 311 313 321 325 364 374 378 385 393 394 422 439 446 449 453
U UNDER-THE-BONNET APPLICATION, 35 77 89 159 166 185 202 219 269 291 294 321 327 367 380 385 392 400 427 UNDERWATER APPLICATION, 158 UNSATURATED POLYESTER, 138 335 374 385 UV CURING, 14 25 238 372 377 379 UV RADIATION, 137 346 UV RESISTANCE, 35 185 189 226 250 311 377 381 394 408
V VACUUM, 190 229 309 VACUUM BAG MOULDING, 410 VACUUM CASTING, 26 194 237 320 331 341 393 VACUUM FORMING, 14 190 VACUUM MOULD, 248 VALVE, 185 385 VALVE COVER, 219 269 374 385 412 VANDAL PROOF, 219 VARNISH, 103 140 VASCULAR PROSTHESIS, 268 VEHICLE DOOR, 238 VEHICLE ENGINE, 159 219 269 385 VEHICLE IGNITION, 219 VEHICLE LIGHT, 238 VEHICLE RADIATOR, 159 VEHICLE SPOILER, 408 VEHICLE SUSPENSION, 375 VENTING, 49 190 309 331 VERTICAL MACHINE, 2 102 349 VIBRATION DAMPER, 159 293 367 392
164
VINYL GROUP, 110 200 202 211 VISCOELASTIC PROPERTIES, 213 286 292 310 VISCOSITY, 10 14 18 25 26 49 51 53 65 77 82 101 104 115 119 138 157 160 173 184 191 200 213 246 248 250 255 292 293 307 310 331 363 380 VOICE PROSTHESIS, 61 236 366 VOID, 112 331 VOID-FREE, 341 VOLATILE, 85 110 309 438 VOLATILITY, 269 293 304 438 VOLUME RESISTIVITY, 249 336 371 VULCANISATION, 2 25 26 46 67 78 79 101 105 106 131 138 150 159 162 163 171 181 185 193 194 200 202 218 219 248 249 250 260 263 292 295 301 303 304 307 310 311 313 331 342 348 353 359 363 380 383 392 396 424 425 444 449 VULCANISATION TIME, 2 6 26 60 129 131 138 150 185 200 202 229
W
WEATHERING, 6 72 77 249 255 290 343 380 394 395 422 437 443 WEIGHT LOSS, 157 293 309 398 WEIGHT REDUCTION, 161 234 243 336 WETTABILITY, 20 21 53 65 109 WETTING, 92 103 167 264 WINDOW, 88 138 238 362 422 WINDSCREEN WIPER BLADE, 35 82 159 WIRE, 73 112 249 332 334 368 445 453 WIRING HARNESS, 319 WOOD FINISH, 103 WORK SURFACE, 408
X X-RAY CONTRAST MATERIAL, 119
Y YIELD, 155 246 426 YOUNG’S MODULUS, 4 5 21 84 167 271 292 294 379
WALL SLIP, 246 292 WALL THICKNESS, 18 64 105 310 331 341 WASHER, 150 383 WASHING, 137 304 WASTE, 173 200 263 271 303 311 353 WATER, 20 85 188 217 236 263 303 443 WATER ABSORPTION, 65 379 421 422 437 443 448 453 WATER EXTRACTION, 304 WATER PERMEABILITY, 138 423 443 WATER REPELLENT, 72 159 187 448 WATER RESISTANCE, 20 21 60 72 293 338 421 422 437 443 448 WATERPROOFING, 27 138 187 423 WAX, 58 110 138 WEAR RESISTANCE, 14 34 42 119 145 161 218 306 WEATHER RESISTANCE, 6 7 72 77 226 255 290 348 352 381 394 395 422 WEATHER STRIPPING, 88 219 233 367
© Copyright 2001 Rapra Technology Limited
