Silicone elastomers nitrile

Some other silicon elastomers include vinyl silicone elastomers, phenyl silicon elastomers, nitrile silicone elastomers, and fluorosilicone elastomers. 

Elastomers The zinc borate is an effective synergist of halogen sources and smoke suppressants in elastomers such as styrene butadiene rubber (conveyor belting, flooring), neoprene (wire and cable, dampening compound, conveyor belt), EPDM and PVC-nitrile foam (insulation foam), and so on.55 It has also been used in halogen-free silicone elastomer and EPDM, EP (in conjunction with ATH or MDH). 

Silicone elastomers are very permeable to gases—generally about 100 times more so than are butyl or nitrile rubbers. 

I, Nitrile elastomer (Perbunan) II, fluorinated elastomer (Viton) III, silicone elastomer. 

Silicone elastomers are unaffected by oxygen and ozone on natural aging. Because of their water-repellency, silicone elastomers are not seriously affected by aqueous solutions of most chemical reagents. They are attacked by strong acids and alkalis. General purpose elastomers are swollen by aliphatic, aromatic and chlorinated hydrocarbons but much improved resistance is shown by nitrile-and fluorine-containing silicones. In general, room temperature-cured materials have lower solvent resistance. 

The best source of known samples of rubbers is to purchase labelled O rings, as one of these will last for quite a long time if carefully used in the burning tests. Natural rubber has quite a distinctive odour when burned everyone must know the smell of burning rubber, it is easily possible to distinguish between this and nitrile or neoprene for instance. Fluoro and silicone elastomers likewise have their own characteristic combustion properties. 

If polypropylene is too hard for the purpose envisaged, then the user should consider, progressively, polyethylene, ethylene-vinyl acetate and plasticised PVC. If more rubberiness is required, then a vulcanising rubber such as natural rubber or SBR or a thermoplastic polyolefin elastomer may be considered. If the material requires to be rubbery and oil and/or heat resistant, vulcanising rubbers such as the polychloroprenes, nitrile rubbers, acrylic rubbers or hydrin rubbers or a thermoplastic elastomer such as a thermoplastic polyester elastomer, thermoplastic polyurethane elastomer or thermoplastic polyamide elastomer may be considered. Where it is important that the elastomer remain rubbery at very low temperatures, then NR, SBR, BR or TPO rubbers may be considered where oil resistance is not a consideration. If, however, oil resistance is important, a polypropylene oxide or hydrin rubber may be preferred. Where a wide temperature service range is paramount, a silicone rubber may be indicated. The selection of rubbery materials has been dealt with by the author elsewhere. ... 

Terpolymers in which the acrylate monomer is the major component are useful as ethylene-acrylate elastomers (trade name Vamac) [Hagman and Crary, 1985]. A small amount of an alkenoic acid is present to introduce sites (C=C) for subsequent crosslinking via reaction with primary diamines (Sec. 9-2d). These elastomers have excellent oil resistance and stability over a wide temperature range (—50 to 200°C). They are superior to nitrile and chloroprene rubbers. Although not superior to silicone and fluorocarbon elastomers, they are less costly uses include automotive (hydraulic system seals, hoses) and wire and cable insulation. 

Tires, natural mbber tubes, and butyl tubes are the main sources of scrap and reclaim (see Elastomers, synthetic-polyisoprene). Specialty reclaim materials are made from scrap silicone, chloroprene (CR), nitrile— butadiene (NBR), and ethylene—propylene—diene—terpolymer (EPDM) mbber scraps (see... 

Fig. 1. SAE J200 Classification system for ASTM No. 3 oil where in volume swell nr = no requirement. EPDM is ethylene—propylene—diene monomer HR, butyl mbber SBR, styrene—butadiene mbber NR, natural mbber VMQ, methyl vinyl silicone CR, chloroprene FKM, fluoroelastomer FVMQ, fluorovinyl methyl silicone ACM, acrylic elastomers HSN, hydrogenated nitrile ECO, epichlorohydrin and NBR, nitrile mbber.

RUBBER (Synthetic). Any of a group of manufactured elastomers that approximate one or more of the properties of natural rubber. Some of these aie sodium polysulfide ( Thiokol ). polychloiopiene (neoprene), butadiene-styrene copolymers (SBR), acrylonitrilebutadiene copolymers (nitril rubber), ethvlenepropylene-diene (EPDM) rubbers, synthetic poly-isoprene ( Coral, Natsyn ), butyl rubber (copolymer of isobutylene and isoprene), polyacrylonitrile ( Hycar ). silicone (polysiloranei. epichlorohy-drin, polyurethane ( Vulkollan ). 

Some typical elastomers are natural rubber, which is gathered from trees, SBR rubber, which is used a lot in motorcar tires, neoprene, as in wet suits and oil seals, EPDM, a general purpose rubber, butyl, a heat-resistant rubber with the ability to keep the air in car tires, nitrile for oil seals, silicones for heat resistance, fluoro-elastomers for chemical resistance, and last but not least, polyurethanes, which cover a number of the above fields. Table 1.1 shows some of the advantages of castable polyurethanes over conventional rubbers. 

BUNA N (nitrile) Aromatic hydrocarbons, dilute acids and bases, silicones, helium hydrogen Halogen compounds, halogenated hydrocarbons (carbon tetrachloride, trichlorethylene), ketones (acetone), nitro compounds, or strong acids Typical color black. Temperature range -50 to 120°C. Easily compressed. Density 1.00. Lowest permeability rates for gases of all elastomers. 0.25... 

Surface treatments consist of washing with solvent, abrading, or, in the most demanding applications, cyclizing with acid. The most common elastomers to be bonded in this way include nitrile, neoprene, urethane, natural rubber, SBR, and butyl rubber. It is more difficult to achieve good bonds with silicones, fluorocarbons, chlorosulfonated polyethylene, and polyacrylate. 

Figure 10-18 presents the GC/MS analysis of a rubber formulation for an elastomeric insulator for devices to replace those that had been characterized after field-aging. In this example, a high quality silicone rubber was selected for inherent resistance to oxidation and UV damage, plus favorable dielectric properties. Figure 10-18 presents the GC/MS analysis of this elastomer, confirming pure silicone rubber and Tinuvin P, a UV absorbing polymer stabilizer. To reduce cost, many suppliers provide silicone rubber components that are often combined with butyl or nitrile rubber to reduce cost. 

A number of manufactured products comprising thermoplastics (polyethylene, polyvinylchloride, polyamides,. ..) or elastomers (natural rubber, nitrile rubber, ethylene propylene rubber, silicones) are processed by cross-linking to improve their performances in insulated electric wires and cables, multilayered films for cooking pouches, shape memory tubes, pressure resistant water pipes, expandable foams, automotive parts exposed to motor... 

Elastomer Natural rubber Butyl rubber Chlorinated Butyl Rubber Nitrile rubber Silicone rubber Hypalon Chloroprene Viton EPDM EVA... 

This field has been reviewed by Parkinson [426]. Common hydrocarbon elastomers (with the exception of butyl rubber), nitrile and acrylic rubbers were found to be as resistant to radiation as silicones, fluorocarbon and polyurethane rubbers. 

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