Rubbers silicone rubber

Polymerisation resulting from a chemical reaction involving condensation. The synthetic elastomers produced by condensation polymerisation include polysulphide rubbers, silicone rubbers and the ester and isocyanate rubbers. 

A convenient term for any material possessing the properties of a rubber but produced from other than natural sources. A synthetic version of natural rubber has been available for many years with the same chemical formula, i.e., cis-1,4-polyisoprene, but it has not displaced the natural form. See also Butyl Rubber, Chloroprene Rubber, Ethylene-Propylene Rubber, Nitrile Rubber, Silicone Rubber and Styrene-Butadiene Rubber. 

Ethylene-propylene rubber Fluoro-rubber Hypalon Natural rubber Neoprene rubber Nitrile rubber Polysulphide rubber Polyurethane rubber Silicone rubber Styrene-butadiene rubber (SBR)... 

Figure 2.20 Permeant diffusion coefficient as a function of permeant molecular weight in water, natural rubber, silicone rubber and polystyrene. Diffusion coefficients of solutes in polymers usually lie between the value in natural rubber, an extremely permeable polymer, and the value in polystyrene, an extremely impermeable material [28]...

Property Natural Rubber Butyl Rubber EPDM rubber Chloroprene rubber Nitrile rubber Silicone rubber Chloro sulfon ated polyethylene rubber... 

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

Tubular Applications. Tubular prostheses and related devices include drains, catheters, and shunts, and these are always made from plastic materials such as natural rubber, silicone rubber, polyethylene, polytetrafluoroethylene, or plasticized poly(vinyl chloride). Many of these devices are designed for temporary use, but some permanent devices have been used for replacement of the trachea, ureter, bile ducts, and other body tubelike parts. 

The applications of the rubbers stem from their important properties, which include thermal stabflity, good electrical insulation properties, nonstick properties, physiological inertness, and retention of elasticity at low temperatures. The temperature range of general-purpose material is approximately — 50°C to -l-250°C, and the range maybe extended with special rubbers. Silicone rubbers are, however, used only as special-purpose materials because of their high cost and inferior mechanical properties at room temperature as compared to conventional rubbers (e.g., natural rubber and SBR). 

There is a relatively large range of different types of rubbers that are used in different components in the food industry that can get in contact with the food. The most important of these are natural rubber (NR ds-l,4-polyisoprene), nitrile rubber (i.e., acrylonitrile-butadiene copolymer), ethylene-propylene rubber (EPR), rubbers of ethylene-propylene monomer (EPM) and EPDM, SBR, fluorocarbon rubber, silicone rubber, polybutadiene rubber (BR), polychloroprene rubber, and TPE. In addition, there is the use of rubber blends, i.e., blends of NR and N Rr with SBR [19]. 

Kind (14) has also reported release rates for progesterone when various polymer materials are used (Table IV). Except for nylon, most materials studied have release rates a thousand times lower than that for silicone rubber. Silicone rubber, widely employed in drug-releasing devices because of its high permeability, has been accepted by the medical industry mainly for its excellent... 

Matty polymers may be used for produetion of wire and cable. These include polyethylene, crosslinked polyethylene, chlorosnlfonated polyethylene, ethylene-propylene rubber, polyvinylchloride, bntyl robber, styrene bntadiene rubber, silicone rubber, natural robber, polyisoprene robber, polyurethane, nitrile butadiene rubber, polychloroprene, polysulfone, thermoplastie elastomers, polyimide, and polyamides. Selection of polymer(s) depends on projected conditions of service such as temperature, presence of corrosive liquids, surrounding temperature, quality of insulation, etc. 

Rubber. Silicone rubber can be heat-cured by fairly conventional techniques. It can also be cast and cured at room temperature, producing what is called room-temperature vulcanized (RTV) rubber. 

Examples of vulcanizable elastomers include natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), ethylene-propylene-diene monomer-rubber (EPDM), butyl rubber (HR), polychloroprene or neoprene (CR), epichlorohydrin rubber (ECO), polyacrylate rubber (ACM), millable polyurethane rubber, silicone rubber, and flu-oroelastomers. Examples of thermoplastic elastomers include thermoplastic polyurethane elastomers, styrenic thermoplastic elastomers, polyolefin-based thermoplastic elastomers, thermoplastic polyether-ester (copolyester) elastomers, and thermoplastic elastomers based on polyamides. 

Peroxide Vulcanization of Silicone Rubbers. Silicone rubbers (high-molecular-... 

Natural rubber, silicone rubber Cross link 50... 

Casting is primarily done with thermoset materials, where the initial form of the material is a pure liquid (they are not heated and melted). In this scenario, the resin is at room temperature, but it must be mixed with a curing agent. It is poured into the mold under normal pressure. The molds are commonly made of latex rubber, silicone rubber, or other similar low-cost materials, and can only be used for a limited number of castings. 

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