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Peroxides and radiation are the only methods by which crosslinking can be accomplished, and coagents are often required to achieve the required state of cure. Uses. The main use of EVA is in wire and cable applications, although their electrical properties are inferior to those of EPDM. Ethylene/Acrylate Rubbers: Vamac Repeat units General. The terpolymer Vamac, produced by Dupont, exhibits properties generally comparable to those of an acrylate. The introduction of ethylene into the main chain gives low temperature performance similar to that of a polyoctyl acrylate polymer and oil resistance similar to that of a butyl acrylate polymer.

Hence it is a thermoplastic and not a rubber at ambient temperatures. If the regularity of the main chain could be interrupted, and crystallization effectively prevented, a useful elastomer might result. The chlorination of polyethylene is one method by which crystallization can be prevented, and chlorinated polyethylene is commercially available; the degree of chlorination, however, determines how rubbery the modified polymer is. Polymers with a chlorine content of ca. 25% are still relatively crystalline, while those with a chlorine content greater than 40% become increasingly brittle as a result of interaction between the now highly polar polymer chains.

Hydrogenated nitrile rubbers also exhibit much greater resistance to oxidation and extend the useful service temperature range of nitriles up to ca. 150°C. Commercially available grades offer different degrees of hydrogenation, with residual double bonds ranging from ca. 8 to 6%. Nitriles have good resistance to oil, aliphatic and aromatic hydrocarbons, and vegetable oils, but they are swollen by polar solvents such as ketones. The unsaturated main chain means that protection against oxygen, ozone, and UV light is required.