Preparation and Vulcanization of Unsaturated Acrylic Elastomers

Ethyl acrylate was copolymerized with small proportions of eleven dienes, eleven polyolefinic esters, and six polyolefinic ethers in an attempt to prepare olefin-containing acrylic elastomers that would vulcanize readily, yielding products having improved rubbery characteristics. In general, the resulting copolymers were insoluble in organic solvents, presumably because of cross-linkage. Acrylonitrile and dodecanethiol appeared beneficial in the copolymerization of ethyl acrylate with polyolefinic esters, but of questionable value in the diene polymerizations. The best vulcanizates from the standpoint of tensile strength and elongation were obtained from an ethyl acrylate-acrylonitrile-vinyl ether copolymer. Some preparations of this copolymer, however, had a tendency to pit and bubble during vulcanization. Isoprene, piperylene, and 2,3-dimethylbutadiene were more suitable for preparing vulcanizable ethyl acrylate copolymers than the other dienes studied; their vulcanizates had moderately high tensile strengths and elongations. Some of the dimethylbutadiene-ethyl acrylate copolymers were soluble. Crotyl acrylate and geranyl acrylate, when copolymerized with ethyl acrylate, yielded copolymers that gave vulcanizates having moderately high tensile strengths and elongations ranging from 300 to 400 per cent. The physical properties of the vulcanizates prepared from unsaturated acrylic copolymers were not superior to those of the chloropropyl acrylate and chloroethyl vinyl ether products described previously.