New Vulcanizing Systems for Ethylene-Propylene Elastomers

Abstract The absence of chemical functionality in ethylene-propylene elastomers precludes crosslinking with conventional rubber vulcanizing agents. It is known that such elastomers can be vulcanized with combinations of sulfur and certain organic peroxides, but the resulting vulcanizates leave something to be desired from the standpoint of tear strength, odor, and peroxide cost. A chemical study of the reaction between isoparaffins, sulfur, and organic peroxides gave results showing that some important alterations must be made of previous views that have been advanced for the vulcanization of saturated hydrocarbon elastomers by peroxides alone. A new reaction scheme is briefly reviewed. In the course of this study, three new classes of substances have been discovered to be effective vulcanizing agents for ethylene-propylene elastomers, and for other rubbers also. The outstanding characteristics which these new agents produce in ethylene-propylene elastomer vulcanizates are excellent tear strength and no objectionable odor. Data are presented on some properties of vulcanizates prepared with these agents.