The Vulcanization of Rubber under High Pressure

Abstract

Abstract 1. The influence of high pressures (up to 10,000 kg/cm2) on the cure of gum and compounded rubbers and also on the properties of the resulting products was studied. 2. It was demonstrated that high pressure accelerates vulcanization and effects the specific formation of stable carbon-carbon crosslinks. Thus, crosslinked polymers may be prepared without any vulcanizing agents, yet the resulting vulcanizates have excellent properties. New methods were designated for obtaining crosslinked block polymers having stable crosslinks. 3. It was determined that cure depends on the reactivity of the rubber, the type of unsaturation and, most important, the amount of spatially more accessible external double bonds. 4. It was shown that during the cure of rubber compounds under high pressure the participation of sulfur in the formation of the vulcanizate is substantially decreased. In a mixture of SKB rubber and sulfur the dominating reaction is the interaction of molecules of rubber. Functional fillers and softeners do not undergo substantial change. The use of initiators of radical polymerization contributes by leading to ultrarapid vulcanization of rubber. 5. An assumption is stated concerning the mechanism of vulcanizing rubber under high pressure as well as certain questions about the use of high pressure as a new method of producing molded rubber articles.