Model Vulcanization of EPDM Compounds—Part I: Structure Determination of Vulcanization Products from Ethylidene Norbornane

Abstract

Abstract Vulcanization of ENBH (C9H14), a model for ENB containing EPDM rubber, with a system consisting of zinc oxide, stearic acid, sulfur, TMTD, and MBT at 140°C for 1 h yields slightly more than 30 different crosslinked products C9H13-Sn-C9H13 where n=2,3,4, and 5. In all of the products, the original ENBH structure is maintained (no shift of the double bond) and attachment of the sulfur bridge occurs only at the two allylic positions 3 and 9. Monosulfides (n=1) are probably also formed but no structures could be determined. Only small amounts of the MBT-Sn-C9H13 coupling products and noncrosslinked cyclic sulfides are formed.