Structural characterization of vulcanizates. Part VIII. The <i>N</i>‐cyclohexylbenzothiazole‐2‐sulfenamide‐accelerated sulfur vulcanization of natural rubber at 140–180°C. and of synthetic <i>cis</i>‐1,4‐polyisoprene at 140°C

Abstract

Abstract Vulcanization of natural rubber at 140°C. with a CBS‐accelerated sulfur system of conventional type gives rise to a structurally complex network in which the number of sulfur atoms combined per chemical crosslink present increases from 12 to 21 with increasing reaction time. The complexity of the network increases with increasing temperature of vulcanization. Crosslinking of a purified synthetic cis ‐1,4‐polyisoprene proceeds more slowly and yields a slightly more complex network. Despite this overall similarity the natural rubber vulcanizates exhibit considerably higher tensile strengths.