The effects of compounding variables on the reversion process in the sulphur vulcanization of natural rubber

Abstract

The effect of several compounding ingredients on the reversion of accelerated sulphur vulcanization of natural rubber (NR) has been examined. Accelerators which normally provide fast cures are found to cause more severe reversion than slower accelerators. MgCO 3, CaCO 3, silica and China clay all increase reversion but the severity depends on the accelerated system employed. Generally, antidegradants increase reversion, the effect being more prominent with 2-mercaptobenzimidazole. Reversion appears to be typical only for the polyisoprene structure and it can be overcome by blending with SBR at appropriate ratios.