Effect of Coagent Concentration on Crosslinking, Physico-Mechanical Properties of the Peroxide-Cured Hydrogenated Acrylonitrile Butadiene Rubber (HNBR)

Hydrogenated acrylonitrile butadiene rubber (HNBR) is a specialty elastomer exhibiting excellent mechanical properties apart from oil resistance. In the present study, fixed concentration of triallyl isocyanurate (TAIC) 3 parts per hundred (pphr)is used as a coagent along with different concentrations of dicumyl peroxide (DCP) at viz 1, 3 5, 7, 9, 11, and 13 pphr were used to crosslink the HNBR. The cure characteristics were obtained from the Moving Die Rheometer (MDR) and compared with heat of reaction(ΔH) data for each of the compositions. The cured sheets were subjected to mechanical properties using a universal testing machine (UTM). Present studies indicate that the crosslinking efficiency of HNBR will significantly increase in terms of rate of crosslinking by 2 times and the magnitude of crosslinking by 5 times with concentration of peroxide. In addition, mechanical properties are reduced beyond 3 phr of DCP in the presence of coagent, indicating additional crosslinking and a faster cure rate in HNBR than peroxide alone. The present paper describes the mechanism behind the observed trends.