Chemistry of various accelerators in an e-SBR model compound

Sulfur vulcanization was carried out with 5-phenyl hex-2-ene serving as a model of e-SBR. Various accelerators have been used to study and compare the reactivity in a system containing sulfur and activators. Both HPLC and GC-MS analytical tools were used to identify the reaction products. It has been observed that the vulcanization in the presence of N-cyclohexyl-2-benzothiazole sulfenamide (CBS) generates a large amount of 2-marcaptobenzothiazole (MBT), which continuously increases and finally decreases suggesting further participation in vulcanization generating new crosslinks. The sulfenamide, N-cyclohexyl-4,6 dimethyl-2-pyrimidine sulfenamide (CDMPS) behaves different. Although it generates considerable amount of corresponding thiol, (4,6-dimethyl pyrimidine-2-thiol, DMMP) at the beginning of the reaction, no decrease has been observed during the course of further reaction suggesting that the accelerator, DMMP, somehow remains deactivated and therefore no changes in network is feasible. Identical differences exist between bis(2,2′benzothiazyl) disulfide (MBTS) and corresponding bis (4-methyl-2,2′benzothiazyl)disulfide (M-MBTS) in the reaction kinetics.