Comparative Study on Cure, Mechanical and Dynamic-Mechanical Properties of Natural Rubber Compounds Formulated with DIXP, TBzTD, ZBeC and TBBS Accelerators

Today, it is obligatory to replace nitrosamine releasing traditional accelerators owing to the various health, safety and environment regulations and surviving with safe alternative is a one of the key challenges in the rubber industry. In this work four groups of commercially available nitrosamine free/safe accelerators were selected, i,e., diisopropyl xanthogen polysulfide (DIXP), tetrabenzyl thiuramdisulfide (TBzTD), zinc dibenzyl dithiocarbamate (ZBeC) and N-tert-butyl-2-benzothiazole sulfenamide (TBBS). The effect of accelerator type on cure, crosslink density, physico-mechanical and dynamic-mechanical properties of efficient sulfur vulcanized natural rubber (NR) compounds was investigated. Results reveal that accelerator type does not only affect the cure characteristics, but also has a great impact on physical and mechanical properties, DIXP possess the least modulus and strength properties while providing satisfactory optimum cure time for the vulcanization compared to the TBBS accelerator. Improvement in mechanical properties is observed in the order ZBeC, TBzTD, TBBS and corroborates well with the crosslink density. ZBeC and TBzTD show relatively higher hardness, storage modulus and lower hysteresis in the rubbery region indicating different microstructure arrangement compared to commonly use of non-regulated nitrosamine safe TBBS accelerated vulcanizates.