Cure behavior of EPDM compounds - Influence of different accelerated sulfur systems

The effect of different accelerator/sulfur systems on the vulcanization beh avior of highly filled EPDM compounds was studied. Cure kinetics were studi ed using Moving Die Rheometer (MDR); Chemical and physical crosslink densit ies were estimated by swelling measurements and by thermomechanical analysi s (TMA). In order to evaluate the rate constant of the curing reaction, Cor an's model was used. The activation energy of crosslinking for 4 systems va ries between 71 and 103 kJ/mol. MDR results are in line with crosslink dens ity data. The lowest tan delta in a semi-efficient system occurs with the h ighest crosslink density which is in good agreement with swelling and TMA r esults.