Epoxidized natural rubber as a reinforcement modifier for silica-filled nitrile rubber

Hydrated silicas impart better physical properties to polar rubbers, compared to those of hydrocarbon rubbers. However, to achieve optimum properties silane coupling agents are crucial in such formulations. Epoxidized natural rubber (ENR) in small proportions is used as a reinforcement modifier for silica-filled nitrile rubber (NBR). Two systems of cure were used: N-cyclohexyl-2-benzthiazyl sulfenamide (CBS) alone and in combination with diphenyl guanidine (DPG). In the CBS accelerated system, incorporation of an optimum concentration of about 15% of ENR on total rubber was found to improve technological properties. Addition of a secondary accelerator further improves these properties. Comparable results are obtained with those containing coupling agent and NBR-ISAF. High bound rubber and volume fraction values indicate a high polymer-filler interaction and gel content resulting from the NBR-ENR interaction. Results of this study reveal that ENR could be used as a reinforcement modifier for the NBR-silica system. (C) 2002 Wiley Periodicals, Inc.