Studies on rubber-filler interaction in carboxylated nitrile rubber through microhardness measurement

The influence of carbon black filler loading on the microhardness character istics of two types of carboxylated acrylonitrile butadiene rubber (XNBR) v ulcanizates having different (ionic or covalent) crosslinking reaction syst ems has been studied. The microhardness measurement predicts that the rubbe r-filler interaction in the ionic crosslinking system is higher than that i n the covalent crosslinking system. The high hardness values and strong rub ber-filler interaction in the ionic crosslinking system has been explained on the basis of ionic cluster formation for the carboxylate salt in XNBR. T he microhardness measurement result helps to evaluate the rubber-filler int eraction and shows good correlation with the dynamic mechanical result. The theoretical predicted data deviate highly in the ionic crosslinking system , although there is a goad correlation in the covalent crosslinking system. (C) 2001 Elsevier Science Ltd. All rights reserved.