Effects of trans-polyoctylene rubber (TOR) on the properties of NR EPDM blends

trans-Polyoctylene rubber (TOR) was melt blended with an incompatible NR/EP DM (70/30) blend. Mixing torque and temperature were reduced as TOR was add ed to NR/EPDM blend. The curing characteristics of the blend were affected as TOR participated in vulcanization and became a part of network. A scanni ng electron micrograph demonstrated that addition of TOR improved the compa tibility of the blend and thereby led to a finer phase morphology. The ozon e resistance of the blends was determined in terms of a critical stress-str ain parameter. The critical stored energy density for ozone cracking was si gnificantly enhanced for the TOR containing rubber blend. It was believed t hat the improvement in ozone resistance arised from finely dispersed ozone- resistant EPDM particles in the blend. TOR caused an improvement in dynamic properties and an increase in tensile modulus, but a decrease in tensile s tress and elongation at break of the rubber blend. (C) 1999 John Wiley & So ns, Inc.