OIL-RESISTANCE STUDIES OF DYNAMICALLY VULCANIZED POLY(VINYL CHLORIDE)EPOXIDIZED NATURAL-RUBBER THERMOPLASTIC ELASTOMER

Dynamically vulcanized poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) thermoplastic elastomers (TPEs) were prepared with a Brabend er plasticorder coupled with a mixing attachment by melt mixing. The b lends were prepared at 150 degrees C at a rotor speed of 50 rpm. Curat ives concentration was steadily increased from 0 to 1 phr in order to study the vulcanization effect on the plasticized blend. The effective ness of the dynamic vulcanization was indicated by the Brabender plast ograms. The properties investigated include mass swell, tensile streng th, elongation at break, modulus at 100% elongation (M100), tear stren gth, and hardness. The PVC/ENR samples were exposed to two types of en vironments, namely, air and oil under otherwise identical conditions. The effect of oil and thermooxidative aging on the mechanical properti es were characterized at room temperature and 100 degrees C. It was fo und that at ambient temperature the samples immersed in oil possessed similar properties to those that were exposed to air. Significant enha ncement in mechanical properties were observed for both environments a t 100 degrees C. This has been attributed to the increase in crosslink density which was manifested by a steady reduction in percent mass sw ell with increased sulfur loading. The excellent mechanical behavior o f the PVC/ENR TPEs even after immersing the samples in oil at 100 degr ees C has provided a good indication of the oil resistance of the mate rials. (C) 1998 John Wiley & Sons, Inc.