Effects of interfacial adhesion on the rubber toughening of poly(vinyl chloride) - Part 1. Impact tests

The influence of interfacial adhesion on the impact toughness of poly(vinyl chloride) (PVC)-nitrile rubber (NBR) blends with the morphology of well-di spersed rubber particles has been investigated. The blend containing NBR 18 (NBR with 18 wt% acrylonitrile (AN)) has medium interfacial adhesion stren gth, and exhibits a brittle-ductile transition at a critical matrix ligamen t thickness T-c = 0.059 mu m while the blend containing NBR 26 (NBR with 26 wt% AN) and having stronger interfacial adhesion exhibits the transition a t T-c = 0.041 mu m. The difference can be understood in terms of the deform ation mechanisms. Debonding at the interface of the PVC-NBR 18 blend takes place upon impact, and this induces shear yielding of the matrix. For the P VC-NBR 26 blend, however, no microvoid is formed, so the occurrence of matr ix shear yielding is delayed. In the investigated rubber particle size rang e (0.04 - 0.12 mu m), debonding followed by matrix shear yielding is a much more important toughening mechanism than internal cavitation of rubber par ticles. (C) 2000 Elsevier Science Ltd. All rights reserved.