EFFECT OF MORPHOLOGY ON THE BRITTLE-DUCTILE TRANSITION OF POLYMER BLENDS - 2 - ANALYSIS ON POLY(VINYL CHLORIDE) NITRILE RUBBER BLENDS

The effects of morphological parameters, especially rubber particle si ze distribution, on the brittle ductile transition of poly(vinyl chlor ide) (PVC)/nitrile rubber (NBR) blends with the morphology of well-dis persed NBR particles have been studied. PVC has been supertoughened wi th well-dispersed NBR particles. A master curve of the brittle ductile transition of PVC/NBR blends is obtained by plotting impact strength versus average matrix ligament thickness. The relationships of critica l particle size and critical rubber volume fraction to rubber particle size distribution are discussed. It is argued that rubber particle si ze distribution is one of the morphological parameters dominating the toughness and the toughening mechanisms of PVC/NBR blends, in addition to the average rubber particle size, rubber particle volume fraction and average matrix ligament thickness. A narrow rubber particle size d istribution favours the rubber toughening of PVC. (C) 1998 Elsevier Sc ience Ltd. All rights reserved.