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 size distribution, on the brittle ductile transition of poly(vinyl chloride) (PVC)/nitrile rubber (NBR) blends with the morphology of well-dispersed NBR particles have been studied. PVC has been supertoughened with 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 critical particle size and critical rubber volume fraction to rubber particle size distribution are discussed. It is argued that rubber particle size 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 distribution favours the rubber toughening of PVC. (C) 1998 Elsevier Science Ltd. All rights reserved.