MORPHOLOGY AND ELECTRICAL-PROPERTIES OF CARBON BLACK-FILLED POLY(EPSILON-CAPROLACTONE) POLY(VINYL BUTYRAL) BLENDS/

Electrical properties of poly(epsilon-caprolactone) (PCL)/poly(vinyl b utyral) (PVB) blends containing carbon black (CB) were studied as a fu nction of a small amount of PVB content and a wide range of molecular weight of PVB. For samples with the same CB content, the intensity of positive temperature coefficient (I-PTC, defined as the ratio of peak resistivity to resistivity at room temperature) of the blends was incr eased, with PVB content greatly and molecular weight of PVB weakly. As the band spacings of PCL spherulites in PCL/PVB blends decrease with PVB content and molecular weight of PVB, the changes of the positive t emperature coefficient property are ascribed to the morphological diff erence (i.e., period of twisted lamellae) in the blends. We confirmed our previous conclusion that the origin of the positive temperature co efficient phenomenon is the changes of the distribution of the CB on t he melting of the crystalline phase. (C) 1998 John Wiley & Sons, Inc.