Conductive-filler-filled poly(?-caprolactone)/poly(vinyl butyral) blends. II. Electric properties (positive temperature coefficient phenomenon)

Abstract

The electric properties of poly(ε-caprolactone) (PCL)/poly(vinyl butyral) (PVB) blends containing carbon black (CB) were studied as a functions of the PVB content and crystallization time. Comparison of the electric properties between the two cases (PCL/PVB blends and pure PCL) provided us useful information on the origin of the positive temperature coefficient (PTC) phenomenon of the resistivity. In this article, we report the influence of the morphology and the spherulitic structure on the distribution of CB, which results in the resistivity changes. Blending a small amount (up to 5%) of PVB caused significant changes in the electric property at a constant CB content. Both the resistivity and the intensity of PTC increased with the PVB content. These changes are ascribed to the change of CB distribution. A model is proposed to explain these results using Ohe's theory. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:409–416, 1997