Effects of Processing Sequence on Electrical Resistivity of Carbon Black Filled PP/PE Polymer Blends.

Abstract

Effects of processing order on the electrical resistivity of carbon black(CB) filled polypropylene/poly- ethylene(PP/PE) polymer blends have been investigated. The weight composition of PP/PE is set on around 40/60, at which the cocontinuity of the phases occurs. Two types of processing sequence have been examined ; (A) simultaneous mixing of PP, PE and CB, and (B) mixing PP with CB in advance, followed by mixing PE with the PP/CB mixture. The method (B) was proposed by Gubbels et al.[2] as the condition for the selective localization of CB at the interface of PS/PE blends. In this paper, it has been shown that the method (B) is useful to make the composite whose resistivity is less sensitive to CB content [3] and also to make the PTC (positive temperature coefficient) material. Compared with the method (A), the method (B) has exhibited ; (1) lower resistivit y at CB content from 10 to 12phr, (2) smaller variation of resistivity with the increase of CB content, (3) larger increase of resistivity with the increase of temperature (PTC intensity). These results suggest the formation of a conductive network at the interface between PP and PE by the method (B).