Effects of polymer matrix and processing on the conductivity of polymer blends

The influence of different hosts, processing conditions and conducting fill ers on the percolation threshold (Phi (c)) of the resulting conducting blen ds was investigated. Results indicate that microscopic properties, such as the dipole moments of the side-groups, and distribution of these groups on the host polymer backbone govern the strength of host-filler interactions, and to a large extent, the value of Phi (c), rather than macroscopic proper ties such as surface tension, The grade of carbon black used in this experi ment was found to be polar in nature and it resulted in lower values of Phi (c) with the polar hosts, contrary to published Literature. In general, me lt blending has been shown to result in higher values of Phi (c) when compa red to hot pressing alone. In the latter method the conductive filler was f ound to be isolated at the grain boundaries of the polymer host, resulting in the formation of continuous conducting pathways at low filler concentrat ion. (C) 2001 Society of Chemical Industry.