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

The influence of different hosts, processing conditions and conducting fillers on the percolation threshold (Φc) of the resulting conducting blends 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 Φc, rather than macroscopic properties such as surface tension. The grade of carbon black used in this experiment was found to be polar in nature and it resulted in lower values of Φc with the polar hosts, contrary to published literature. In general, melt blending has been shown to result in higher values of Φc when compared to hot pressing alone. In the latter method the conductive filler was found to be isolated at the grain boundaries of the polymer host, resulting in the formation of continuous conducting pathways at low filler concentration. © 2001 Society of Chemical Industry