Conduction mechanisms in some graphite-polymer composites: The effect of a direct-current electric field

This paper deals with the possible conduction mechanisms in highly anisotropic composites comprising 0-10 vol% graphite Bakes within a polymer host. Conductivity measurements as a function of DC electric field have been made. In most cases, a non-linear behaviour of the current-voltage relationships is observed. A number of theoretical models are considered and we show that none of them is, by itself, able to explain our results. We further develop several arguments which lead us to consider the existence of a combined tunnelling effect and ionic conduction mechanism.