Electrical conductivity of epoxy resin filled with graphite nanoplatelets and boron nitride

The electrical conductivity of polymer composites with mixture of fillers, i.e. graphite nanoplatelets and hexagonal boron nitride (BN), was investigated. The content of graphite nanoplatelets (prepared by ultrasonication of thermoexfoliated graphite) in composite materials varied from 2 to 10 wt%. The DC conductivity was measured by the two- or four-probe methods in the temperature range of 77293 K. A model of the electrical conductivity of composite materials was proposed. It takes into account the conductivity of the graphite particles, the contact resistance between particles, and the number of electrically conducting chains from graphite particles. In the framework of this model the number of graphite chains and the contact resistance of investigated composite materials were calculated. It was shown that the addition of boron nitride increases the number of electrically conducting chains from the graphite particles, decreases the value of contact resistance Rk between graphite particles that leads to smaller changes of contact resistance with increasing temperature, and weakens the temperature dependence of electrical conductivity of composite materials.