Electrical properties of conductive network in carbon fibers/polymer composites

The electrical properties of PAN-based carbon fibers/polycarbonate composites were studied using the AC impedance technique. Impedance, dielectric constant, dielectric loss, relaxation time, and AC-conductivity showed frequency, temperature, and carbon fiber-concentrations dependence. It was found that the dielectric constant and dielectric loss of the prepared composites increase with the increase in the carbon fiber concentration and decreasing frequency. The thermoelectrical behavior was studied as a function of temperature for the composite of 18 wt% fibers concentration. It was found that the dielectric constant and AC-conductivity increase with temperature, while the activation energy decreases. The observed AC electrical results are explained as a function of fiber concentration and temperature, based on the hopping of conducting impurities and complexes into localized energy states.