Analysis of the ac Current Properties of a PAN-Based Carbon-Fiber/ Polycarbonate Composite

Abstract

Some electrical properties of a polycarbonate/PAN-based carbon-fiber composite are reported. Impedance measurements performed at the frequency range of 1Hz-100 kHz on various composite specimens showed frequency, filler concentration, and temperature dependence. The observed results are similar to those reported on most dielectric solid materials. The complex dielectric constant determined from the impedance data analysis yields the dielectric constant, which shows strong dependence on the fiber concentration. The real part varies by 1/f at frequencies below 300 Hz, indicating that the mterfacial polarization dominates and enhances the dielectnc constant at low frequencies. The loss factor shows some oscillatory behavior, which indicates that different relaxation processes operate in the composite bulk. The loss factor increases with increasing filler concentration as a result of enhancement of the electrical conductivity. The observed decrease in the impedance with temperature may be attributed to tunnelling and polariza tion current effects.