Development and electrical characterization of carbon soot filled polyester graded composites

In this paper a novel method to develop carbon soot filled polyester graded composites has been reported. Dielectric measurements were conducted on these graded composites in the temperature range from 30 to 150 degrees C and in the frequency range 1-10 kHz to study and analyse the effect of temperature and frequency variation on dielectric constant (epsilon') and dielectric dissipation factor (tan delta). It was observed that an increase of carbon soot content increased the dielectric constant gradually, which established the formation of a graded structure. Dielectric data were analysed using existing theoretical models. It was observed that Maxwell-Garnett model fits best for the dielectric data obtained experimentally for these graded composites. Compensation law confirmed the semi conducting behaviour of the composites. Cole-Cole plot for graded composites showed dielectric relaxation probably due to dipolar groups of polyester and interfacial polarization that occurred in the composites. (C) 2010 Elsevier Ltd. All rights reserved.