Authors: MUHAMMAD AKRAM, ATHAR JAVED, TASNEEM ZAHRA RIZVI
Abstract: Frequency and temperature dependence of dielectric constant \varepsilon' and dielectric loss \varepsilon" in pure polyester resin and polymer composites with various types of glass fiber are studied in the frequency range 330 Hz-3 MHz and in the temperature range 25-150 °C. The experimental results show that \varepsilon' and \varepsilon'' increased with the addition of glass fiber in polyester resin. The value of \varepsilon' decreased with increasing frequency, which indicates that the major contribution to the polarization comes from orientation polarization. Dielectric loss peaks were also observed in the composite materials at high temperature due to T_g of polyester. The value of \varepsilon' increased with increasing temperature, and is due to greater freedom of movement of the dipole molecular chains within the polyester at high temperature.
Keywords: Composite materials, orientation polarization, dielectric relaxation, polyester resin.
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