Electrical properties of polymer composite based on polyester and chopped strand mat fiber E-glass

Frequency and temperature dependence of dielectric constant (ε ) and dielectric loss ( ε ) ,ac conductivity, , dissipation factor(tan, imaginary part of electric modulus(M ) and activation energy were determined in pure polyester resin and polyester composite with various volume fractions of chopped strand mat glass fiber (3.5%, 7%, and 10%) prepared by hand lay-up technique, in the frequency range 100 Hz-1 MHz and in the temperature range 25-100 ºC. The experimental results show that and dielectric constant, dielectric loss, and the dissipation factor increased with the addition of chopped strand mat glass fiber in polyester resin. The dielectric constant increases considerably with the addition of glass fiber in polyester resin, . The value of dielectric constant, dielectric loss and dissipation factor decreased with increasing frequency. this decrease more evident with increasing the volume fractions of C.S.M. fiber E-glass and tend to saturate at higher frequencies. The values of dielectric constant and dielectric loss, and dissipation factor increased with increasing temperature. Dielectric loss decreases with applied frequency until it stabilizes at about 1 MHz, also, dielectric loss peaks were observed in the polyester composite at high temperature are due to Tg of polyester. The exponential factor (s) found to be in the range 0.725≤s≤0.998,that frequency dependence of conductivity satisfied the Ws law , the increase in ac conductivity with increasing temperature and frequency of the applied field, was reported to be due to correlated barrier hopping (CBH), also it is found that the activation energy decreases with increasing fiber volume fraction.