Dielectric properties of poly(phenylene sulfide) as a function of temperature and frequency

Dielectric properties of poly(phenylene sulfide) (PPS), a kind of super engineering plastic, were investigated over a wide temperature range by measuring its frequency spectra of complex permittivity and thermally stimulated polarization and depolarization currents (TSPC and TSDC). Experimental results indicate that its permittivity and dielectric loss factor remain stable and maintain low values up to around 140 °C, despite the fact that its glass transition appears at a much lower temperature of 88 °C. As for TSPC and TSDC, a very small peak associated with the glass transition appears at about 110 °C. Furthermore, a much clearer TSPC peak due to orientation of dipole moments associated with the ether linkage induced by the cross-linking reaction appears at about 150-170 °C. The corresponding TSDC peak due to randomization of these dipoles is very small compared to the TSPC peak, since PPS was cross-linked during the high-temperature process in the TSPC measurement, which made rotation of the dipoles difficult. At temperatures higher than 150 °C, both the real and imaginary parts of the complex permittivity show significant increases with increase in temperature and decrease in frequency. This is attributable to the transport of the charge carriers.