FREQUENCY-DEPENDENCE OF THE COMPLEX DIELECTRIC-CONSTANT OF POLY(ETHYLENE OXIDE) UNDER HYDROSTATIC-PRESSURE

Electrical-impedance measurements have been made in the frequency range 5 Hz to 10 MHz in pure poly(ethylene oxide) having a molecular weight of 600 000 from 254 K nearly up to the melting point of the crystalline phase (about 330 K). As the temperature approaches the melting point there are large increases in the real epsilon' and imaginary epsilon'' parts of the dielectric constant. The frequency dependence of epsilon' is characterized by a primary-relaxation process, whose frequency increases with increasing temperature as a consequence of decrease of the average structural relaxation time. There is strong evidence that this low-frequency dispersion rises mainly from the diffusive transport of localised charge carriers rather than a purely orientation relaxation process. In addition the effects of hydrostatic pressure (0-0.25 Cpa) on the frequency dependences of the real epsilon') and imaginary epsilon'' parts of the dielectric constant have been measured in the same temperature range.