Dielectric relaxation at ultra low frequency

The isothermal charging and discharging currents were recorded for polyamide 11, polyethylene terephthalate and low density polyethylene in a large range of temperatures below and above the glass-rubber transition temperature of the amorphous phase, for different electrical fields and different charging and discharging times. The results showed that the low frequency relaxation process is complex and different contributions having the loss peak in the range 0.01 MHz to 0.1 Hz were revealed. The data are in good agreement with those obtained from dielectric relaxation spectroscopy and from thermally stimulated discharge current measurements.