Application of TSDC technique in study of relaxation during curing process of RTV silicone rubbers

Two types of room-temperature-vulcanized silicone rubber high-voltage outdoor insulator coatings were cured for different periods up to 600 hours at 25°C and 80% relative humidity. The thermally stimulated discharging current (TSDC) of samples with different curing degrees, ie., being cured for different periods, was measured at a heating rate of 7°C/min over the temperature range of 25 to 180°C. It was found that the TSD current peak temperature, T_m , increased with increase of curing period, and saturated finally at a stabilized value when the curing process was completed. The net increases of T_mS, from the beginning to the completion of the curing, were 25 and 35°C, respectively, for the two types of samples. A logarithmic relationship between the T_m and the curing time, t_c, was established on the basis of experimental data. An expression for the relaxation time in the terms of t_c was derived based on the TSDC theory