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

Abstract

Two types of room-temperature-vulcanized silicone rubber high-voltage outdoor insulator coatings were cured for different periods up to 600 hours at 25/spl deg/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/spl deg/C/min over the temperature range of 25 to 180/spl deg/C. It was found that the TSD current peak temperature, T/sub 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/sub m/S, from the beginning to the completion of the curing, were 25 and 35/spl deg/C, respectively, for the two types of samples. A logarithmic relationship between the T/sub m/ and the curing time, t/sub c/, was established on the basis of experimental data. An expression for the relaxation time in the terms of t/sub c/ was derived based on the TSDC theory.<>