The Effects of Heat Treatment on Dissipation Factors of Silicone Rubber

Silicone rubber specimens have been prepared by the reaction of a, w-dihydroxypoly(dimethylsiloxane) with tetraethoxysilane using dibutyltin dilaurate as a catalyst at a relative humidity of 100% at 25°C. The vulcanized rubber specimens were subsequently heattreated at 200°C in N2 and O2 atmospheres and their dissipation factors measured at 50 Hz between 20 to 200°C in air. It was found that the dissipation factor values were a function of the heat treatment. The infrared spectra of dibutyltin dilaurate were obtained as it was believed that the dibutyltin dilaurates would be partly hydrolyzed to lauric acid and dibutyltin dihydroxide at a relative humidity of 100% at 25°C and that the dibutyltin dilaurate and dibutyltin dihydroxide would be partly oxidized to tin(IV) dioxide at 2000C in O2 The effect of heat treatments under various atmospheres was investigated on the rubber specimens to which lauric acids and dibutyltin dihydroxides had been added. It was concluded from the experiments that variations in the dissipation factor values, caused by changes in the heating atmospheres, were due to the evaporation of the lauric acid and the oxidation of dibutyltin dihydroxide.