An examination of the environments for aging of polymers

Initial tracking wheel tests with alumina filled silicone rubber insulators show that the type of solution used influences the leakage current and material properties. The mixed salts solution causes little change in leakage current over the 500 hour test, but produces a significant change in the loss tangent of the sample. Synthetic rain testing showed a slower initial rate of change in leakage current compared with sodium chloride tests, but as testing progressed, the leakage current continued to increase while the sodium chloride leakage current did not increase significantly beyond the initial values over the same period. Upon examination of the dielectric properties, it was found that synthetic rain caused a significant change in the loss tangent. The degree of loss tangent degradation was influenced by the alumina filler level, with higher level samples exhibiting a greater loss tangent degradation