Degradation of Silicone Rubber under AC or DC Voltages in Radiation Environment

The aging of silicone rubber by gamma irradiation has been investigated. Silicone Rubber flat specimens were aged by gamma irradiation with three different doses and the resistance to tracking on applying ac and de voltages was examined. The results show that the resistance to tracking under dc voltages is less than that of their ac values. This necessitates a separate standard for determination of tracking resistance under dc voltage. Laboratory examination of material changes together with visual observations and leakage current measurements were also made. The dc stressed samples showed a higher surface degradation compared to those stressed by ac voltages. The erosion depth and contact angle affected by radiation have been studied. The aging of the surface was assessed by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy with Energy Dispersive X-ray Analysis.