UV WEATHERING OF EPOXY AND SILICONE RUBBER COMPOSITES FOR HIGH VOLTAGE ELECTRICAL INSULATION UNDER AC STRESS

Abstract

In this research an attempt was made to elucidate whether the addition of micro and/or nano silica and alumina trihydrate particles can improve the resistance of silicone rubber and epoxy material against synergistic effects of temperature UV, and high voltage stress. Six types of composites were manufactured (SRNC/2.5, SRNC/5, SRMNC, NE, EMC, and ENC) and were subjected to multi stress aging in a test chamber. The duration of the multi stress aging was 2500 hours. The analyses techniques used were visual observation, hydrophobicity classification, measurement of leakage current, insulation resistance and Scanning Electron Microscopy. Results show that epoxy composites showed discoloration whereas only minute discoloration was found in SRNC/5. The resistance to hydrophobicity reduction offered by SRNC/5 and SRMNC was excellent as compared to SRNC/2.5 whereas all the samples of epoxy offered significant hydrophobicity loss. Filler exposure and extreme erosion took place in EMC and ENC as compared to NE whereas silicone rubber composites showed no such behavior. The results of UV weathering of SR and Epoxy composites indicate that Epoxy composites were complete failure but the addition of nano and micro/nano fillers in Silicone Rubber can improve its UV weathering resistance considerably by creating an effective UV shielding layer.