Influences of transformer oil on performance of RTV silicone rubber

The performance of room temperature vulcanized (RTV) silicone rubber under various operation conditions is always a hot point in the study of external insulation. The influences of transformer oil on performance of RTV silicone rubber have been little investigated, which are crucial issues for the RTV silicone rubber covering transformer bushing because of the potential transformer oil leakage problems. In the present work, transformer oil immersion experiment is applied to explore the influences of transformer oil on the performance of RTV silicone rubber. Samples are immersed into transformer at 70 °C and 110 °C for 4, 8, 24, 72, 168 and 336hrs, respectively. They are analyzed by contact angle measurement and Fourier transform infrared spectroscopy (FTIR), and the transformer oil is studied using gas chromatography (GC). The results show that, contact angle increases when the immersing time is short and fluctuate with the immersing time increasing, and they show a good hydrophobicity for all of the samples. FTIR analysis indicates the absorptions due to O-H bonds, C-H in CH
₃
, Si-CH
₃
, Si-O-Si, and Si(CH
₃
)
₂
decrease for the immersed ones, and temperature has an impact on the decrease, especially for the O-H bonds. GC analysis, which is used to verify the proposed hypothesis that low molecule weight is supposed to be suck into transformer oil during immersion, gives a result to be further validated due to the complexity of transformer oil composition. One can conclude that transformer oil have great impacts on the performance of RTV silicone rubber, but it cannot be examined simply by contact angle measurement. FTIR analysis is an effective method to investigate it. An indirect method by using GC is potential and further analysis is required in further study.