Effects of tropical climate on the performance of RTV silicone rubber with various filler contents

Room temperature vulcanization (RTV) silicone rubber is one of the new materials for outdoor insulators especially for high-contaminated areas. Before applying the material in a tropical region like Indonesia it is important to investigate the effects of the tropical climate on the properties of the materials. We have investigated the aging of RTV silicone rubber with various filler contents in Bandung for 120 weeks. There were two groups of samples. The first group was directly exposed to weather while the other one was laid under a shielding which prevented direct exposure of UV radiation, pollution and rain. During the aging we measured the hydrophobicity (contact angle), permittivity, tan δ, and loss of weight. The investigation results indicated that samples exposed to outside climate directly showed better hydrophobicity, but greater changes of permittivity, tan δ and weight were observed. Water absorption played an important role in the change of permittivity and tan δ. The removal of water by drying was able to restore the permittivity and tan δ almost to the original values. RTV with higher filler content showed higher ability to resist the surface degradation. Analysis of the residual weight may be used to calculate expected lifetime of the material in service under tropical condition