Comparative Research on Aging Properties of HTV Silicone Rubber via Outdoor Electric Aging and Ultraviolet Accelerated Aging

In order to further study the aging properties of high temperature vulcanization (HTV) silicone rubber for composite insulator in the high-altitude region, tests of outdoor electric aging and ultraviolet accelerated aging have been carried out in the paper. The contact angles test, scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR) were used to study the microscopic physical properties of samples after the aging tests. SEM observed that the surface flatness of samples declined, holes and particles increased on the sample surface, a large number of fillers exposed. The results of FTIR showed that Si-C bonds in the side chain in Si-O backbones were broken by ultraviolet radiation and methyl groups were oxidized, a small amount of fire retardant (Al2O3•3H2O) were decomposed, hydrophilic groups increased, all which have happened on the HTV silicone rubber after both the aging tests under the same ultraviolet radiation. The differences between the aging properties of two kinds of tests are that the aging extent of samples after outdoor electric aging was severer than that in ultraviolet accelerated aging, and the surface hydrophobicity of it after outdoor electric aging increased compared to ultraviolet accelerated aging. The aging of HTV silicone rubber for composite insulator is mainly caused by strong ultraviolet radiation in high-altitude region.