Influence of temperature on mechanical and insulation properties of epoxy-layered silicate nanocomposite

The aim of this study is to investigate the influence of temperature on the mechanical and insulation properties of a newly developed epoxy-layered silicate nanocomposite. This nanocomposite has a higher thermal resistance with respect to mechanical properties than a base epoxy resin (epoxy resin without fillers). The volume resistivity of the nanocomposite gradually decreases with increasing temperature, and its relative permittivity gradually increases with increasing temperature. Its properties are more dependent on temperature than those of the base epoxy resin. Moreover, under a constant ac voltage, the insulation breakdown time of the nanocomposite was twice as long as that of the base epoxy resin at 20 degrees C and six times as long at 80 degrees C. In particular, at 145 degrees C, the nanocomposite had a breakdown time of more than 20,000 minutes while the base epoxy resin had breakdown time of 280 minutes. This improvement in breakdown time resulted from electrical treeing shapes with many branches and smaller internal stress of the nanocomposite in comparison with the base epoxy resin.