Understanding electrical discharge endurance of epoxy micro- and nano-composites through thermal analysis

Thermal analysis of epoxy solid dielectrics containing micron sized, nanometer sized, and a mixture of the two sizes, of silica was performed. Measurements of thermal conductivity and thermo gravimetric analysis (TGA) were conducted. The TGA data showed higher weight loss initiation temperatures for samples containing up to 5% by weight of nanofillers as compared to the same material with much higher levels of conventional microfillers and unfilled sample, and this was in good correlation with the erosion damage due to corona. Average thermal conductivity measurements yielded results that was fairly well correlated with the rule of mixtures calculation, therefore could not explain the higher electrical discharge resistance or TGA data of nanofilled materials. Much research is needed to understand and exploit the advantages of nanocomposites and some ideas are presented.