Space charge accumulation in epoxy resin and its nanocomposites under temperature gradient

Space charge accumulation in the dielectrics can greatly distort the electric field, and then greatly influence the in-situ property, degradation and breakdown properties. It is affected by several factors like electrical field, temperature and fillers. The focus of this paper is the behavior of space charge in the unfilled/filled epoxy resin under temperature gradient. In this work, neat epoxy resin and SiO₂-epoxy resin nanocomposites were prepared, and the measurements were carried out under different electrical field (5-50kV/mm) and different temperature gradient (ΔT=0-60°C) by a modified pulsed electro-acoustic system. At room temperature (T=20°C, ΔT=0°C), only homocharge accumulation near the anode is observed in neat epoxy resin, while no charge accumulation is detected in the bulk of nanocomposites. When the temperature gradient is high enough (ΔT≥40°C), a lot of charge is injected from the high temperature electrode (cathode) and accumulates in the bulk of samples. Most of charge accumulates near the cathode in epoxy resin, while the charge accumulated in nanocomposites extends through the thickness of the sample. The reason for the different behavior of space charge in neat epoxy resin and nanocomposites is discussed.