Space charge performance of epoxy composites with improved thermal property at high temperature under high electric field

Abstract This article investigates the high‐temperature space charge dynamics of epoxy composites consisting of micro and nano‐AlN fillers under a high electric field. The test temperatures are selected for the space charge measurement based on the glass transition temperature. An indigenously designed pulse electro‐acoustic system measures the space charge distribution up to 150°C. The stepwise‐increasing field is applied to the test samples from 20 to 100 kV/mm at the rate of 20 kV/mm. The epoxy hybrid composites show negligible space charge accumulation at room temperature and low electric fields, which increases at high temperatures and high electric fields. The hybrid composite with 1 wt% nanoparticle has a dielectric breakdown at 100 and 150°C under 100 kV/mm with an evident amount of accumulated charges. In the hybrid composites with 3 and 5 wt% nanofillers, the breakdown is observed under 80 and 100 kV/mm, respectively, at 150°C. Notably, the micro‐nano filler addition significantly improves the thermal conductivity of the epoxy resin. The uniform dispersion of the fillers affects the electrical and thermal properties of the epoxy. The charge dynamics‐related mechanism is proposed on the basis of morphological characterization and thermal properties of epoxy and its composites.