Terminal Chlorine Affected the Short-Term Electrical Properties of Epoxy Resin Materials

Epoxy resin insulating materials are prone to charge accumulation under the high voltage and high temperature stress, which can distort the electric field distribution and eventually lead to insulation failure. Appropriately increasing the electrical conductivity of epoxy resin materials could effectively accelerate the dissipation of accumulated charges and may thus provide a potential method to improve the insulation strength. The conductivity of epoxy resin materials is closely related to their cross-linked molecular structure. In this work, based on the structural changes of cross-linked molecules, we explore the mechanisms by which terminal chlorine affects the energy level distribution and trap properties of cross-linked molecules. These influence mechanisms could be explained in terms of electron cloud offset and electron energies. According to quantum chemical calculation results, the changes in the charge transport process in cross-linked molecules are compared, and the volume resistivity and dc breakdown strength data of the epoxy resin materials are analyzed at different terminal chlorine contents. The results suggest that terminal chlorine alters the charge hopping barrier in the cross-linked molecules, potentially affecting the intramolecular charge transport process.