Electric-field-assisted thermal and electrical properties of liquid crystal epoxy resin-filled epoxy composites

Abstract Traditional bisphenol a epoxy resins possess excellent molding and mechanical properties, but their inherently low thermal conductivity and limited insulation properties make it difficult to simultaneously meet the requirements of heat dissipation and electrical insulation in high-power-density electrical equipment. Liquid crystal epoxy resin (LCER) can be incorporated into epoxy matrices as a functional phase in epoxy-based composites. Electric-field-assisted fabrication offers an effective means to regulate the microstructure of polymer composites and improve the thermal and electrical properties. Nevertheless, for LCER-filled epoxy systems, previous studies focused on the thermal transport characteristics, while the electrical insulation performance under assisted electric field has rarely been reported. In this study, LCER/epoxy composites were fabricated under assisted electric fields ranging from 0 to 1 kV mm −1 , and their thermal conductivity and electrical insulation properties were comprehensively evaluated. The application of an assisted electric field induces the alignment of LCER chain-like structures and leads to a non-uniform distribution along the field direction, which is accompanied by concurrent enhancements in heat conduction and insulating performance. For the 1 kV mm-assisted composite, the thermal conductivity increased by 19.4% compared with the untreated composite. The volume resistivity increases by about four times, and the activation energy associated with volume resistivity increases by approximately 20%. In addition, the DC breakdown strength increases by about 11.3%, and the average volume charge density decreases by about 9.4%. This work provides a reference for the research on the application of epoxy resin in achieving high thermal conductivity and electrical insulation properties.