Thermal and Electrical Properties of Epoxy Composites Filled with 3D h‐BN/TOCNF Fillers

Abstract Epoxy resin (EP) has been widely used in electronic packaging and electrical equipment due to its excellent electrical insulating properties. However, the low thermal conductivity (TC) of EP limits its wider application and needs to be further improved. In this study, 3D hexagonal boron nitride (3D h‐BN) is successfully synthesized by utilizing TEMPO oxidated cellulose nanofiber hydrogels (TOCNF) as an interlocking skeleton, and then 3D h‐BN/TOCNF are chosen as the functional fillers to improve the TC of EP. The microstructure, TC, and electrical insulating properties of epoxy composites are systematically characterized and analyzed. The results show that epoxy composites filled with 3D h‐BN/TOCNF deliver a significantly improved TC and maintain excellent insulating properties. When the filled content of 3D h‐BN/TOCNF is 9 wt.%/21wt.%, a TC of 0.86 W (m K) −1 is obtained at 25 °C, which also demonstrates favorable electrical insulating properties with a volume resistivity of more than 10 15 Ω m and breakdown strength of 186.1 kV mm −1 . This work offers an efficient method to improve the thermal and electrical performances of EP for electronics and electrical engineering applications.