Thermal conductivity and dielectric properties of EP composites filled by one-dimensional core-shell structured h-BN@SiO2 fibers

With the miniaturization and integration of modern high-power electronic devices, heat accumulation has become a key issue affecting their performance and reliability, which puts forward higher requirements for the thermal conductivity of polymer materials. In this study, boron nitride (h-BN) was dispersed into silica sol, and high aspect ratio core-shell fillers (h-BN@SiO2) were prepared by electrospinning. Then h-BN@SiO2/epoxy resin (EP) composites were prepared by hot pressing. Owing to the macroscopic and microscopic "double network" conduction paths constructed by h-BN@SiO2 fillers, the in-plane thermal conductivity (λ||) of h-BN@SiO2-Ⅲ/EP composites is 6.719 Wm−1K−1, which is 27 times that of EP, and the out-of-plane thermal conductivity (λ⊥) is 0.698 Wm−1K−1, which is 4 times that of EP. The simulation and the classical thermal conductivity model verify that the new designed filler in this paper has advantages over the traditional filler in terms of heat transfer. More importantly, the prepared composites also maintain excellent electrical insulation and dielectric properties, which provides a new idea for the preparation of high thermal conductivity electrical insulation composites.