Simultaneously Enhanced\nThermal Conductivity and Dielectric\nBreakdown Strength in Micro/Nano-BN/Epoxy/PC Multilayer Composites

Because of their significant application potential in\nboth power\nelectronic devices and power equipment, the development of polymer-based\ncomposites with high thermal conductivity and breakdown strength has\ngained increasing attention. In this study, multilayer structural\ncomposites were successfully prepared. Micro/Nano-BN was prepared\nby electrospinning technology, showing positive gradient (PGD) and\ninverse gradient (IGD) distribution in an epoxy and polycarbonate\n(PC) blended matrix. The gradient distribution of nanofillers fully\nfilled in each layer greatly enhances the breakdown strength of the\ncomposite dielectric. In comparison to traditional composites, the\nbottleneck of increasing thermal conductivity and breakdown strength\nat the same time was successfully overcome. The breakdown strength\nof the 2–6–2 structure multilayer positive gradient\ncomposite dielectric reaches 107.1 kV/mm, 76.7% higher than the single-layer\nuniform composite dielectric and thermal conductivity of 0.38 W/(m·K)\n(2.11 times that of epoxy). The 6–2–6 structure obtains\nthe highest breakdown strength of 110 kV/mm and a thermal conductivity\nof 0.33 W/(m·K). The thermal conductivity of the multilayer composite\ndielectric of both gradient structures changed; this phenomenon provides\nan idea for polymers to improve thermal conductivity.