Novel multifunctional melamine borate - boron nitride nanosheets/epoxy composites with enhanced thermal conductivity, flame retardancy and satisfying electrical insulation

In this work, we present a solution to use nitrogen and boron co-effect flame-retardant (melamine borate, abbreviated as MB) functionalized boron nitride nanosheets (MB-BNNS) to improve the thermal conductivity and flame retardance of epoxy resin and maintain excellent electrically insulating properties simultaneously. In brief, the MB-BNNS were prepared by grafting MB onto boron nitride surfaces via a simple ball-milling and eco-friendly water scrubbing process. Subsequently, the epoxy composites with uniformly dispersed MB-BNNS were obtained by wet processing. The obtained epoxy composite with 5 vol% EP/MB-BNNS showed a optimally comprehensive performance. Compared to pure epoxy, it showed 108% of increase in thermal conductivity (TC), 36.44% and 32.06% of decrease in peak heat release rate (PHRR) and total heat release rate (THR), and slightly decrease in dielectric breakdown strength. More remarkably, the release percentages of toxic and combustible gases in EP/MB-BNNS composite system were significantly reduced, which were measured by a in-situ measurement.