Abstract: The heat accumulation caused by the high-power consumption of continuously upgrading electronic devices puts forward more requirements for efficient heat dissipation and fire safety of insulating materials. Herein, a bio-based flame retardant functionalized boron nitride nanosheet (BNNS@PP-Fe) was prepared via a simple mechanical exfoliation and self-assembly technology for reduction in the fire hazards of ethylene-vinyl acetate copolymer (EVA), as well as the improvement of its thermal conductive and mechanical performances. Arising from the highly flat oriented structure and rich flame-retardant functional groups of BNNS@PP-Fe, as well as the high compatibility between filler and matrix, the EVA/ATH/4BNNS@PP-Fe composites exhibited high thermal conductivity (0.78 W/(m K)) and outstanding flame retardancy with a dramatic decrease in peak heat release rate (p-HRR, 135.2 kW/m²) and total heat release rate (THR, 60.3 MJ/m²). Compared to neat EVA, the p-HRR and THR values of EVA/ATH/4BNNS@PP-Fe composite significantly decreased by 76.5 % and 47.3 %, respectively. Additionally, the flat-oriented structure and strong interfacial interaction also endow EVA/ATH/4BNNS@PP-Fe composites with excellent mechanical properties. This work provides a facile pathway to fabricate multifunctional BNNS and will promote the development of commercial insulating materials, not just EVA.

Key words: Boron nitride nanosheet, Thermal conductivity, Flame retardancy, Mechanical property, Ethylene-vinyl acetate copolymer