High-energy ball milling-induced facile preparation and controllable surface oxidation of black phosphorus for improving fire safety of epoxy resin via synergistic effect

Here we directly converted red phosphorus (RP) into black phosphorus (BP) through a facile and green one-step high-energy ball milling method. The surface oxidation degree of BP could be tuned by changing milling time and rotation speed. The partially oxidized BP was then utilized to improve fire safety of epoxy resin. Specifically, the peak heat release rate (PHRR) and the total heat release (THR) of epoxy composites were reduced by 36 % and 42 % with incorporating only 1.5 wt% BP, respectively. Comparatively, adding the same amount of conventional RP failed to achieve a reduction in smoke production, while the total smoke production (TSP) of epoxy composites with BP decreased by 20 %, suggesting a promising smoke suppression ability of milled BP. The morphology and composition results of char residue demonstrated that the elemental phosphorus and its oxidized products possessed a significant synergistic catalytic effect on promoting char formation in the condensed phase.