Nickel Ammonium Phosphate Nanowires Modified g-C3N4 for Improving the Fire Safety of Epoxy Resin

In this study, we designed a new flame retardant to improve the fire safety performance of epoxy resin (EP). Graphitic carbon nitride (g-C 3 N 4 ) was derived from melamine through a solid-phase reaction, after which nickel ammonium phosphate nanowires (NiNH 4 PO 4 ·H 2 O) were grown on the g-C 3 N 4 using a hydrothermal method. The resulting material (g-C 3 N 4 /NiNH 4 PO 4 ·H 2 O) was a halogen-free flame retardant containing effective flame-retardant elements such as C, N, P, and Ni. Subsequently, g-C 3 N 4 /NiNH 4 PO 4 ·H 2 O was added to EP to test its fire resistance and mechanical properties. When the amount of g-C 3 N 4 /NiNH 4 PO4·H 2 O was 5 phr (per hundred resin), the peak of smoke production rate and peak heat release rate of the EP composite were reduced by 35.42 and 70.4 %, respectively, compared to those of pure EP. Meanwhile, the limiting oxygen index of the EP composite was enhanced to 30.0 % from 24.5 % (pure EP). Finally, the flame-retardant mechanisms of the gas phase and condensed phase were explored.