Phosphorus/nitrogen compound and zinc hydroxystannate-modified graphene oxide for efficient flame retardancy and smoke suppression of epoxy resin

Despite many important industrial applications, epoxy resin (EP) suffers from high flammability and toxicity emission. To circumvent the problem, phosphorus/nitrogen compound and zinc hydroxystannate-modified graphene oxide is successfully fabricated. The functionalized graphene (FGO) exhibits high thermal stability and excellent dispersity in the EP matrix. The storage modulus of EP/FGO2 increases to 2713 MPa from 2176 MPa. Meanwhile, the results show a significant reduction in fire, smoke, and toxicity hazards. Compared with pure EP, incorporating only 2.0 wt% FGO2 into EP, smoke production rate, the peak heat release rate, and peak carbon monoxide production are dramatically reduced by 40.1%, 40.3%, and 37.7%, respectively. Especially, the fire growth index of EP/FGO2 is reduced by 36.0%. Moreover, the limiting oxygen index value of EP/FGO2 enhances to 28.5% and its UL-94 achieves V-1 rating. These superior fire safety properties are due to the catalytic, barrier effect of the FGO, the compact char blocks the diffusion of smoke and heat during combustion. This work provides an efficient strategy to prepare a promising graphene-based flame retardant to improve the fire safety and mechanical property of EP.