Chemically inorganic modified ammonium polyphosphate as eco-friendly flame retardant and its high fire safety for epoxy resin

The flame retardant of epoxy resin (EP) with simultaneously eco-friendly environment and high efficiency had gained much attention. Here, a tactful route was utilized to chemically modify ammonium polyphosphate ([email protected]) through ion exchange reaction between APP and Iron (III) nitrate hexahydrate. Adequate characterizations confirmed the successful preparation of [email protected], then the cone calorimeter results displayed that the heat and smoke release of 5 wt% [email protected]/EP composite had been largely decreased. In addition, the flame-retardant mechanism investigation illustrated that iron (III) not only obviously efficiently catalyzed the charring process of EP, but also promoted the early formation of P–O–C group in [email protected]/EP composite via catalysis during combustion, which could reinforce the intumescent char structure and fire safety for EP.