Surface modification of aluminum hypophosphite and its application for polyurethane foam composites

Aluminum hypophosphite (AHP) is surface modified by melamine derivative to fabricate reactive solid flame retardant (MCAHP) for polyurethane foam. MCAHP is successfully prepared and characterized by FTIR and SEM. The flame-retarded efficiency of MCAHP in PU is higher than that of AHP. It demonstrated that MCAHP has better compatibility in PU matrix compared with AHP based on the SEM observation. After surface modification, due to the reaction between MCAHP and PU matrix, crosslinking might be formed between MCAHP and PU matrix, which contributes to the excellent compatibility of MCAHP in PU matrix, and as a result, the glass transition temperature of PU/MCAHP is 4 °C higher than that of PU/AHP. The thermal behavior of PU composites is characterized by TG and TG-FTIR, and results suggest the sublimation of melamine at about 320 °C because of the decomposition of the melamine derivative. The sublimation of melamine can consume abundant heat and dilute the oxygen concentration, which is benefit for the improvement of flame retardancy.