A Cu-MOF-decorated ammonium polyphosphate for epoxy resins with reduced smoke release and enhanced char layer

Inspired by the significant catalytic charring effect of metal–organic frameworks (MOFs), Cu-MOF decorated ammonium polyphosphate (APP@Cu-MOF) was prepared by coupling agents to improve the fire safety of epoxy resin (EP). After adding 9 wt% APP@Cu-MOF, the fire performance of EP is significantly improved with limiting oxide index (LOI) value of 29.4 and UL-94 V-0 rating. The peak heat release rate (PHRR), total smoke production (TSP), CO production, and CO 2 production of EP composite samples decreased by 34.6%, 54.7%, 24.6% and 30.0%, respectively. It is proposed that the synergistic effect among Cu-MOF and APP promoted the char formation of EP. The dense carbon layers formed a barrier that prevented the transfer of heat and inhibited the release of toxic gases, thus acting as a flame retardant. This work provides a new strategy to develop a high-efficient MOF-decorated flame retardant with smoke inhibition, toxicity reduction, and catalytic carbonization effect.