Construction of MXene-based flame retardant with multiple carbonization towards for reducing fire hazard and smoke release of epoxy resin

MXene is a promising flame retardant for composites. Currently, how to construct modified MXene nanomaterials with high flame-retardant efficiency is a challenge. In this work, a functionalized MXene-based flame retardant (MXene-AP-Cu) was synthesized by grafting phytic acid copper complex onto the surface of MXene, and was utilized to prepare high performance epoxy resin (EP) composites. Only 2 wt% MXene-AP-Cu increased limited oxygen index (LOI) of EP to 29.7% from 21%, with an enhancement of 41.4%. In addition, EP/2% MXene-AP-Cu presented excellent suppression effect on the release of heat, smoke and CO, as reflected by a 40%, 18%, 25.3% and 33.3% decreases in peak of heat release rate (PHRR), total heat release (THR), total smoke product (TSP) and peak of CO release rate, respectively, compared to EP. The multiple carbonization of MXene-AP-Cu, including lamellar barrier effect, catalytic carbonization of MXene and copper irons, dehydration and carbonization of phytic acid, contributed to better flame retardancy. Besides, the impact strength of EP/MXene-AP-Cu was increased to a certain extent, compared to EP.