One-pot synthesis of aluminum hypophosphite encapsulation in expanded halloysite lumen for reducing fire hazard and environmental pollution

Halloysite nanotubes (HNTs) have been studied and applied in the field of flame retardant. It is still a challenge to realize a facial method to accommodate more flame retardants while expanding the inner lumen of HNTs simultaneously. In this work, the inner cavity expansion and the encapsulation of aluminum hypophosphite of HNTs is obtained (AHP@HNTs) by a simple one-pot synthesis. The prepared AHP@HNTs were applied to the flame retarded Epoxy resin (EP) and the results show that AHP@HNTs can achieve better flame retardant effect at a lower addition (3 %) than individual additions of AHP or HNTs at higher addition (5 %) manifested by the reduction of the heat and smoke release. The decrease of effective heat combustion (EHC) reveals a gaseous phase flame retardant mechanism. Moreover, the environmental pollution after combustion was evaluated by an innovative method based on the particulate collection from smoke. The reduction of particulate formation and the improvement of char residue confirms the condensed flame retardant mechanism of AHP@HNTs on EP.