Synergistic effects between [Emim]PF6 and aluminum hypophosphite on flame retardant thermoplastic polyurethane

Abstract

This article mainly studies the synergistic flame retardant effects and smoke suppression properties of ionic liquid ([Emim]PF₆) and aluminum hypophosphite (AHP) on thermoplastic polyurethane (TPU); AHP was used as the main flame retardant and [Emim]PF₆ was used as the catalytic/synergistic agent. Then, the flame retardant effects of all TPU composites were tested using the limiting oxygen index (LOI), UL 94 test, cone calorimeter test (CCT), smoke density test (SDT), thermogravimetric analysis (TG) and thermogravimetric/Fourier transform infrared spectroscopy (TG-IR). Remarkably, with 0.0625 wt% content of [Emim]PF₆ and 19.9375 wt% content of AHP, the sample reached a UL 94 V-0 rating, the LOI value increased by 35.75%, and the heat release and smoke production reached the minimum value among all samples. TG and TG-IR data reveal that AHP and [Emim]PF₆ improve the thermal stability of samples at high temperature and reduce the production of some toxic gases.