The preparation of ionic liquid doped graphene composite and its synergistic flame retardant effect with hexaphenoxy cyclotriphosphazene on epoxy resin

Abstract

<p indent=0mm>In this article, ionic liquid doped graphene (GnP@ILs) was successfully synthesized by green and environmentally friendly wet ball milling from expandable graphite and 1-butyl-3-methylimidazole hexafluorophosphate ionic liquid ([BMIM]PF₆), and its surface morphology, crystal structure and chemical structure were characterized. GnP@ILs alone or mixed with hexaphenoxy cyclotriphosphazene (HPCTP) was added to epoxy resin (EP) to study its effect on the comprehensive properties of EP composites. Limiting oxygen index (LOI), vertical combustion (UL-94) and cone calorimetry test results show that GnP@ILs can improve the fire resistance of EP composites, and the EP composites (EP/7.2wt%HPCTP/1.8wt%GnP@ILs) has the best flame retardant performance, with an LOI of 33.8%, and has passed the UL<sc>-94 V</sc> 0 rate. The peak heat release rate and total heat release rate of EP/7.2wt%HPCTP/1.8wt%GnP@ILs were decreased by 55.54% and 44.28%, respectively. At the same time, the addition of [BMIM]PF₆ enhanced the interface compatibility between the flame retardant and EP, and the tensile strength and impact strength of EP composites were significantly improved.