Preparation of ionic liquid multifunctional graphene oxide and its effect on decrease fire hazards of flexible polyurethane foam

An ionic liquid (IL) functionalized graphene oxide (ILGO) containing phosphorus was prepared by GO and ionic liquid ([BMIM]PF6), whose structure was characterized via XRD, FTIR, TG and EDS. Then combined with flame retardants (ammonium polyphosphate-APP and expandable graphite-EG), ILGO acting as synergistic agent was introduced into flexible polyurethane foam (FPUF) to modify its flame retardancy, which was assessed by UL-94, TG, limiting oxygen index (LOI) test and cone calorimeter test (CCT). The results show that the FPUF composites with 0.05 phr ILGO, 7.5phr EG and 7.5phr APP got a LOI of 29.0% and passed the V-0 rating for UL-94, while that for FPUF/EG/APP composites is only 26.7 and not classified at the same loading. The results of CCT showed that ILGO could reduce heat release, smoke suppression and toxic gas production of the FPUF composites. For the FPUF/EG/APP/ILGO composites, the PHRR, THR and TSP were decreased by 24.6%, 32.6% and 18.5%, respectively, compared with the FPUF/EG/APP/GO composites. TG and morphology of char residue reveals that the IL expedite the formation of dense and continuous charring layer and physical isolating effect of GO, which is the inherent reason for the good flame retardancy.