Fabrication of two multifunctional phosphorus–nitrogen flame retardants toward improving the fire safety of epoxy resin

Abstract To improve the fire safety of epoxy resin (EP), two novel phosphorus–nitrogen flame retardants, which named as diphenyl allylphosphoramidate (DPCA) and N-allyl-P, P-diphenylphosphinic amide (DCA), were synthesized by acyl chloride reaction introduced into EP for fabricating composites. The combustion tests showed that incorporation 5 wt% DPCA or DCA led to exceptional limited oxygen index (LOI) value (27.1% 31.6%). Besides, peak heat release rate EP-5 was reduced 40.69% 36.69%, respectively, compared pure EP. enhanced resistance ascribed trapping effect fillers in gas phase charring condensed phase. Furthermore, ultraviolet-visible spectra revealed both have considerable transparency. This study is expected broaden application industrial area.