Synthesis of an environmentally friendly P–N synergistic flame retardant and its effect on the properties of epoxy resin

Additive flame retardants are increasingly frequently used in the current research on flame retardant techniques for polymer materials. In this work, 2-aminopyrazine and spiro-phosphorus oxychloride (SPDPC) were combined to create an environmentally friendly flame-retardant aminopyrazine spiro pentanol bisphosphonate (APPC). This solution addressed the issues of conventional flame retardant dispersion and low flame-retardant efficiency. The LOI value can reach 29.7 % with the addition of 7 wt% APPC, and the UL-94 test was able to achieve the V-0 rating. Furthermore, a remarkable decrease of 62.23 % in the peak heat release rate (pHRR), 51.23 % in the peak value of the CO production rate, and 63.57 % in the peak value of the CO₂ production rate was shown by the cone calorimeter experiment. The heat insulation and smoke suppression effect is also exceptional. According to the analysis of TG-FTIR, IR, XPS and SEM results, there is sufficient evidence that APPC as a phosphorus-nitrogen intumescent flame retardant (IFR), can produce beneficial effects in both catalyzing char formation and inhibiting toxic smoke production.