Flame retardant polypropylene filled with the intumescent flame retardant containing the elements of phosphorus, nitrogen and silicon

Phosphorus oxychloride, pentaerythritol, p-phenylenediamine and amino-terminatedsilicone oil were used to synthesize intumescent flame retardant containing the elements of phosphorus, nitrogen and silicon (P-N-Si-IFR). The inflaming retarding effect of the normal intumescent flame retardant containing the elements of phosphorus and nitrogen (P-N-IFR) and P-N-Si-IFR on PP were studied through limiting oxygen index, cone calorimetry tests and thermogravometric analysis. Limiting oxygen index, average heat release rate and mass residue of PP/P-N-IFR (70/30, mass ratio) are 30.7, 240 kW/m2 and 8.7% respectively, and those of PP/P-N-Si-IFR (70/30, mass ratio) are 34.0, 94 kW/m2 and 15.2% respectively, which indicate the inflaming retarding effect and thermal stability of P-N-Si-IFR on PP are better than those of P-N-IFR on PP. The char layerstructure was investigated by X-ray diffraction and the flame-retardant mechanism of P-N-Si-IFR on PP was explored.