Thermal degradation mechanism of montmorillonite synergistic intumescent flame retardant polypropylenes

The combination between montmorillonite (MMT) and ammonium polyphosphate (APP)/dipentaerythritol (DPER) used in intumescent flame retardant PP leaded to improvement of flame retardant properties of APP/DPER/PP intumescent flame retardant materials. The influence of MMT on thermal degradation behavior of APP/DPER and APP was assessed by thermogravimetric analysis (TGA), and the char formation interactions between MMT and APP were investigated by X-ray photoelectron spectrum (XPS). The results show that by adding MMT, the residue of 800°C for APP/DPER and APP are increased by 12.3% and 14.5%, respectively, which mainly is dominated by the interaction between MMT and APP. This interaction leads to the formation of Si-O-P bond, and the decomposition stability of APP at high temperature is increased.