Thermoplastic polyurethanes as carbonization agents in intumescent blends.Part 2: Thermal behavior of polypropylene/thermoplastic polyurethane/ammonium polyphosphate blends

Melt blending of thermoplastic polyurethane (TPU)/ammonium polyphosphate (A PP) additives in a polypropylene matrix improves fire properties of the pol ypropylene-based materials via an intumescence process. In this study, the protective effect of intumescence is studied considering the thermal stabil ity of a particular FR PP/TPU/APP blend in the conditions of its thermo-oxi dative degradation. Thermogravimetric analysis allows the computation of the degradation rate o f a particular system using the Invariant Kinetic Parameters method. The st udy shows that a reaction between APP and TPU leads to the formation of the intumescent shield and gives a material with improved thermal stability. F inally, we present the computed temperature of the degradation front of the blend that is proposed as a probe for the estimation of the fire retardanc y.