Thermoplastic polyurethanes as carbonization agents in intumescent blends. Part 1: Fire retardancy of polypropylene/thermoplastic polyurethane/ammonium polyphosphate blends

This work deals with the fire retardancy of polypropylene (PP)/thermoplastic polyurethane (TPU)/ammonium polyphosphate (APP) intumescent blends, using TPU with different chemical compositions and structures. The influence of the chemical nature of the polyol used in the synthesis of the TPU on the fire resistance of materials is discussed. Moreover, smoke production from combustion of the blend and mechanical properties (elongation/stress relation) of the polymeric materials are studied. Improved flame retarded (FR) materials with very different mechanical properties according to the composition of the TPU can be formulated.