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)/thermoplasti c 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 f ire resistance of materials is discussed. Moreover, smoke production from c ombustion of the blend and mechanical properties (elongation/stress relatio n) of the polymeric materials are studied. Improved flame retarded (FR) mat erials with very different mechanical properties according to the compositi on of the TPU can be formulated.