Studies on the thermal behavior of polyurethanes

The number of fires appear to be increasing all over the world with some big fires started from burning sofa polyurethane foam (PUF). The general public is quite concerned about the risk of fire due to the extensive use of polyurethane-based materials. Better understanding of the fire behavior of the materials would provide guidelines on fire safety provision. The first step is to review the thermal decomposition mechanisms of polyurethane under different environmental conditions, which will be reported in this paper. Recent studies on the thermal decomposition kinetics and thermal stability of polyurethane are described. Thermal decomposition and combustion reactions of polyether-polyurethane and polyester-polyurethane in air and nitrogen atmospheres investigated by using thermogravimetry analysis will then be outlined. The kinetic processes of polyurethane decomposition studied by the model fitting method are discussed. Polyester-polyurethane was found to be thermally more stable than polyether-polyurethane. The presence of oxygen would significantly affect the breaking down of the polymeric chains. Fire retardants for polyurethane are also briefly reviewed. Results are useful for developing fire retardants for polyurethane-based materials with better fire behavior.