Thermal degradation and fire performance of new phosphonate polyurethanes

The thermal degradation and fire behaviour of new phosphonate polyurethanes have been studied by thermogravimetric analysis and by measurement of limiting oxygen index (LOI). It has been shown that the fire retardant incorporated in the prepolymer chain increased LOI. In connection with the thermal ageing, it has been shown by an electronic probe mass analyser (EPMA) that. the phosphorous molecules included in the polymer remained homogeneously distributed in the material after 3 h of isothermal degradation at 220 degreesC. During the thermal degradation, the phosphorous molecules form a protective layer on the polymer surface, increasing the polyurethane thermal stability. The low molecular weight organic products released during the thermal degradation allow dilution of the formed gases. (C) 2002 Elsevier Science Ltd. All rights reserved.