LASER PYROLYSIS OF POLYMERS AND ITS RELATION TO POLYMER FIRE BEHAVIOR

Laser-pyrolysis time-of-flight mass spectrometry has been applied to t he study of rapid thermal degradation of polymethylmethacrylate (PMMA) and rigid polyurethane foams. The heating rate has little influence o n the mechanism of PMMA degradation. In both the laser and low heating rate experiments, monomer was the major pyrolysis product. Laser pyro lysis of rigid polyurethane foams resulted in the evolution of polypro pylene glycol as the major species together with low molecular weight species such as CO2 etc. It is considered that polypropylene glycol an d its further decomposed species act as fuel for the flame in a real f ire situation. The ratio of polypropylene glycol to CO2 in the evolved gases decreased with the increase of isocyanate index. This is associ ated with the improvement of fire resistance at a high isocyanate inde x. (C) 1997 Elsevier Science B.V.