Fire Safety Science Digital Archive

Details are given of a method for the decomposition of small quantities of polyurethane foam and the collection and direct analysis of a highly toxic bicylic phosphorus compound (termed TMPP) produced from the thermal decomposition of foams containing trimethylol propane polyols in combination with phosphorus-containing additives. A range of typical cornrnercial flexible and rigid polyurethane foams and polyisocyanurates available in the United Kingdom up to and including the period of 1974 to 1975 when the problem was first identified by bioassay tests, have been tested for potential TY~P release. Flexible and rigid polyurethane foams yield zero to 0.004 and zero to 0.003 weight per cent conversion of foam to TMPP respectively at 500C. The polyisocyanurate foams show two distinct ranges of zero to 0.003 and 0.1 to 0.15 weight per cent conversion. A detailed study has been carried out with the polyisocyanurate foams which fall in the high yield range to monitor the temperature dependence of TMPP production in both nitrogen and air atmospheres. The optimum temperature of formation is 600C in nitrogen and 500C in air. The maximum temperature at which TMPP is released is about 800C in nitrogen and 700C in air which is consistent with the thermal stability of TMPP obtained during direct experiments with TMPP alone. This work is of a laboratory nature and supplements other work being carried out internationally to evaluate the overall hazard associated with the release of TMPP from foams under fire situations.