An investigation of the thermolysis mechanism of model urethanes

The products of pyrolysis in a helium atmosphere of a model urethane foam based on PAPI and propoxylated trimethylol propane were investigated by using GC/MS and GC/CIMS. Chemical-ionization mass spectrometry was used because it produces primarily protonated molecular ions (M + 1) with little fragmentation which facilitated the identification of the polyol decomposition products. Identification of the polyol pyrolysis fragments has led to the formulation of a detailed polyol thermolysis mechanism. This mechanism shows the polyol to decompose by a systematic route of reactions rather than by a random breakdown.