Characterization Of Polyurethane Research Articles

Characterization of polyurethanes by high-resolution pyrolysis-capillary gas chromatography

Several types of polyurethanes were studied by pyrolysis-gas chromatography with a fused-silica capillary column. Polyurethanes were found to be thermally degraded through dissociation of urethane linkages followed by cleavage at ester linkages at elevated temperatures. As a result, diisocyanates, dienes, cyclic compounds, mono-ols and diols and some larger fragments with ester linkages were observed on the pyrograms. Both diisocyanate and polyol moieties in a polyurethane could be readily identified on the observed pyrograms. However, the liberated diisocyanates, especially diphenylmethane p,p′-diisocyanate, was not completely recovered on the pyrograms mainly because of recombination reactions with other fragments. On the other hand, urea linkages when thermally cleaved gave characteristic amines in addition to isocyanates. Moreover, the relative peak intensities of diisocyanates were quantitatively correlated with the contents of the diisocyanates in the polyurethanes.