Primary Pyrolysis Products of Hydroxy-Terminated Polybutadiene

This is the first report on the analysis of primary degradation products of a widely used commercial propellant binder, viz. hydroxy-terminated polybutadiene (HTPB), which has been carried out by direct pyrolysis mass spectrometry. The mechanism of degradation involves a radical process forming cyclic compounds as well as β-CH transfer reactions to form linear oligomers. On the basis of heats of formation data, it was found that the formation of 1,3-butadiene monomer is not favored during the primary chain scission process. However, its formation appears to emanate from the dissociation of high molecular weight cyclics/linear oligomers. In the presence of strong oxidizers such as ammonium perchlorate, the degradation pattern of HTPB, as observed in pyrolysis−gas chromatography/mass spectrometry analysis, is significantly affected, indicating its influence on HTPB degradation.