Characterization of cured polysulfide polymers by thermal degradation: Pyrolysis-GC and thermogravimetric studies

Polymers prepared by curing thiol-terminated liquid polysulfide polymer [HS(RS₂)_nRSH, R = ? CH₂CH₂OCH₂OCH₂CH₂? ] with p-quinonedioxime, PbO₂, and MnO₂ were studied by pyrolysis-GC and thermogravimetry. Characteristic differences were observed in the composition of the pyrolyzates under flash pyrolysis at 420 and 470°C. The concentration of the cyclic monomer, 1,3-dioxa-6,7-dithionane, in the pyrolyzates was found to vary considerably from polymer to polymer. The change in mechanism with the extent of degradation and the corresponding overall activation energies were evaluated by thermogravimetry. The pyrolysis-GC and thermogravimetric data were shown to provide partial characterization of the substrates. Mn appears to be in a coordinated complex in the MnO₂-cured polymer.