SynopsisThe thermal degradation of metu-and para-linked perfluoropolyphenylenes in uacuo and in oxygen has been studied. Rates of breakdown were determined thermogravimetrically and products of breakdown in vacuum analyzed by using a mass spectrometer. The thermal stability in YUCUO was comparable with that of polyphenylene, and that in oxygen was rather inferior to that of polytetrafluoroethylene. The higher molecular weight polymers gave as the main volatile degradation products silicon tetrafluoride and carbon dioxide, together with a carbonized residue containing virtually no fluorine.
m o r nThe thermal degradation in vacuum of polymers 'containing aromatic or heterocyclic rings linked by various groups has been studied by a weight loss method. The most stable of the polymers examined were those with -CO-, mixed -S& and +, or -SOr linkages. The stability of these were superior to or comparable with poly-p phenylene and poly-m-phenylene. The particular combinations of aromatic nuclei and linking groups used did not result in tractability as most of the polymers were insoluble and infusible, even though of low molecular weight. Substitution in the aromatic nuclei could improve tractability, though a t the expense of thermal stability.
synopsisThe thermal degradation in oxygen of fifteen polymers containing aromatic rings in the chain has been studied by a weight loss method. The relative thermal stabilities of the d~e r e n t polymers have been determined and, where possible, the overall activation energy for breakdown. The results have been compared with those for samples of the same polymers degraded in vacuum. The most thermally stable of the polymers examined under oxidizing conditions was poly(2,6dichlorophenylene oxide), with a stability comparable with that of a copolymer of tetrafluoroethylene and hexafluoropropylene.
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