Mechanisms of pyrolysis of fluoropolymers

A systematic study of the mechanisms of the pyrolysis of fluoropolymers was made by means of pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and direct Py-MS. For perfluoropolymers and chlorine-containing fluoropolymers the depolymerization reaction predominates during pyrolysis. However, the introduction of OCF3 groups into perfluoropolymers in place of F atoms brings about significant changes in their mode of degradation. The OCF3 groups activate the F atoms attached to the same carbon atoms and make them easier to transfer. Therefore, random chain cleavage accompanied by the F transfer becomes predominant in the course of the pyrolysis. When the F atoms of perfluoropolymers are partly replaced by H atoms, elimination of hydrogen fluoride and chain cleavage accompanied by H transfer would occur with great ease. For fluoropolymers containing H, Cl and OCF3 as side groups, the depolymerization, the elimination of hydrogen chloride and hydrogen fluoride and the random chain cleavage accompanied by H and F transfer would occur simultaneously and compete with each other.