Mechanisms of pyrolysis of fluoropolymers

Abstract

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 OCF 3 groups into perfluoropolymers in place of F atoms brings about significant changes in their mode of degradation. The OCF 3 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 OCF 3 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.