Factors affecting the thermal stability of polytetrafluoroethylene

Abstract

The structure and kinetics of thermal decomposition of polytetrafluoroethylene suggested several methods for improvement of its stability: (a) polymerization in the presence of fluorocarbonn catalysts or photochemically to eliminate labile centers for initiation, (b) inclusion of foreign structural units in the polymer to promote chain transfer of the free radicals active in depolymerization, (c) inclusion of foreign molecules capable of promoting chain transfer. The catalysts tried included perfluorodimethylmercury, perfluoromethyl iodide, and f uorine gas, as well as conventional catalysts. The foreign structural units and additives included sulfur, selenium, and a variety of hydrocarbon and fluorocarbon groups, mainly aromatic, added usually as dibromides to the polymerizing mixture. None of the experimental catalysts or additives brought about any change in the rate of thermal decomposition.