The thermal degradation of some fluorine-containing elastomers

Polymers containing both hydrogen and fluorine atoms can give rise to the evolution of hydrogen fluoride (HF) on thermal and thermo-oxidative degradation. This evolution has been studied with the aid of a fluoride ion specific electrode. The effect of formulation has been examined in some detail for a hydrofluoro-elastomer and it has been shown that the yield of HF is greatly affected by changes in formulation. The effect of variation in chemical structure has also been studied by comparing the degradation of hydrofluoro-, perfluoro-, phosphazene- and fluorine-containing siloxane elastomers. The perfluoro elastomer is the most stable, and the phosphazene elastomer the least stable of the polymers examined, although they both give low yields of HF.