RADIATION DEGRADATION OF FLUOROPOLYMERS - CARBOXYLATED FLUOROPOLYMERS FROM RADIATION DEGRADATION IN PRESENCE OF AIR

Irradiation of PTFE by accelerated electrons in the presence of air gives rise to a carboxylated structures at doses above 50 kGy. The surface of the irradiated suspension polymerizate TF 1750 is more carboxylated than is the bulk. The influence of oxygen content and radicals is much higher than it is with the emulsion polymerizate TF 2025. The melting point of irradiated PTFE increases at low doses. Electron-beam irradiation of the fluorinated copolymers perfluoroalkoxy (PFA) and tetrafluoroethylene-hexafluoropropylene (FEP) leads to loss of fluorine. In all cases, the oxygen uptake was higher near the surface than in the bulk. PFA was better carboxylated than was FEP. The fact that cross-linking was not found to a measurable extent up to 800 kGy suggested that double-bound formation was important. The main effects of electron-beam irradiation are chain scission, oxidation, and unsaturation depending on dose rate, oxygen content, and particle size.