Pyrolysis of γ-ray irradiated poly(tetrafluorethylene) powder

Pyrolysis of γ-ray irradiated poly(tetrafluoroethylene) powder (PTFE) has been studied at temperatures from 2000C to 3900C in the presence of air. By heating, the weight decrease of the powder and the formation of gaseous CO2 and CO were observed. The weight decrease of the powder increased with total dose of irradiation. γ-ray irradiated PTFE decomposed partly by heating above 2500C. By heating at 3000C, the degree of weight decrease increased with heating time and reached a constant value. While at 3900C, successive decomposition was observed. The melting point of PTFE was depressed by irradiation, while it did not change by heating. No change of IR spectrum of PTFE by irradiation and/or heating was observed. In the irradiated PTFE, stable peroxy radical was observed by ESR measurement at room temperature, but decreased by heating at 1500C and disappeared at 2500C. Upon pre-heating the irradiated PTFE above 2000C, the weight decrease of the powder at 3900C decreased remarkably. On the basis of these results, mechanisms of the pyrolysis and thermo-stabilization of the irradiated PTFE were discussed. (auth.)