Thermoluminescence and Phase Transitions of Irradiated Fluorinated Polymers

Polytetrafluoroethylene and polytetrafluoroethylene oxide have been irradiated under vacuum and in the presence of oxygen and helium. The thermoluminescence glow curves of the polymers have been examined from liquid-nitrogen temperatures up to about 60°C. The polymers irradiated in vacuo show very weak thermoluminescence emission. The presence of gas during irradiation has the effect of inducing a strong emission. The temperature of the thermoluminescence peaks coincides with the appearance of molecular motions. The spectral distribution of the thermoluminescence glow peaks has been determined. The results have been interpreted on the basis of the electron-trap theory. It is suggested that thermoluminescence at low temperature is associated with a continuous structural change in the amorphous regions which occurs on warming the polymers and that the trapping levels are uniformly distributed over a wide range of energy. The thermoluminescence glow peaks near room temperature correspond to well-defined crystalline transitions in the two polymers.