Glass transition of poly(ethylene terephthalate)

It has been found that commercial poly(ethylene terephthalate) film exhibits current glow curves which have maxima at 73.5 ± 3.4°C and at 105.3 ± 3.4°C. These current glow curves were obtained by measuring the current flowing under zero bias as the temperature was raised 1°C/min. A typical curve, for untreated 1-mil du Pont Mylar A, is seen in Fig. 1. Although a paper on this study will shortly be submitted for publication, some conclusions of that paper may be stated here.