In this study, dielectric relaxation spectroscopy experiments were carried out during heating in the a relaxation region of PET. The results for low heating rates were consistent with isothermal measurements. Moreover, the results expressed as a function of temperature were much clearer than those expressed as a function of frequency. However, the loss peaks obtained in these non-isothermal experiments showed a systematic shift on the temperature axis when the heating rate increased. A significant but nearly constant thermal lag was observed in experiments with heating at 1 K min ⫺1 when using different equipment. It appears that isothermal data obtained in a well calibrated apparatus can be used to adjust the temperature axis of dielectric results obtained in ramp temperature experiments.
Посилання на статтю:
Comparing dielectric measurements on poly(ethylene terephthalate) at constant heating rates with isothermal measurements / Madalena Dionı́sio, Natália M. Alves, João F. Mano // Polymer. – 1999. – N 40. – P. 2675–2679.