Note: Enthalpy relaxation studies in amorphous poly(ethylene terephthalate) by Modulated DSC

Abstract Physical aging in amorphous poly(ethylene terephthalate) (PET) was studied by means of modulated differential scanning calorimetry (MDSC). Two different thermal histories were used: (1) quenching from above the Tg to 0°C; (2) slow cooling at l°C/4 min from above the Tg to just below the Tg . The enthalpy relaxation of the amorphous PET is affected by thermal histories induced by annealing below Tg. The data showed that all the parameters describing the relaxation process (ΔH Tmax , and Tons ) were strongly dependent on the thermal histories of the sample before annealing. The magnitude and position of the endothermal peak are enhanced in the order slow cooling quenching.