Calorimetric study of the conformational relaxation times in polystyrene

The temperature dependence of the relaxation times of the structural relaxa tion process of polystyrene is determined by temperature-modulated differen tial scanning calorimetry (TMDSC) and by conventional differential scanning calorimetry (DSC) in the latter by modelling the experimental heat capacit y curves measured in heating scans after different thermal histories. The g ood agreement between both measuring techniques in the temperature interval just above the glass-transition temperature is a guide for the interpretat ion of the results of the TMDSC technique in the glass-transition region. I n addition, the same model applied to DSC scans is used to simulate the TMD SC experiment and the calculated response is compared with the measured sca ns.