THE APPLICATION OF MODULATION DIFFERENTIAL SCANNING CALORIMETRY TO THE GLASS-TRANSITION - THEORETICAL-ANALYSIS USING A SINGLE-PARAMETER MODEL

The modulated differential scanning calorimetry (MDSC) technique super imposes upon the conventional DSC heating rate a sinusoidally varying modulation. The result of this modulation of the heating rate is a per iodically varying heat flow, which can be analysed in various ways. In particular, MDSC yields two components ('reversing' and 'non reversin g') of the heat flow, and a phase angle. These each show a characteris tic behaviour in the glass transition region, but their interpretation has hitherto been unclear. The present work clarifies this situation by a theoretical analysis of the technique of MDSC, which introduces a kinetic response of the glass in the transition region. This analysis is able to describe all the usual features observed by MDSC in the gl ass transition region. In addition, the model is also able to predict the effects of the modulation variables, and some of these are discuss ed briefly.