Characterising the glass transition and relaxation kinetics by conventional and temperature-modulated differential scanning calorimetry

Over the past 20 years or so, considerable research effort has been directe d towards a better understanding of the glass transition in polymers (indee d, of amorphous materials in general), and of the associated relaxation pro cesses, principally by the use of differential scanning calorimetry (DSC). The extent to which phenomenological approaches (e.g. 'curve fitting' and ' peak shift') can describe the response of glasses in DSC is reviewed, and t he degree of enlightenment afforded by these models is discussed. More rece ntly, the technique of temperature-modulated DSC (TMDSC), has attracted con siderable attention, and its application to the glass transition of polymer s is considered here within the framework of the same models as are used fo r conventional DSC. In particular, the two techniques of DSC and TMDSC are compared in respect of the quantitative analysis of the data and in the lig ht of the problems of heat transfer. (C) 1998 Elsevier Science B.V. All rig hts reserved.