The Effect of Sample Temperature Gradients on DSC Thermograms at the Glass Transition Temperature

Abstract

Differential scanning calorimetry is currently being applied with increasing frequency to relatively heavy, and thus thick, samples of a variety of thermally insulating materials.¹ Rationale for such applications are, for example, to reduce noise in measurements of small specific heat changes at the glass transition or to reduce, during measurement, the effects of ongoing processes such as the evaporation of plasticizer. As is shown below, however, surprisingly large temperature gradients typically occur in samples of this kind and, although these gradients do not usually affect the determination of specific heat by differential scanning calorimetry, at the glass transition these large gradients do, in fact, mask the true specific heat variation with temperature.