Theory of Differential Scanning Calorimetry — Coupling of Electronic and Thermal Steps
A model system for differential scanning calorimetry (DSC) is developed in which the electronic response of the instrument is coupled with the heat flow across an interface. Equations are derived which relate the time constants for this two-step process with the thermal properties of the sample and the amplitudes, areas, slopes and dwell times of DSC traces. The cases discussed include first and second order transitions, partial and total “supercooling” and effects of a temperature dependence of the heat capacity and the rate of temperature change. The magnitude of the lag terms of these cases is determined from typical experimental data. The equations permit an independent determination of the interfacial time constant and an assessment of the limits for the validity of the theoretical model.
KeywordsDifferential Scanning Calorimetry Heat Capacity Order Transition Differential Scanning Calorimetry Trace Heat Capacity Change
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