An outline of DSC theory

The sample, S, is located in a small calorimeter and the reference, R, (usually an inert substance of similar heat capacity) is located in another. In a conventional calorimeter, the heat capacity of the system Cp is measured from the temperature rise accompanying a known amount of (electrical) energy input into a system at constant pressure. 

There are several different types of instrument covered under the term DSC, which have evolved from differential thermal analysis (DTA) and measure the temperature difference between sample and reference pans located in the same furnace. This is then converted to heat flow using a calibration factor. A detailed analysis of DSC requires consideration of the various sources of heat loss, and these are generally captured in the calibration routine for the instrument. Absolute temperature calibration is achieved through the use of pure indium (156.6 °C) and tin (231.9 °C) melting-point standards. A comprehensive analysis of the theory of DSC contrasted with DTA may be found in several reference works (Richardson, 1989, Gallagher, 1997). 

A more recent development is temperature-modulated DSC (Jones etal, 1997), which is a particular example of the broader area of modulated calorimetry (Gmelin, 1997) and enables deconvolution of kinetic and thermodynamic processes during the reactive curing of polymer networks (Van Assche et al, 1997). This is discussed in more detail later (Section 3.2.3). 

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