Differential scanning calorimetry heat exchanges

Differential scanning calorimetry (DSC) can be performed in heat compensating calorimeters (as the adiabatic calorimetry), and heat-exchanging calorimeters (Hemminger, 1989 Speyer, 1994 Brown, 1998). 

When a material is heated or cooled, there is a change in its structure or composition. These transformations are connected with a heat exchange. Differential scanning calorimetry (DSC) is used for measuring the heat flow into and out of the sample, as well as for determining the temperature of the thermal phenomenon during a controlled change of temperature. The first method developed by Le Chatelier in 1887 was differential thermal analysis (DTA), where only the temperature induced in the sample was measured. 

Differential thermal analysis (DTA) and differential scanning calorimetry (DSC) are the most widely used thermal analysis techniques. Both techniques have the same objective to examine thermal events in a sample by heating or cooling without mass exchange with its surroundings. The thermal events examined by DTA and DSC include solid phase transformation, glass transition, crystallization and melting. Differential emphasizes that analysis is based on differences between sample material and a reference material in which the examined thermal events do not occur. 

In calorimetry techniques, enthalpy changes accompanying physical or chemical events, whether they are exothermic or endothermic, are measured and monitored either as a function of temperature or time. Thus, a calorimeter is able to collect a heat flux exchanged between the sample and the sensible part of the apparatus, generally made of thermocouples, and to register it. The result is a profile of the rate of enthalpy change, either as a function of temperature as the sample is heated at a known linear rate in differential scanning calorimetry (DSC), or as a function of time when the calorimeter is held at constant temperatnre in isothermal differential calorimetry (DC). 

Differential scanning calorimetry allows measurement of the heat exchanged between a sample (S) and a reference (R). The solidification and melting of phases induce the release and absorption of energy, respectively, and consequently are... 

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