ABSTRACT
In previous chapters, the principles and applications of differential scanning calorimetry (DSC) have been outlined, and it should be clear that the technique is both versatile and extremely sensitive. Using DSC, it is possible to analyze a wide range of systems quickly and cheaply so that thermodynamic parameters may be obtained. These qualities have led to the widespread use of DSC for not only pure research but also for routine thermal analysis. DSC does, however, have some drawbacks. To achieve good thermal contact with a sample, most DSC instruments are equipped with a pair of sample holders into which prepared sample and reference materials are placed. These materials are usually encapsulated in crimped aluminum ampoules, a typical sample mass being 5 to 10 mg. Such a small mass of sample contributes
to a good thermal contact between the instrument and the sample and ensures there are no temperature gradients within the ampoule. For dilute samples, compounds with higher molecular weights such as proteins or polymers, or reactions with a small change in reaction enthalpy (
Δ
H
)
;
however, such a small sample mass may preclude the use of DSC, as the magnitude of the heat flow to or from the sample during a reaction may be lower than the detection limit of the instrument. To study such systems it is necessary to use high-sensitivity differential scanning calorimetry (HSDSC), a derivative of DSC. This chapter focuses on understanding the principles and applications of this technique.
