DSC is the most widely used of all thermoanalytical techniques. It is used primarily to characterize polymers and organic materials, as well as metals, ceramics, and composites.

Basically the DSC measurement is a function of differential heat flow with temperature for compounds that exhibit thermal transitions. These transitions are typically melting, crystallization, and the glass transition, T_g.. Such measurements provide quantitative and qualitative information about physical and chemical changes that involve endothermic or exothermic processes.

Examples

Detection of Polymorph

The figure to the right is an example of a low temperature DSC scan on a newly synthesized polymer containing carbon, silicon, and oxygen. The glass transition occurs between –130° and –123°C, followed by an exotherm that is thermally-induced crystallization. The crystalline polymer component is stable up to -50°C, where it then melts in a bi-phasic pattern. The detection of this behavior via DSC was the first evidence that the polymer exhibited two distinct crystalline forms.

Crystallization and Supercooling

Accurate recordings of crystallization of a polymer from the melt were desired for an injection-molding application. Previous experience with the polymer showed a tendency to supercool in an unpredictable manner. DSC pans were surfaced etched to provide nucleation sites for crystallization. Subsequent experiments carried out in a programmed heat-cool mode showed conclusively that this phenomenon could be controlled with minimal supercooling.