Partially crystalline plastics have small crystallites in which the chains are highly ordered in relation to each other. At a correspondingly high temperature, these domains melt. This melting process is an enthalpic process for which the corresponding melting enthalpy must be applied. This is expressed in the DSC curve by a peak at a characteristic temperature.

Amorphous and semi-crystalline plastics have a transition temperature above which the chains become mobile in relation to each other. This is the so-called glass transition temperature. The mobility of the chains increases the heat capacity of the plastic, which is expressed by a step in the DSC curve. The glass transition temperature is polymer-specific and allows a characterisation of the plastic.

In addition to the melting temperature, the polymer-specific enthalpy of fusion can be determined by integrating the peak areas in the DSC curve. By comparison with literature data, the degree of crystallisation in the plastic can be determined.

The crystallisation temperature and enthalpy are determined from the DSC cooling curve. When the crystallisation temperature is undershot, the chains form highly ordered domains. This process is opposite to the melting process and exothermic. This released energy is recorded by the DSC.

Plastics that are not fully cured can also be analysed using DSC. The exothermic processes to be investigated are initiated at elevated temperature and the heat of reaction released is determined. This allows statements to be made about the conversion, the required reaction temperature and the enthalpy of reaction.