Overview

In this last Chapter of Thermal Analysis of Polymeric Materials, the link between microscopic and macroscopic descriptions of multi-component macromolecules is discussed, based on the thermal analysis techniques which are described in the prior chapters. The key issue in polymeric multi-component systems is the evaluation of the active components in the system. The classical description of the term component was based on small-molecule thermodynamics and refers to the number of different molecules in the different phases of the system (see Sect. 2.2.5). If chemical reactions are possible within the system, the number of components may be less than the different types of molecules. It then represents the species of molecules that can be varied independently. For example, the three independent species CaO, CO ₂, and CaCO ₃ represent only two components because of the equation that links their concentrations:

More complicated is the mixture of the eight independent species in the four chemical equations:

Together with the material-balance equation, this system is described by only three components in the phase rule given in Sect. 2.5.7.

For macromolecules, the meaning of the term component was already relaxed to account for the fact that small changes in their length do not affect their properties, as discussed in Chap. 6. Similarly, decoupled segments of a polymer chain at a phase boundary may change the accounting for components, as is shown in Fig. 6.69. The main issues in Chap. 7 are the additional problems arising from the size of the macromolecule...