THE ATHAS DATABASE ON HEAT-CAPACITIES OF POLYMERS

Data of thermodynamic properties of polymers have in the past been neglected by main-stream collections. The well-founded reason for this is the common non-existence of equilibrium in polymeric materials. In the meantime, however, extrapolation methods and special polymerization and crystallization techniques have been developed to assess the equilibrium properties of polymers. The ATHAS data bank, for example, contains such equilibrium information on heat capacities from 0 to 1000 K, vibrational spectra, transition parameters, enthalpies, free enthalpies, and entropies for over 200 polymers and polymer-related materials. The availability of such data for polymers proved of great importance for the analysis of metastable states. With reference to the equilibrium limit, stability estimates can be made and detailed studies are possible of the superheating on melting and supercooling on crystallization. Comparisons of the vibrational heat capacities with measured data reveal conformational motion in polymers. A new mesophase, that of condis crystals, could be defined. A new glassy state, the rigid amorphous state, could be identified. For the first time, it became even possible to analyze drawn fibers using a multi-phase approach based on thermal and structural analyses.