Abstract :
The thermodynamic description of polymeric systems is summarized based
on 50 years of gathering experimental information with adiabatic, differentialscanning,
and temperature-modulated calorimetry. This experience has led to a description
of macro- to micro- to nano-phases with macromolecules able to traverse
the phase boundaries and decouple at the surfaces, resulting in different thermodynamic
properties for the separated parts of the molecule. A typical thermodynamic
characterization of semicystalline polymers is that of a globally metastable system
with locally reversible processes. Unique phenomena in polymers include the ability
of semicrystalline polymers to undergo cold crystallization and molecular nucleation,
possess thermally generated point defects and rigid-amorphous fractions, and have
amorphous to mesophasic to crystalline macroconformations with glass, ordering,
and disordering transitions in all three structures. To describe such multifaceted systems,
special combinations of equilibrium, and irreversible thermodynamics as well
as statistical and quantum mechanics are necessary. Only then is it possible to handle
violations of phase rules, changes of properties when approaching nanophase
dimensions, local reversibility, and enthalpy relaxation. The enthalpy relaxation in
polymers originates in the cooperativeness of conformational motion and the iInterferences
of processes of different time scales. The experiments to identify the effects of
