The thermal characterization of multi-component systems by enthalpy relaxation

The phenomenon of enthalpy relaxation of amorphous glassy polymers has been developed into an analytical tool which can be applied to elucidate phase behavior and morphologically related phenomena of multi-component systems. We have both reviewed the experimental details concerning its application, using differential scanning calorimetry (DSC), and analyzed the theoretical basis for the effectiveness of the technique within the framework of the description by Moynihan and co-workers of relaxation in glassy systems. A summary of the adaption of this model, together with some new relevant examples, to mimic the experimental response of a multi-phase system is also presented. Although the technique was developed initially to examine phase phenomena in mixtures where behavior was difficult to resolve, owing to a close proximity of respective glass transition temperatures, we also document its evolution in addressing different situations including interfacial phenomena in semi-crystalline/amorphous polymer mixtures and block copolymers. Future directions for application of the technique are also briefly considered.