The glass transition temperature of polymer-diluent systems

The theoretical treatment proposed by Couchman to describe the compositional dependence of T, for polymer-diluent systems has been applied, in its several forms, to selected pairs for which heat capacity data are found in the literature. The most accurate equation gives the least satisfactory description of the experimental T, data. This result seems to be accounted for by the assumption, first suggested by Couchman, that in some cases the entropy of mixing is not continuous at Tg.