Differential scanning calorimetry study on intermolecular interactions in polymer–diluent blends involving polyisoprenes and dimethyl terephthalate

The classical expression for estimating the polymer-solvent interaction parameter χ from melting point data of the solvent is refined by considering χ to be concentration-dependent. Differential scanning calorimetry (DSC) measurements are performed on blends of cis-polyiso-prene-dimethyl terephthalate (DMT) and trans-polyisoprene–DMT. It is found that the presence of DMT would not affect the DSC events of the polyisoprenes appreciably. However, in both cases, the melting point of DMT decreases, and the rate of depression increases with increasing proportions of polymer. These DSC data are analyzed by the proposed procedure. The results on the interaction energy density parameter are presented as a function of the blend concentration, and rationalized by the specific interactions between different moieties on the component molecules. The limitations of the present technique are discussed.