Effect of excess enthalpies on binary mixtures containing propylene glycols and poly(propylene glycols) + dimethyl carbonate at 308.15 K

Excess enthalpies have been determined at atmospheric pressure and at 308.15 K over the entire range of composition for binary mixtures containing propylene glycol (PG), dipropylene glycol (DPG), tripropylene glycol (TPG), poly(propylene glycol)-400, -725, -1200, -2000 + dimethyl carbonate (DMC). From the experimetal data, excess enthalpies, HE, and standard deviations in enthalpy, σ(HE) have been calculated. The experimental data were fitted to a Redlich–Kister polynomial to obtain the binary adjustable parameters, ak. The HE values are positive over the entire range of composition, decreasing with the increase of the molecular weight of glycols. The mixtures containing polydisperse glycols behave as regular solutions. Conclusions were qualitatively discussed in terms of molecular interactions.