Abstract
Abstract Excess molar enthalpies, H m E , were determined as a function of molar fraction at 308.15 K and at atmospheric pressure for the binary mixtures containing propylene carbonate with ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, poly(ethylene glycol)-200, poly(ethylene glycol)-300, poly(ethylene glycol)-400, and poly(ethylene glycol)-600. Values of H m E range from a maximum of about 1640 J mol −1 (propylene glycol) to a minimum of about −386 J mol −1 (PEG-600). All mixtures containing monodisperse glycols have positive values of H m E . Also PEG-200 presents a curve of H m E versus x 1 (the molar fraction of glycol, component 1) always positive, whereas PEG-600 presents negative values of the heat of mixing over the whole range of the molar fraction. Finally, PEG-300 and PEG-400 show an inversion of sign of H m E , at about x 1 =0.7 and 0.3, respectively. The experimental data were correlated using the Redlich–Kister polynomial and the adjustable parameters were obtained by the least-squares method. A qualitative discussion have been made in terms of intermolecular H-bonds.
Published Version
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