The deviation from ideal behavior in mixtures of propylene glycol and propylene carbonate at different temperatures: Experimental results and modeling

The molecular interactions within a liquid mixture reflect the degree of nonideality present in the solution. This nonideality can be evaluated through various solution properties, including density, viscosity, and refractive index. A comprehensive analysis of these properties offers valuable insights into the interactions between molecules in the mixture. The advancement of models and the validation of theories depend on the precision of these interpretations. This study presents experimental data on the density, refractive index, kinematic viscosity, and dynamic viscosity of a binary liquid mixture comprising propylene glycol and propylene carbonate. The experiments cover a complete range of solution mole fractions at different temperatures. Density data were correlated using the Peng-Robinson and CPA equations of state, yielding binary interaction parameters. The Eyring equation, combined with the NRTL activity coefficient model, was used to correlate kinematic viscosity data, also resulting in binary interaction parameters. Furthermore, the predictive capability of the Lorentz-Lorenz N-mixing rule was assessed for the refractive index data. The deviations from ideal behavior, as indicated by excess molar volume, variations in viscosity, and changes in refractive index, can be attributed to the formation and breaking of hydrogen bonds between the molecules of propylene glycol. The models employed demonstrate a strong capacity to accurately represent the experimental data.