Density and Viscosity of (Ethyl Acetate + Diethyl Succinate) Mixtures: Experimental Measurements and Molecular Dynamics Simulations

In this work, the liquid phase density and viscosity of pure ethyl acetate (ETA) and diethyl succinate (DES), and binary mixtures with DES mole fractions of 0.25 and 0.50 were experimentally investigated at temperatures ranging from 283.15 to 363.15 K and pressures up to 25 MPa using a vibrating-tube densimeter and a vibrating-wire viscosimeter. The expanded relative measurement uncertainties (k = 2, level of confidence = 0.95) were determined to be 0.002 for density and 0.021 for viscosity over the entire measurement temperature and pressure range. Besides, a modified Tait-type equation and Tait-Andrade equation were applied to reproduce liquid densities and viscosities as a function of temperature and pressure. The isothermal compressibility and isobaric thermal expansivity were also derived from this work. Good agreement between experimental data, correlations, and literature data was obtained, with the semiempirical correlations showing good predictive capabilities. Furthermore, molecular dynamics (MD) simulations in an isobaric-isothermal (NpT) and canonical (NVT) ensemble with the modified optimized potential for liquid simulations─all-atom force field (LOPLS FF) were applied to figure out the transport properties and microscopic structures of the examined systems. These simulations showed that LOPLS FF was more pronounced for ester solvents, which could benefit the future study on the development of biofuels and fuel additives.