Thermophysical Properties of Binary Mixtures of n-Dodecane with n-Alkylcyclohexanes: Experimental Measurements and Molecular Dynamics Simulations

Abstract

Thermophysical properties (densities, speeds of sound, bulk moduli, and viscosities) of binary mixtures of n-dodecane with n-alkylcyclohexanes (propyl- to dodecylcyclohexane) were examined at various compositions and temperatures (293.15–333.15 K). Viscosities were analyzed using the McAllister three-body equation, and excess molar Gibbs energies of activation for viscous flow (ΔG*E) at 293.15 K were calculated. Because the ΔG*E values did not differ significantly from zero, the mixtures appear to behave ideally. In contrast, nonzero excess molar volume values obtained both experimentally and using molecular dynamics (MD) simulations suggest nonideal behavior. Excess molar volumes were the most negative for n-dodecylcyclohexane mixtures and increased with decreasing alkyl side-chain length eventually becoming slightly positive for mixtures containing n-propylcyclohexane. MD simulations were able to predict density, isentropic bulk modulus, and dynamic viscosity values, but the accuracy of the calculated d...