Investigating ethyl octanoate and alcohol molecular interactions through an extended hard sphere framework

The liquid densities and viscosities of ethyl octanoate (EO) blended with a series of 2-alkanols (2-propanol to 2-hexanol) over a temperature range of 293.15–323.15 K were investigated. Experimental data showed positive deviations from ideal behavior in excess molar volume and negative viscosity deviations in all tested fluids. These deviations in excess volume suggest that the intermolecular forces between EO and the 2-alkanols are relatively weak. A modified rough hard-sphere theory was utilized to model the pure substances and binary liquids viscosity. This approach combines the established transport properties of a smooth hard-sphere system with temperature-dependent hard-core volume and coupling parameters to explain deviations from ideal smooth hard-sphere behavior. Results for pure alkanols and ethyl octanoate within the range of 293–323 K showed a maximum viscosity error of 4.12 % for 2-hexanol. For binary mixtures, the calculated values aligned closely with experimental data, showing a maximum discrepancy of 3.18 % for the EO + 2-hexanol mixture.