Thermophysical and Spectroscopic Investigation of Binary Mixtures of Cumene with Pentan-1-ol and Hexan-1-ol at Temperatures from 298.15 to 323.15 K
Abstract
Densities (ρ) and viscosities (η) of binary mixtures of cumene with pentan-1-ol and hexan-1-ol were measured over the full composition range at (298.15–323.15) K and 0.10 MPa. From these experimental data, excess molar volumes (VmE), partial molar volumes (V̅i), viscosity deviations (Δη), isobaric thermal expansivities (α) and their excess values (αE), and excess Gibbs free energies of activation for viscous flow (ΔG≠E) were calculated to elucidate the nature of intermolecular interactions. For both systems, VmE values were mostly positive, whereas Δη and ΔG≠E were negative, indicating disruption of alcohol self-association, volume expansion upon mixing, and reduced resistance to viscous flow. The magnitude of VmE increased with temperature but decreased with alcohol chain length, reflecting stronger dispersive contributions in the hexan-1-ol system. FT-IR spectra of equal-volume mixtures showed blue shifts (∼25–26 cm–1) in the O–H stretching band, confirming hydrogen-bond weakening and possible weak O–H···π interactions. Excess properties were well correlated by the Redlich–Kister equation, while the Jouyban–Acree model accurately represented ρ and η. Among the viscosity models examined, the Ausländer and McAllister four-body models provided the best performance.