Effect of temperature and solvents on ultrasonic speed and related acoustical thermodynamic parameters of epoxy resin of (2E,6E)-bis(4-hydroxybenzylidene)cyclohexanone solutions

Abstract

The density (ρ), viscosity (η) and ultrasonic speed (U) of pure solvents: 1,4-dioxane (DO), tetrahydrofuran (THF), chloroform (CF) and (2E,6E)-bis(4-hydroxybenzylidene)cyclohexanone (EBHBC) solutions of different concentrations were investigated at four different temperatures: 298, 303, 308 and 313 K to understand the effect of solvents on molecular interactions in these solutions. Various acoustical and thermodynamic activation parameters such as specific acoustical impedance (Z), adiabatic compressibility (κa), Rao’s molar sound function (Rm), van der Waals constant (b), internal pressure (π), free volume (Vf), intermolecular free path length (Lf), classical absorption coefficient (α/f2)cl, viscous relaxation time (τ), Gibbs free energy of activation (ΔG*), enthalpy of activation (ΔH*) and entropy of activation (ΔS*) were determined using the ρ, η and U data and correlated with concentration (C) at different temperatures (T). Very good to excellent correlation between a given parameter and concentration is observed at different T. Linear/nonlinear increase or linear/nonlinear decrease in acoustical parameters, solvation number and thermodynamic activation parameters suggested structure-forming tendency of EBHBC in the selected solvent systems.