Ultrasonic Speed and Thermodynamic Parameters of Novel Epoxy Resin Solutions Based on Cardo Symmetric Double Schiff Bases at 308.15 K

The density, viscosity and ultrasonic speed (2?MHz) of several pure solvents: chloroform, THF, and 1,4-dioxane, along with epoxy resin solutions, have been investigated in order to understand the effect of solvents on molecular interactions in these systems at 308.15?K. Various thermodynamic parameters such as the ultrasonic speed (U), adiabatic compressibility (?? _?? ), Van der Waals constant (b), internal pressure (??), intermolecular free path length (L _f), and viscous relaxation time (??) have been determined and correlated with the concentration (C). Good-to-excellent correlations are observed between a given parameter and the concentration. Linear or nonlinear increases or decreases of thermodynamic parameters with concentration indicated the existence of strong molecular interactions in the solutions. Gibb??s energy of activation was found to be dependent on the concentration, nature of the solutes, and the solvents used.