Experimental and theoretical evaluation of interactions in liquid mixtures consisting bio-based solvent and 2-alkoxyethanols through viscometric study

Viscometric properties provide a deep and meaningful insight of the various interactions taking place in binary liquid mixtures. Recently, bio-based solvents have been either employed directly as green solvents or as a key component for the production of new solvent systems that are potentially less toxic and more bio-compatible. In this paper, we report experimental values of dynamic viscosity (eta) for binary systems of bio-based solvent (gamma-valerolactone) with 2-alkoxyethanols at different temperatures (298.15-313.15 K; interval, 5 K), covering the whole composition range under atmospheric pressure of 0.1 MPa. On the experimental basis, kinematic viscosity (nu), viscosity deviation (Delta eta) and excess Gibbs free energy of activation for viscous flow (Delta G*E) have been calculated. The derived properties, Delta eta and Delta G*E were fitted to Redlich-Kister polynomial equation to obtain binary adjustable parameters and standard deviations between experimental and estimated values. Further, the viscosity-composition data have been correlated with various approaches including no adjustable parameter (Bingham, Arrhenius, Kendall and Kendall-Monroe), one adjustable parameter, (Grunberg - Nissan, Hind et al. and Katti-Chaudhri), two adjustable parameter (McAllister three-body and Heric-Brewer) and three adjustable parameter (McAllister four-body and Jouyban-Acree) relations. Moreover, for all the predicted viscosity values, the standard deviation percentages (sigma%) were calculated to compare the quality of correlations with experimental data. Furthermore, the Graph theory was employed to correlate experimental Delta eta values and to analyse the patterns of molecular aggregation in the studied mixtures. The DFT calculations were also performed in the support of graph theory. The observed Delta eta data suggests that the dissociation of self-associated structures of pure components is more dominating factor than hetero-association for all the studied binaries.