Viscosities and Activation Energies of Viscous Flow of the 1,2-Ethanediol/N,N-Dimethylformamide Binary Solvent System

Densities (ρ) and absolute viscosities (η) of pure 1,2-ethanediol, N,N-dimethylformamide and of their nine mixtures were determined at nineteen temperatures ranging between −10 and +80 °C. The above properties were fitted by empirical equations stating their dependence on temperature and composition of the mixtures. The extrathermodynamic excess functions, such as the excess rheochor [RE] and the excess Gibbs energy of activation of viscous flow ΔGE, have been studied. The trend of [RE] vs. composition of the mixtures shows negative deviations from ideality, indicating extensive molecular interactions between the components of the binary solvent system. Furthermore, activation enthalpies and entropies for viscous flow have been obtained and their variations with composition have also been discussed.