Thermodynamic properties ofN,N-dimethylformamide + water

The excess viscosities, ηE, and excess energy of activation (ΔΕη)Ε of dynamic viscosity have been investigated by using dynamic viscosity measurements for N,N-dimethylformamide + water (DMFW) mixtures over the entire range of mole fractions at five different temperatures. The results were also fitted with the Redlich–Kister equation. This system exhibited very large positive values of ηE and (ΔΕη)Ε due to the increased dipole–dipole interactions and correlation length between unlike molecules. The activation parameters ΔΗσ and ΔSσ have been also calculated, and they show that the critical region has an important effect on the dynamic viscosity properties. The results obtained are discussed from the viewpoint of the existence of interactions between the components.