Thermodynamic properties of triethylamine + water liquid mixture from shear viscosity measurements

Densities ρ and viscosities η, for the binary mixture triethylamine–water have been measured over the entire range of mole fractions at different temperatures, both near and far away from the critical temperature Tc (0.076 K ≤ (T − Tc) ≤ 8.276 K). By calculating the corresponding activation parameters ΔH* and ΔS*, it has been shown that a possible connection may be presented between the evolution of these parameters and the critical region. Furthermore, in the one-phase region just below Tc of the critical (TEA–W) binary fluid, the viscosity measurements yield an enhancement as expected for Ising criticality with a crossover to regular behaviour. The regular background is obtained by interpolation from the measurements at non-critical concentrations. Shear viscosity data are consistent with a power law divergence η = η0(Qξ0)zt−yF predicted by the mode-coupling and the dynamic renormalization group theories. Different equations are used in order to determine the critical exponent y, the obtained values are in good agreement with the renormalization group-predicted value. The best fit gives y = νz = 0.0391 ± 0.0002 (i.e., z = 0.0679). Moreover, the resulting value for the wave number Q = 1.0152 ± 0.0016 nm−1 is in the region found for many other systems.