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

Abstract

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 T c (0.076 K ≤ ( T − T c) ≤ 8.276 K). By calculating the corresponding activation parameters Δ H* and Δ S*, 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 T c 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 = η 0( Qξ 0) z t − y F 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.