Temperature and composition dependence of viscosity. II. Temperature dependence of viscosity of propylene carbonate-dimethoxyethane mixtures

The application of the currently used equations for the reproduction of the temperature dependence of viscosity η of binary solvent mixtures of propylene carbonate (PC) and dimethoxyethane (DME) favors the choice of the Vogel-Fulcher-Tammann (VFT) equation using the ideal glass transition point as the reference temperature T_o for the estimation of free and blocked (inaccessible) volumes. Reduced plots show that the free volumes as obtained from the VFT equation mainly determine the viscosities of the liquid mixtures; the blocked volumes V_x(T_o)≡V_o (x: mole fraction of PC) show ideal behavior. The effect of negative excess volumes V ^E on viscosity, studied in the preceding paper, is examined in comparison with the effect of a temperature decrease. The equal signs of η ^E and V ^E can be explained by referring the viscosities to the reference temperature T_o.