High-pressure and -temperature viscosity measurements of methanol and 4:1 methanol:ethanol solution

Viscosity (eta) measurements using rolling sphere viscometry in a resistance-heated diamond-anvil pressure cell yield activation energies of 18-98 kJmol over a pressure range of 1.1-6.1 GPa for methanol and 26-78 kJmol over a pressure range of 2.9-5.4 GPa for a 4:1 methanol:ethanol solution. Nonlinear models of log eta (free-volume and power-law models) yield statistically better fits than the Arrhenius model at room temperature and extrapolate to lower glass-transition (10(12) Pa s) pressures. Glass-transition pressures for the free-volume model change little over the temperature range studied (298-338 K), whereas the power-law values converge to those of the Arrhenius model at temperatures above 320 K.