An insight into the dynamic crossover phenomenon in alcohols from the fluidity equation

Recently, we have introduced an equation offering a good description of the viscosity–temperature relationship for ionic liquids. The equation makes used of fluidity that varies smoothly with temperature rather than sharply varying viscosity. This three-parameter fluidity has a clear physical foundation based on the dynamic crossover in the viscosity induced by temperature. It is applied to a series of normal aliphatic alcohols, methanol through n-dodecanol, proposing a good correlation for temperature dependence of the viscosity for the alcohols. Using the parameters of the equation, the dynamic crossover temperature (Tx) characteristic of glass forming liquid is calculated, which is found to be close to the values obtained by power law equation based on the mode coupling theory and the values reported from derivative analysis of the dielectric spectroscopy. The exponent of the fluidity equation is found to be universal for all studied alcohols (ϕ = 0.312), and then it is applied as a two-parameter equation. In addition, a universal behavior is found for the viscosity when the temperature is reduced by the crossover temperature for each alcohol. Finally, another recent proposed equation which correlates the surface tension and viscosity of a liquid is accurately applied for the alcohols.