Initial density dependence of experimental viscosities and of calculated diffusion coefficients of the binary vapor mixtures methanol-benzene and methanol-cyclohexane

The paper reports experimental results for the viscosity of the vapor mixtures methanol-benzene (five mole fractions with densities up to 1.5kg·m^–3 and 0.022 mol·L ^–1) and methanol-cyclohexane (four mole fractions with densities up to 1.9kg·m^–3 and 0.026 mol·L ^–1). In analogy to the pure components, the measurements on the mixtures were carried out with an oscillating-disk viscometer with small gaps, completely made of quartz, beginning as near as possible to room temperature and continuing to a maximum temperature of 630 K. A first evaluation by means of the Chapman-Enskog theory of dilute gases has shown differences in the resulting values of the interaction viscosity _ij ⁽⁰⁾ in the limit of zero density exceeding the experimental errors. Consistent results were obtained by taking into account the initial density dependence of the viscosity within the framework of the modified Enskog theory for gaseous mixtures. The values of _ij ⁽⁰⁾ were also used to estimate binary diffusion coefficients of the mixtures.