Exact solutions for the torsional interfacial viscometer with oscillatory motion are obtained. A sinusoidal oscillation is imposed upon the angular velocity of the dish. The bob is induced to oscillate with the same frequency as that of the dish. From measurements of the amplitude ratio and phase angle between these two oscillations, the surface shear viscosity can be determined. The analysis is confirmed by experimental measurement. The effects of various operational and instrumental variables upon the response of the bob are discussed. Typical behavior of the phase interface between the liquid-liquid adjoining phases is presented. The theoretical results suggest that the torsional interfacial viscometer with oscillatory motion is a viable instrument for measuring a wide spectrum of interfacial shear viscosity. The apparatus is schematically described. Experiments with the interface between air and an aqueous solution of sodium dodecyl sulfate and dodecyl alcohol are carried out and the results are analyzed by the developed theory.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Colloid and Surface Chemistry