Effect of the interfacial viscosities upon displacement



A capillary rise technique was developed for measuring the effect of the surface viscosities upon the displacement of air by liquids in glass capillaries. Measurements were made in two tubes with optically measured radii of 37.5 and 48.6 μm.

No surface viscous effects were observed with doubly distilled water or with octane, in good agreement with the Washburn equation. The behavior of a dilute aqueous solution of dodecyl sodium sulfate was easily distinguished from that corresponding to zero surface viscosities. The surface dilatational viscosity was found to be two orders of magnitude greater than the surface shear viscosity. Previous qualitative (Slattery, 1974, 1979) and quantitative (Giordano and Slattery, 1983) theories for the effect of the interfacial viscosities upon displacement are fully supported by this experimental study.