Solution/air interfaces I. An oscillating jet relative method for determining dynamic surface tensions

A Novel Fast Technique for Measuring Dynamic Surface and Interfacial Tension of Surfactant Solutions at Constant Interfacial Area

“…The classical Wilhelmy plate and du Noüy ring methods have a broad time domain, but both meth-ods are too slow to measure the DST (DIT) during the first several seconds after formation of a fresh interface. The methods involving hydrodynamic flow, like the oscillating jet (9,10) and the inclined plate (11), are fast but have narrow time domains of measurements equal to 3 Ϫ50 ms and 0.05-2 s, respectively. Another disadvantage of the above two methods is they are applicable only at the solution/air interface.…”

Experimental and Computational Methods Pertaining to Surface Tension of Pharmaceuticals

“…By adjusting the osciallation frequency, the liquid vibrates to forms a jet having a series of stationary waves which depends chiefly on the characteristics of the orifice, its position, wave number, rate of flow and the surface tension of the liquid (Chang and Franses, 1995;Defay and Pétré, 1962;Stückrad et al, 1993;Thomas and Potter, 1975 …”

“…where γ is the surface tension on the wave surface (mN/m), f is the flow rate (m 3 /sec), ρ is the density of solution (kg/m3), λ is the wavelength of oscillation (m), r is the stream radius (m) , b/r is the wave amplitude, and Ψ differs from unity by about 1 part in 1000 (Thomas and Potter, 1975;Zhang and Zao, 1989). This method can be employed to measure surface tension versus surface age (dynamic surface tension) for surface age varying between 0.1 and 0.001 second of surfactant solutions and surface elastisity (Defay and Hommelen, 1958;Warszynski et al, 1998).…”

An optical technique for detecting minute-amplitude standing waves on a liquid jet

“…If we employ an orifice or nozzle whose outlet has an aspect ratio (maximum-to-minimum diameter ratio), A, only slightly exceeding unity so that the jet issuing from there bears waves having sufficiently small amplitudes, we encounter a technical problem: i.e., how to know where wave nodes and antinodes are located. For measuring the wavelengths only, an excellent technique is available which is still valid, to our own experience, for A lowered to ~ 1.02: the technique is to project the jet by an expanded beam of parallel light at right angles to the axis of the jet, thereby producing focal lines in a row on a screen placed behind the jet (Defay and P&r~ 1971; Thomas and Potter 1975). These lines are caused by the waves on the jet working as a series of lenses and hence they accurately corresponds to the axial locations of the nodes.…”