Surfactant-induced flow compromises determination of air-water interfacial areas by surfactant miscible-displacement

Implications of surfactant-induced flow for miscible-displacement estimation of air-water interfacial areas in unsaturated porous media.

Surfactant miscible-displacement experiments represent a conventional means of estimating air-water interfacial area (A(I)) in unsaturated porous media. However, changes in surface tension during the experiment can potentially induce unsaturated flow, thereby altering interfacial areas and violating several fundamental method assumptions, including that of steady-state flow. In this work, the m...

Strongly Nonlinear Nature of Interfacial-surfactant Instability of Couette Flow

Nonlinear stages of the recently uncovered instability due to insoluble surfactant at the interface between two fluids are investigated for the case of a creeping plane Couette flow with one of the fluids a thin film and the other one a much thicker layer. Numerical simulation of strongly nonlinear longwave evolution equations which couple the film thickness and the surfactant concentration rev...

The interfacial structure of polymeric surfactant stabilised air-in-water foams.

Small-angle neutron scattering was used to probe the interfacial structure of nitrogen-in-water foams created using a series of tri-block polymeric surfactants of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (EOx-POy-EOx) range, from which the nature of the polymeric interface could be characterised. The data follow a pronounced Q(-4) decay, along with a number of inflexi...

Ultralow interfacial tensions in water– n -alkane–surfactant systems

Phase behavior and interfacial curvature in water-oil-surfactant systems

Even during 1995, 60 papers appeared using cosurfacrant in their formulations . If one does not have the choice of optimal surfacrants (there may be various commercial or scientific reasons), it may be helpful to use these add itives (e.g. in emulsion formulations, see below). Quantitative measurements of structures and their interpretation is facilitated, however, if one restricts oneself to t...