Surface tension of flowing soap films J. Fluid Mech. 841, R2 (2018) PDF

by Sane, Mandre and Kim

Feb 20, 2018 Fluid Mechanics Surfactants

Abstract:

The surface tension of flowing soap films is measured with respect to the film thickness and the concentration of soap solution. We perform this measurement by measuring the curvature of the nylon wires that bound the soap film channel and use the measured curvature to parametrize the relation between the surface tension and the tension of the wire. We find that the surface tension of our soap films increases when the film is relatively thin or is made of soap solution of low concentration; otherwise, it approaches an asymptotic value of 30 mN/m. A simple adsorption model with only two parameters describes our observations reasonably well. With our measurements, we are also able to estimate the Gibbs elasticity of our soap film.