Vanishing Elasticity for Wet Foams: Equivalence With Emulsions and Role of Polydispersity

Loading...
Thumbnail Image
Penn collection
Department of Physics Papers
Degree type
Discipline
Subject
foams
emulsions
yield stress
elasticity
elastic moduli
Physical Sciences and Mathematics
Physics
Funder
Grant number
License
Copyright date
Distributor
Related resources
Author
Saint-James, A.
Contributor
Abstract

We present an experimental study of the rheology of polydisperse aqueous foams of different gas volume fractions φ. With oscillatory deformation at fixed frequency, we determine the behavior of the maximum stress as a function of the strain amplitude. At low strain, the maximum stress increases linearly, defining a shear modulus G.G. At progressively higher strains, the response eventually becomes nonlinear, defining the yield strain and the yield stress. While φ decreases toward φc=0.635±0.01,φc=0.635±0.01, GG goes to zero, and the yield stress decreases by many orders of magnitude with a quadratic behavior. The yield strain, which can be extrapolated to 0.18±0.020.18±0.02 at φ=1,φ=1, has a minimum value of 0.045±0.0100.045±0.010 at φc.φc. This behavior shows the occurrence of a melting transition located at φc,φc, which can be correlated to the random close packing of spheres. We compare these results to similar ones obtained previously for monodisperse and polydisperse emulsions. Our new experiments clarify the rheological similarities between emulsions and foams, as well as the role of polydispersity. We find that as long as polydispersity is moderate, it does not play a crucial role in the elastic response of foams and emulsions.

Advisor
Date Range for Data Collection (Start Date)
Date Range for Data Collection (End Date)
Digital Object Identifier
Series name and number
Publication date
1999
Journal title
Journal of Rheology
Volume number
Issue number
Publisher
Publisher DOI
Journal Issue
Comments
At the time of publication, author Douglas J. Durian was affiliated with University of California Los Angeles. Currently, he is a faculty member at the Physics Department at the University of Pennsylvania.
Recommended citation
Collection