Shear waves in viscoelastic wormlike micellar fluids over a broad concentration range
J R Gladden1, A M Gamble, C E Skelton
1Department of Physics and Astronomy, 108 Lewis Hall, University of Mississippi, University, Mississippi 38677, USA. jgladden@olemiss.edu
The Journal of the Acoustical Society of America
|March 20, 2012
Summary
Shear wave speeds in wormlike micellar fluids were measured, revealing concentration-dependent scalings. These viscoelastic fluids exhibit properties relevant for potential elastography applications.
Area of Science:
- Soft Matter Physics
- Rheology
- Materials Science
Background:
- Wormlike micellar (WM) fluids are complex fluids with viscoelastic properties.
- Understanding their mechanical behavior is crucial for various applications.
Purpose of the Study:
- To measure low-frequency shear wave speeds in CTAB/NaSAL wormlike micellar fluids.
- To investigate the relationship between shear wave speed and fluid concentration.
- To explore potential applications in elastography.
Main Methods:
- Shear wave speeds were measured at 61 Hz in WM fluids across a concentration range (20/12-500/300 mM CTAB/NaSAL).
- Birefringence and high-speed video with polarizing filters were used to track shear pulses.
- Rheology data provided elastic and loss moduli for comparison.
Main Results:
- Shear wave speed exhibited distinct concentration scalings: c(s) ~ √C at lower concentrations and c(s) ~ C at higher concentrations.
- A slope change was observed at 400 mM CTAB, with speeds ranging from 0.08-0.7 m/s.
- Equilibrium time significantly influenced shear wave speed, and propagation was dominated by the elastic modulus.
Conclusions:
- The study reveals fundamental relationships between concentration and shear wave propagation in WM fluids.
- The findings highlight the viscoelastic nature and potential utility of these fluids in elastography.
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