Related Experiment Videos
How are colloidal suspensions that age rejuvenated by strain application?
Virgile Viasnoff1, Stéphane Jurine, François Lequeux
1L.P.M UMR7615 CNRS ESPCI, 10 rue Vauquelin, 75231, Paris, France.
Faraday Discussions
|March 18, 2003
Summary
High shear rejuvenates colloidal suspensions, while moderate shear causes "overaging" by promoting aging. This study reveals how shear history impacts particle dynamics and relaxation times in dense suspensions.
Area of Science:
- Colloidal science
- Soft matter physics
- Rheology
Background:
- Dense colloidal suspensions exhibit complex dynamics under shear.
- Understanding particle relaxation and aging is crucial for predicting material behavior.
Purpose of the Study:
- To investigate the microscopic effects of shear on dense purely repulsive colloidal suspensions.
- To analyze the time evolution of relaxation time distributions after shear application.
Main Methods:
- Utilized multispeckle diffusing wave spectroscopy (MDWS).
- Monitored transient colloidal particle motions after oscillatory strain.
Main Results:
- High oscillatory shear rejuvenates the suspension, erasing sample history.
- Moderate shear leads to a non-trivial modification of relaxation times, termed 'overaging'.
- Overaging is understood by considering the complete relaxation time distribution.
Conclusions:
- Shear history significantly impacts colloidal suspension aging.
- The soft glassy rheology model can account for observed overaging phenomena.