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Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
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Microstructure of sheared monosized colloidal suspensions resulting from hydrodynamic and electrostatic interactions.
1Department of Chemical Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
The Journal of Chemical Physics
|June 2, 2014
Summary
This study details particle positions in sheared suspensions, revealing microstructure that explains shear-thickening behavior and the impact of electrostatic interactions on suspension rheology.
Area of Science:
- Fluid dynamics
- Colloid science
- Rheology
Background:
- Suspension microstructure dictates rheological behavior through hydrodynamic and near-particle interactions.
- Understanding these microstructural changes is key to predicting suspension properties.
Purpose of the Study:
- To characterize the microstructure of monosized silica particles in sheared suspensions.
- To elucidate the origins of shear-thickening at high shear rates.
- To investigate the role of electrostatic interactions in suspension behavior.
Main Methods:
- Obtaining individual particle positions in a microchannel flow with high detail.
- Calculating pair distribution functions and viscometric functions from the microstructure.
- Systematically varying ionic strength to screen electrostatic interactions.
Main Results:
- Pair distribution functions align with previous numerical studies at moderate to high Péclet numbers.
- Viscometric functions show qualitative agreement with computational results.
- Reduced ionic strength leads to a loss of anisotropy, consistent with soft particle systems.
Conclusions:
- Detailed microstructure analysis explains shear-thickening in suspensions.
- Hydrodynamic and electrostatic interactions significantly influence suspension anisotropy and rheology.
- The findings provide insights into the complex behavior of colloidal suspensions.
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