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Irreversible shear-activated aggregation in non-Brownian suspensions.
J Guery1, E Bertrand, C Rouzeau
1ESPCI, UMR 7612, Laboratoire Colloïdes et Matériaux Divisés, ParisTech, France.
Physical Review Letters
|June 29, 2006
Summary
Shear forces trigger irreversible aggregation in non-Brownian particle suspensions at low volume fractions. This phenomenon causes a sudden, dramatic increase in viscosity after a shear-rate-dependent induction time.
Area of Science:
- Rheology and soft matter physics.
- Colloid and surface science.
Background:
- Understanding particle suspension stability is crucial for various industrial applications.
- Non-Brownian particles exhibit unique behaviors distinct from Brownian motion.
Purpose of the Study:
- To investigate the impact of shear forces on the stability of non-Brownian particle suspensions.
- To identify and characterize shear-induced aggregation phenomena.
Main Methods:
- Experimental study of suspensions containing non-Brownian solid particles.
- Rheological measurements to monitor viscosity changes.
- Analysis of shear rate and induction time relationships.
Main Results:
- Demonstrated an irreversible aggregation transition at low volume fractions (phi ≈ 0.1).
- Observed a dramatic, sudden increase in viscosity post-aggregation.
- Found the induction time for aggregation is exponentially dependent on shear rate.
Conclusions:
- Hydrodynamic forces play a critical role in overcoming repulsive energy barriers, leading to aggregation.
- Shear-induced aggregation presents a significant rheological shift in non-Brownian suspensions.
- The findings offer insights into controlling particle interactions and suspension properties under flow.