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Univ. Paris-Saclay
The yielding transition of soft colloids
L. Cipelletti - L2C University of Montpellier and CNRS, France
Vendredi 17/05/2019, 11:00-12:00
LLB - Bât 563 p15 (Grande Salle), CEA-Saclay

We investigate the yielding transition of dense suspensions of colloids interacting via a soft repulsive potential by simultaneously measuring their mechanical response and microscopic dynamics under an oscillating shear deformation. At low strain amplitude, the system exhibits ultraslow, ballistic dynamics characterized by a compressed exponential relaxation of correlators, similar to those reported for many jammed soft materials at rest.

Upon increasing the strain amplitude, the system undergoes a dynamic transition towards a steady state characterized by fast stretched exponential, diffusive-like relaxations. The dynamic transition coincides with the onset of the non-linear rheological response. While this scenario seems to be generic to soft colloids, the sharpness of the transition appears to depend on the potential details.

We present a simple model that accounts for this dynamic transition.

Contact : Alain MENELLE

 

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