Aggregates relaxation in a jamming colloidal suspension after shear cessation

TL;DR

This study investigates how reversible particle aggregates form and relax in a shear-thickening colloidal suspension using dynamic light scattering, revealing that higher shear stress prolongs aggregate relaxation times.

Contribution

It introduces speckle visibility spectroscopy to monitor aggregate formation and relaxation in colloids, highlighting the stress-dependent dynamics in the jamming regime.

Findings

Aggregate relaxation time increases with applied shear stress

Aggregation involves increased size and packing density

Relaxation dynamics depend on shear stress magnitude

Abstract

The reversible aggregates formation in a shear thickening, concentrated colloidal suspension is investigated through speckle visibility spectroscopy, a dynamic light scattering technique recently introduced [P.K. Dixon and D.J. Durian, Phys. Rev. Lett. 90, 184302 (2003)]. Formation of particles aggregates is observed in the jamming regime, and their relaxation after shear cessation is monitored as a function of the applied shear stress. The aggregates relaxation time increases when a larger stress is applied. Several phenomena have been proposed to interpret this behavior: an increase of the aggregates size and volume fraction, or a closer packing of the particles in the aggregates.