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arXiv · 1009.1579

Shear banding and flow-concentration coupling in colloidal glasses

R. Besseling·L. Isa·P. Ballesta·G. Petekidis·M. E. Cates·W. C. K. Poon
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Abstract

We report experiments on hard sphere colloidal glasses that reveal a type of shear banding hitherto unobserved in soft glasses. We present a scenario that relates this to an instability arising from shear-concentration coupling, a mechanism previously thought unimportant in this class of materials. Below a characteristic shear rate $\dotγ_c$ we observe increasingly non-linear velocity profiles and strongly localized flows. We attribute this trend to very slight concentration gradients (likely to evade direct detection) arising in the unstable flow regime. A simple model accounts for both the observed increase of $\dotγ_c$ with concentration, and the fluctuations observed in the flow.

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R. Besseling, L. Isa, P. Ballesta, G. Petekidis, M. E. Cates, W. C. K. Poon. 2010-11-24. Shear banding and flow-concentration coupling in colloidal glasses. https://doi.org/10.1103/physrevlett.105.268301

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