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Journal Articles Soft Matter Year : 2009

Shear-induced fragmentation of Laponite suspensions

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Abstract

Simultaneous rheological and velocity profile measurements are performed in a smooth Couette geometry on Laponite suspensions seeded with glass microspheres and undergoing the shear-induced solid-to-fluid (or yielding) transition. Under these slippery boundary conditions, a rich temporal behaviour is uncovered, in which shear localization is observed at short times, that rapidly gives way to a highly heterogeneous flow characterized by intermittent switching from plug-like flow to linear velocity profiles. Such a temporal behaviour is linked to the fragmentation of the initially solid sample into blocks separated by fluidized regions. These solid pieces get progressively eroded over time scales ranging from a few minutes to several hours depending on the applied shear rate $\dot{\gamma}$. The steady-state is characterized by a homogeneous flow with almost negligible wall slip. The characteristic time scale for erosion is shown to diverge below some critical shear rate $\dot{\gamma}^\star$ and to scale as $(\dot{\gamma}-\dot{\gamma}^\star)^{-n}$ with $n\simeq 2$ above $\dot{\gamma}^\star$. A tentative model for erosion is discussed together with open questions raised by the present results.
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Dates and versions

ensl-00371654 , version 1 (30-03-2009)

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Thomas Gibaud, Catherine Barentin, Nicolas Taberlet, Sébastien Manneville. Shear-induced fragmentation of Laponite suspensions. Soft Matter, 2009, 5 (1), pp.3026-3037. ⟨10.1039/b906274b⟩. ⟨ensl-00371654⟩
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