Issue 18, 2011

From stress-induced fluidization processes to Herschel-Bulkley behaviour in simple yield stress fluids

Abstract

Stress-induced fluidization of a simple yield stress fluid, namely a carbopol microgel, is addressed through extensive rheological measurements coupled to simultaneous temporally and spatially resolved velocimetry. These combined measurements allow us to rule out any bulk fracture-like scenario during the fluidization process such as that suggested in [Caton et al., Rheol Acta, 2008, 47, 601–607]. On the contrary, we observe that the transient regime from solid-like to liquid-like behaviour under a constant shear stress σ successively involves creep deformation, total wall slip, and shear banding before a homogeneous steady state is reached. Interestingly, the total duration τf of this fluidization process scales as τf ∝ 1/(σσc)β, where σc stands for the yield stress of the microgel, and β is an exponent which only depends on the microgel properties and not on the gap width or on the boundary conditions. Together with recent experiments under imposed shear rate [Divoux et al., Phys. Rev. Lett., 2010, 104, 208301], this scaling law suggests a route to rationalize the phenomenological Herschel-Bulkley (HB) power-law classically used to describe the steady-state rheology of simple yield stress fluids. In particular, we show that the steady-state HB exponent appears as the ratio of the two fluidization exponents extracted separately from the transient fluidization processes respectively under controlled shear rate and under controlled shear stress.

Graphical abstract: From stress-induced fluidization processes to Herschel-Bulkley behaviour in simple yield stress fluids

Article information

Article type
Paper
Submitted
06 Apr 2011
Accepted
25 May 2011
First published
20 Jul 2011

Soft Matter, 2011,7, 8409-8418

From stress-induced fluidization processes to Herschel-Bulkley behaviour in simple yield stress fluids

T. Divoux, C. Barentin and S. Manneville, Soft Matter, 2011, 7, 8409 DOI: 10.1039/C1SM05607G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements