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- Title
Confined flows of a polymer microgel.
- Authors
Geraud, Baudouin; Bocquet, Lyderic; Barentin, Catherine
- Abstract
In this paper, we probe the influence of confinement on the flows of a polymer microgel, namely Carbopol. We compare its bulk rheological behavior, measured with a rheometer and well described by a Hershel-Bulkley law, to velocity profiles measured in rough microchannels, obtained with a particle tracking velocimetry technique. We show a strong disagreement between the bulk prediction for the velocity profiles and the measured ones in the microchannels. Velocity profiles in confined conditions are successfully analyzed within the framework of a non-local fluidity model introduced recently (J. Goyon et al. Nature, 454, 84 (2008)). This allows to determine a cooperativity length ξ, whose order of magnitude compares with the structure size of the microgel. Moreover, we measure flow curves using a rheometer for different gap conditions and also show that this set of data exhibit a strong effect of the confinement on the measured rheological properties. This is again characterized by a typical length of the same order as the cooperativity length scale ξ. We thus evidence confinement effects with two complementary experiments which both give the same typical length for the rearrangements in the flows. Graphical abstract:
- Subjects
CONFINED flow; MICROGELS; RHEOLOGY; PARTICLE tracking velocimetry; QUANTUM confinement effects
- Publication
European Physical Journal E -- Soft Matter, 2013, Vol 36, Issue 3, p1
- ISSN
1292-8941
- Publication type
Article
- DOI
10.1140/epje/i2013-13030-3