Shear driven vorticity aligned flocs in a suspension of attractive rigid rods
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d0sm01576h.pdf
Description
Published version
Size
10.68 MB
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Checksum (MD5)
33cb26bc28131a46f115af5de96aaa19
Author(s)
Das, Mohan
Chambon, Lucille
Varga, Zsigmond
Vamvakaki, Maria
Swan, James W
Petekidis, George
Date Issued
2021
Journal
Soft Matter
Publisher
Royal Society of Chemistry (RSC)
Version
Final published version
Abstract
A combination of rheology, optical microscopy and computer simulations was used to investigate the microstructural changes of a semi-dilute suspension of attractive rigid rods in an imposed shear flow. The aim is to understand the relation of the microstructure with the viscoelastic response, and the yielding and flow behaviour in different shear regimes of gels built from rodlike colloids. A semi-dilute suspension of micron sized, rodlike silica particles suspended in 11 M CsCl salt solution was used as a model system for attractive rods’ gel. Upon application of steady shear the gel microstructure rearranges in different states and exhibits flow instabilities depending on shear rate, attraction strength, volume fraction and geometrical confinement. At low rod volume fractions, the suspension forms large, vorticity aligned, particle rich flocs that roll in the flow-vorticity plane, an effect that is due to an interplay between hydrodynamic interactions and geometrical confinement as suggested by computer simulations. Experimental data allow the creation of a state diagram, as a function of volume fraction and shear rates, identifying regimes of stable (or unstable) floc formation and of homogeneous gel or broken clusters. The transition is related to dimensionless Mason number, defined as the ratio of shear forces to interparticle attractive force.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Terms of Use
Creative Commons Attribution 3.0 unported license
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DOI of Published Version
https://doi.org/10.1039/d0sm01576h
