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Issue 25, 2013
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Yield stress, thixotropy and shear banding in a dilute aqueous suspension of few layer graphene oxide platelets

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Abstract

We demonstrate a rigidity percolation transition and the onset of yield stress in a dilute aqueous dispersion of graphene oxide platelets (aspect ratio ∼5000) above a critical volume fraction of 3.75 × 10−4 with a percolation exponent of 2.4 ± 0.1. The viscoelastic moduli of the gel at rest measured as a function of time indicate the absence of structural evolution of the 3D percolated network of disks. However a shear-induced aging giving rise to a compact jammed state and shear rejuvenation indicating a homogenous flow is observed when a steady shear stress (σ) is imposed in creep experiments. We construct a shear diagram (σ vs. volume fraction ϕ) and the critical stress above which shear rejuvenation occurs is identified as the yield stress σy of the gel. The minimum steady state shear rate [small gamma, Greek, dot above]m obtained from creep experiments agrees well with the end of the plateau region in a controlled shear rate flow curve, indicating a shear localization below [small gamma, Greek, dot above]m. A steady state shear banding in the plateau region of the flow curve observed in particle velocimetry measurements in a Couette geometry confirms that the dilute suspensions of GO platelets form a thixotropic yield stress fluid.

Graphical abstract: Yield stress, thixotropy and shear banding in a dilute aqueous suspension of few layer graphene oxide platelets

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Supplementary files

Article information


Submitted
12 Mar 2013
Accepted
15 Apr 2013
First published
15 May 2013

Soft Matter, 2013,9, 5874-5882
Article type
Paper

Yield stress, thixotropy and shear banding in a dilute aqueous suspension of few layer graphene oxide platelets

K. S. Vasu, R. Krishnaswamy, S. Sampath and A. K. Sood, Soft Matter, 2013, 9, 5874
DOI: 10.1039/C3SM50708D

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