Issue |
Europhys. Lett.
Volume 36, Number 9, December III 1996
|
|
---|---|---|
Page(s) | 719 - 724 | |
Section | Condensed matter: electronic structure, electrical, magnetic and optical properties | |
DOI | https://doi.org/10.1209/epl/i1996-00293-9 | |
Published online | 01 September 2002 |
Observation of shear banding in worm-like micelles by NMR velocity imaging
Department of Physics, Massey University - Palmerston North, New Zealand
Received:
2
July
1996
Accepted:
8
November
1996
We report an observation of shear-banding, under Couette flow, of the worm-like
surfactant system cetyl pyridinium chloride/sodium salicylate (respective
concentrations of 100 mM and 60 mM in pure water). The method, based on
NMR velocity imaging, allows the direct measurement of velocity, and consequent
calculation of shear rate, at a spatial resolution of around ,
sufficient to resolve apparent slip at the inner wall from shear banding
within the bulk of the fluid. Above a critical shear rate (around
) a high shear rate band is observed in the annulus between
concentric rotating cylinders, the width of the band being of order
with a corresponding shear rate of order
. The precise
location of the band is sensitive to boundary conditions at the inner wall and
is shown to be susceptible to significant broadening.
PACS: 76.60.Pc – NMR imaging / 61.25.Hq – Macromolecular and polymer solutions; polymer melts / 47.27.Lx – Wall-bounded thin shear flows
© EDP Sciences, 1996
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