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Transient and Stead...
Transient and Steady-State Shear Banding in a Lamellar Phase as Studied by Rheo-NMR
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Medronho, Bruno (author)
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- Olsson, Ulf (author)
- Lund University,Lunds universitet,Fysikalisk kemi,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Physical Chemistry,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
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Schmidt, Claudia (author)
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Galvosas, Petrik (author)
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(creator_code:org_t)
- 2012-10-29
- 2012
- English.
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In: Zeitschrift für Physikalische Chemie. - : Walter de Gruyter GmbH. - 0942-9352 .- 2196-7156. ; 226:11-12, s. 1293-1313
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Abstract
Subject headings
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- Flow fields and shear-induced structures in the lamellar (L-alpha) phase of the system triethylene glycol mono n-decyl ether (C10E3)/water were investigated by NMR velocimetry, diffusometry, and H-2 NMR spectroscopy. The transformation from multilamellar vesicles (MLVs) to aligned planar lamellae is accompanied by a transient gradient shear banding. A high-shear-rate band of aligned lamellae forms next to the moving inner wall of the cylindrical Couette shear cell while a low-shear-rate band of the initial MLV structure remains close to the outer stationary wall. The band of layers grows at the expense of the band of MLVs until the transformation is completed. This process scales with the applied strain. Wall slip is a characteristic of the MLV state, while aligned layers show no deviation from Newtonian flow. The homogeneous nature of the opposite transformation from well aligned layers to MLVs via an intermediate structure resembling undulated multilamellar cylinders is confirmed. The strain dependence of this transformation appears to be independent of temperature. The shear diagram, which represents the shear-induced structures as a function of temperature and shear rate, contains a transition region between stable layers and stable MLVs. The steady-state structures in the transition region show a continuous change from layer-like at high temperature to MLV-like at lower temperature. These structures are homogeneous on a length scale above a few micrometers.
Subject headings
- NATURVETENSKAP -- Kemi -- Fysikalisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Physical Chemistry (hsv//eng)
Keyword
- Shear-Induced Structure
- Lamellar Phase
- NMR Velocimetry
- NMR
- Diffusometry
- H-2 NMR Spectroscopy
Publication and Content Type
- art (subject category)
- ref (subject category)
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