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Shear-Induced Defect Formation in a Nonionic Lamellar Phase

Medronho, Bruno LU ; Rodrigues, M.; Miguel, M. G.; Olsson, Ulf LU and Schmidt, C. (2010) In Langmuir 26(13). p.11304-11313
Abstract
H-2 NMR experiments on a nonionic oriented lamellar phase demonstrate that shear flow induces structural defects in the lamellar structure. These substantial structural changes give rise to a transition from a viscous to a solidlike behavior; the elastic modulus of presheared samples was found to increase, reversibly, with the applied preshear rate. A similar behavior was found when step-cycling the temperature toward the layer-to-multilamellar-vesicle transition and back at constant shear rate. However, while shear rate controls the defect density, the temperature is found to control the defect rigidity. The lamellar phase exhibits a shear-thinning behavior under steady shear conditions, following the power law eta similar to gamma(n),... (More)
H-2 NMR experiments on a nonionic oriented lamellar phase demonstrate that shear flow induces structural defects in the lamellar structure. These substantial structural changes give rise to a transition from a viscous to a solidlike behavior; the elastic modulus of presheared samples was found to increase, reversibly, with the applied preshear rate. A similar behavior was found when step-cycling the temperature toward the layer-to-multilamellar-vesicle transition and back at constant shear rate. However, while shear rate controls the defect density, the temperature is found to control the defect rigidity. The lamellar phase exhibits a shear-thinning behavior under steady shear conditions, following the power law eta similar to gamma(n), with n approximate to -0.4. Both the shear thinning and the elastic behavior are in agreement with the available theoretical models. The observed shear-induced structural defects are reversible and can be regarded as a pretransition prior to the shear-induced formation of multilamellar vesicles. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
26
issue
13
pages
11304 - 11313
publisher
The American Chemical Society
external identifiers
  • wos:000279239900122
  • scopus:77954292464
ISSN
0743-7463
DOI
10.1021/la100627z
language
English
LU publication?
yes
id
2980d920-5dad-4d69-bed0-cdfc0dbd8641 (old id 1629015)
date added to LUP
2010-07-22 11:46:54
date last changed
2018-05-29 11:22:48
@article{2980d920-5dad-4d69-bed0-cdfc0dbd8641,
  abstract     = {H-2 NMR experiments on a nonionic oriented lamellar phase demonstrate that shear flow induces structural defects in the lamellar structure. These substantial structural changes give rise to a transition from a viscous to a solidlike behavior; the elastic modulus of presheared samples was found to increase, reversibly, with the applied preshear rate. A similar behavior was found when step-cycling the temperature toward the layer-to-multilamellar-vesicle transition and back at constant shear rate. However, while shear rate controls the defect density, the temperature is found to control the defect rigidity. The lamellar phase exhibits a shear-thinning behavior under steady shear conditions, following the power law eta similar to gamma(n), with n approximate to -0.4. Both the shear thinning and the elastic behavior are in agreement with the available theoretical models. The observed shear-induced structural defects are reversible and can be regarded as a pretransition prior to the shear-induced formation of multilamellar vesicles.},
  author       = {Medronho, Bruno and Rodrigues, M. and Miguel, M. G. and Olsson, Ulf and Schmidt, C.},
  issn         = {0743-7463},
  language     = {eng},
  number       = {13},
  pages        = {11304--11313},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Shear-Induced Defect Formation in a Nonionic Lamellar Phase},
  url          = {http://dx.doi.org/10.1021/la100627z},
  volume       = {26},
  year         = {2010},
}