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Viscoelasticity of a nonionic lamellar phase

Medronho, Bruno LU ; Miguel, Maria LU and Olsson, Ulf LU (2007) In Langmuir 23(10). p.5270-5274
Abstract
The linear viscoelastic properties of a nonionic lamellar phase in C-orientation were studied as a function of temperature by small-amplitude oscillatory measurements in the frequency range 0.5-5 Hz. An almost solidlike elastic response was observed at all studied temperatures, from 42 to 20 degrees C. In this range, the elastic modulus was found to increase strongly with decreasing temperature. The elasticity is attributed to screw dislocations connecting layers in the stack, and the data thus suggest that the density of screw dislocations decreases with increasing temperature. The lamellar phase forms an "onion" texture when continuously sheared at lower temperatures. It is argued that a possible origin for the shear-induced "onion"... (More)
The linear viscoelastic properties of a nonionic lamellar phase in C-orientation were studied as a function of temperature by small-amplitude oscillatory measurements in the frequency range 0.5-5 Hz. An almost solidlike elastic response was observed at all studied temperatures, from 42 to 20 degrees C. In this range, the elastic modulus was found to increase strongly with decreasing temperature. The elasticity is attributed to screw dislocations connecting layers in the stack, and the data thus suggest that the density of screw dislocations decreases with increasing temperature. The lamellar phase forms an "onion" texture when continuously sheared at lower temperatures. It is argued that a possible origin for the shear-induced "onion" texture is the instability of the screw dislocations in shear flow. By H-2 NMR experimentation, we also find the formation of a random mesh phase at lower temperatures. The presence of equilibrium bilayer perforations, however, does not correlate with the "onion" stability. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
23
issue
10
pages
5270 - 5274
publisher
The American Chemical Society
external identifiers
  • wos:000246071800011
  • scopus:34249734160
ISSN
0743-7463
DOI
10.1021/la063599a
language
English
LU publication?
yes
id
0bb46c55-399c-4dba-9f58-3b84a137b734 (old id 662990)
date added to LUP
2007-12-15 14:35:52
date last changed
2017-08-06 03:47:11
@article{0bb46c55-399c-4dba-9f58-3b84a137b734,
  abstract     = {The linear viscoelastic properties of a nonionic lamellar phase in C-orientation were studied as a function of temperature by small-amplitude oscillatory measurements in the frequency range 0.5-5 Hz. An almost solidlike elastic response was observed at all studied temperatures, from 42 to 20 degrees C. In this range, the elastic modulus was found to increase strongly with decreasing temperature. The elasticity is attributed to screw dislocations connecting layers in the stack, and the data thus suggest that the density of screw dislocations decreases with increasing temperature. The lamellar phase forms an "onion" texture when continuously sheared at lower temperatures. It is argued that a possible origin for the shear-induced "onion" texture is the instability of the screw dislocations in shear flow. By H-2 NMR experimentation, we also find the formation of a random mesh phase at lower temperatures. The presence of equilibrium bilayer perforations, however, does not correlate with the "onion" stability.},
  author       = {Medronho, Bruno and Miguel, Maria and Olsson, Ulf},
  issn         = {0743-7463},
  language     = {eng},
  number       = {10},
  pages        = {5270--5274},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Viscoelasticity of a nonionic lamellar phase},
  url          = {http://dx.doi.org/10.1021/la063599a},
  volume       = {23},
  year         = {2007},
}