Vorticity banding during the lamellar-to-onion transition in a lyotropic surfactant solution in shear flow

Vorticity banding during the lamellar-to-onion transition in a lyotropic surfactant solution in shear flow

We report on the rheology of a lyotropic lamellar surfactant solution (SDS/dodecane/pentanol/ water), and identify a discontinuous transition between two shear thinning regimes which correspond to the low-stress lamellar phase and the more viscous shear-induced multilamellar vesicle, or "onion&...

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Bibliographic Details
Published in:The European physical journal. E, Soft matter and biological physics Vol. 21; no. 2; pp. 133 - 143
Main Authors: WILKINS, G. M. H, OLMSTED, P. D
Format: Journal Article
Language:English
Published: Heidelberg Springer 01-10-2006
Subjects:
Alkanes - chemistry
Chemistry
Exact sciences and technology
General and physical chemistry
Pentanols - chemistry
Phase Transition
Rheology
Shear Strength
Sodium Dodecyl Sulfate - chemistry
Solution properties
Solutions
Stress, Mechanical
Surface physical chemistry
Surface-Active Agents - chemistry
Surface-active agents: properties
Viscosity
Water - chemistry
Water
Dodecane
Hydrocarbon
Shear flow
Alcohol
Surfactant
Pentanols
Phase transitions
Lauryl sulfate
Sodium Compounds
Anionic surfactant
Lamellar structure
Alkane
Alkanol
Lyotropic state
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Summary:We report on the rheology of a lyotropic lamellar surfactant solution (SDS/dodecane/pentanol/ water), and identify a discontinuous transition between two shear thinning regimes which correspond to the low-stress lamellar phase and the more viscous shear-induced multilamellar vesicle, or "onion" phase. We study in detail the flow curve, stress as a function of shear rate, during the transition region, and present evidence that the region consists of a shear-banded phase where the material has macroscopically separated into bands of lamellae and onions stacked in the vorticity direction. We infer very slow and irregular transformations from lamellae to onions as the stress is increased through the two-phase region, and identify distinct events consistent with the nucleation of small fractions of onions that coexist with sheared lamellae.
ISSN:1292-8941
1292-895X
DOI:10.1140/epje/i2006-10053-9