Rheological properties of lyotropic liquid crystals

Rheological studies of liquid crystalline systems based on sodium decylsulphate are reported. It was verified that for low shear rates, disk-like (N d ) micellar nematic mesophases show typical pseudo-plastic rheopectic behaviour, associated with a favourable orientation of anisometric micelles in t...

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Bibliographic Details
Published in:Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 1995-04, Vol.97 (2), p.151-156
Main Authors: Alcantara, Maria Regina, Vanin, JoséAtilio
Format: Article
Language:English
Subjects:
Chemistry
Colloidal state and disperse state
Exact sciences and technology
General and physical chemistry
Liquid crystals
Lyomesophases
Lyotropic liquid crystals
Micelles. Thin films
Rheology
Viscosity
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Summary:Rheological studies of liquid crystalline systems based on sodium decylsulphate are reported. It was verified that for low shear rates, disk-like (N d ) micellar nematic mesophases show typical pseudo-plastic rheopectic behaviour, associated with a favourable orientation of anisometric micelles in the flow field. The existence of a recovery time was observed, probably due to an orientational competition between flow effects and intermicellar interactions. The same sample observed at higher shear rates exhibited Newtonian behaviour, acting as a “dilute” system in which the interactions between the components are not sufficiently strong to prevent free diffusion. For rod-like (N c ) micellar nematic mesophases at low shear rates, rheopectic behaviour was observed. Additionally, a typical structural viscosity was detected, attributable to a superstructure break down arising from the shearing flow. For N c systems, the existence of a recovery time was observed only for low shear rate values, indicating that for higher values the flow completely orients the sample.
ISSN:0927-7757
1873-4359
DOI:10.1016/0927-7757(94)03078-E