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Structure and rheology of the defect-gel states of pure and particle-dispersed lyotropic lamellar phases

Basappa, G and Suneel, * and Kumaran, V and Nott, PR and Ramaswamy, S and Naik, VM and Rout, D (1999) Structure and rheology of the defect-gel states of pure and particle-dispersed lyotropic lamellar phases. In: European Physical Journal B, 12 (2). pp. 269-276.


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We present important new results from light-microscopy and rheometry on a moderately concentrated lyotropic smectic, with and without particulate additives, Shear-treatment aligns the phase rapidly, except for a striking network of oily-streak defects, which anneals out much more slowly. If spherical particles several microns in diameter are dispersed in the lamellar medium, part of the defect network persists under shear-treatment, its nodes anchored on the particles. The sample as prepared has substantial storage and loss moduli, both of which decrease steadily under shear-treatment. Adding particles enhances the moduli and retards their decay under shear. The data for the frequency-dependent storage modulus after various durations of shear-treatment can be scaled to collapse onto a single curve. The elasticity and dissipation in these samples thus arises mainly from the defect network, not directly from the smectic elasticity and hydrodynamics.

Item Type: Journal Article
Publication: European Physical Journal B
Publisher: Springer Verlag
Additional Information: Copyright for this article belongs to Springer Verlag.
Keywords: non newtonian fluid flows;defects in liquid crystals;heterogeneous liquids;suspensions;dispersions;emulsions;pastes;slurries;foams;block copolymers
Department/Centre: Division of Mechanical Sciences > Chemical Engineering
Division of Physical & Mathematical Sciences > Physics
Date Deposited: 05 Jan 2005
Last Modified: 19 Sep 2010 04:15
URI: http://eprints.iisc.ac.in/id/eprint/1505

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