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

G. Basappa, Suneel, V. Kumaran, P. R. Nott, S. Ramaswamy, V. M. Naik, D. Rout

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)269-276
Number of pages8
JournalEuropean Physical Journal B
Volume12
Issue number2
DOIs
Publication statusPublished - 2 Nov 1999

Keywords

  • 47.50.+d Non-Newtonian fluid flows
  • 61.30.Jf Defects in liquid crystals
  • 83.70.Hq Heterogeneous liquids: suspensions, dispersions, emulsions, pastes, slurries, foams, block copolymers, etc.

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