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.
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Received 19 April 1999 and Received in final form 20 May 1999
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Basappa, G., , S., Kumaran, V. et al. Structure and rheology of the defect-gel states of pure and particle-dispersed lyotropic lamellar phases. Eur. Phys. J. B 12, 269–276 (1999). https://doi.org/10.1007/s100510051004
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DOI: https://doi.org/10.1007/s100510051004