Deformation and Structural Re-formation of Lyotropic Cholesteric Liquid Crystal of Hydroxypropyl Cellulose + Water System

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Abstract
Flow properties and optical properties in applying and stopping shear on a lyotropic cholesteric liquid crystalline system of concentrated aqueous solutions of hydroxypropyl cellulose have been studied. The wave length dependence of transmitted light intensity through a sample subjected to steady shear have been measured quantitatively at various shear rates. The spectra of absorbance after the sudden cessation of steady shear flow are also observed as function of time. The shape of the spectrum at a steady state changes very much with shear rate. The shape of spectrum after the sudden cessation of steady shear always recovers quickly. A theoretical model including orientation distribution of Bragg reflection elements is proposed, which is useful to interpret observed spectra-data. Flow situations and also structural formation processes change markedly above and below a certain critical shear rate.