Stress and strain controlled rheometry on a concentrated lyotropic lamellar phase of AOT/Water/Iso-octane

Abstract

We present the results of extensive strain- and stress-controlled rheometry performed on an AOT-water-iso-octane system, which forms lamellar structures with a high density of topological defects. In spite of different time-scales, both measurement methods, strain- and stress-controlled, are shown to be controlled by the level of strain experienced by the material. In both cases, after a complex transition, an apparent steady state is reached. Whereas both apparent steady states are identical for intermediate shear rate and shear stress following a power law, these are found to differ once the lower values of applied shear rate and shear stress are considered. The origin of this difference i..