Rheological Properties of the L Phase and the Hexagonal, Lamellar, and Cubic Liquid Crystals of the CTAB/Benzyl Alcohol/Water System

Abstract

The rheological properties of different phases of the CTAB/benzyl alcohol/water system have been studied. The L phase, except the samples close to the hexagonal liquid crystal, is a viscous fluid with a characteristic Newtonian behavior. On the contrary, the L phase samples close to the hexagonal phase are pseudoplastic fluids built up of cylindrical micelles with elastic properties. The hexagonal liquid crystal behaves as a shear thinning fluid with a well-defined zero-shear-rate viscosity, while the lamellar liquid crystal does not show a zero-shear-rate viscosity and it presents yield stress values. Both liquid crystals have significant elastic properties although we could not find any linear region of viscoelasticity in the lamellar phase. The cubic liquid crystal is also an elastic phase with ringing gel properties. The hexagonal and cubic liquid crystals follow the Maxwell treatment only at low angular frequencies. Consequently, from the results the relaxation time and the instantaneous elastic modu...