RHEOLOGICAL PROPERTIES OF THE L-PHASE AND THE HEXAGONAL, LAMELLAR, AND CUBIC LIQUID-CRYSTALS OF THE CTAB BENZYL ALCOHOL/WATER SYSTEM/

The rheological properties of different phases of the CTAB/benzyl alco hol/water system have been studied. The L phase, except the samples cl ose to the hexagonal liquid crystal, is a viscous fluid with a charact eristic Newtonian behavior. On the contrary, the L phase samples close to the hexagonal phase are pseudoplastic fluids built up of cylindric al micelles with elastic properties. The hexagonal liquid crystal beha ves as a shear thinning fluid with a well-defined zero-shear-rate visc osity, while the lamellar liquid crystal does not show a zero-shear-ra te viscosity and it presents yield stress values. Both liquid crystals have significant elastic properties although we could not find any li near region of viscoelasticity in the lamellar phase. The cubic liquid crystal is also an elastic phase with ringing gel properties. The hex agonal and cubic liquid crystals follow the Maxwell treatment only at low angular frequencies. Consequently, from the results the relaxation time and the instantaneous elastic modulus have been obtained. The re laxation times range in these phases from 2 to 9 s while the relaxatio n times of the cylindrical micelles are three decades smaller.