Shear effects in a micellar solution near the critical point

This paper is concerned with theological properties of a phase-separating mixture in the presence of macroscopic shear flow. Specifically, we have investigated the shear viscosity of a nonionic micellar solution in shear-induced quasi-stl, tionary states, where a dynamical balance between the growing concentration domains and the suppression by shear is established. During the phase separation, when concentration domains of the two phases with viscosity difference are Ibrmed, the measured viscosity of all mixtures its a function of temperature is Ibtmd to satisfy to a good approximation a novel theological equation proposed by Onuki. In addition, we have determined that the observed characteristic temperatt.rc related to the crossover from the shear-affected regitne to the shear-unaflizcted regime depends on the shear rate its S v, with p = I +ʹz ~ [1.51, where v and z are universal critical exponents associated with the range and decay rate of the critical Iluctuations. This power law dependence on S, expected for a mixture at the critical composition, appears to be valid also Ior all off-critical mixtures.