Shear Banding in a Micellar Solution under Transient Flow

We report on the results of rheological, optical, and small-angle light-scattering experiments performed on a solution of cetyltrimethylammonium bromide and sodium salicylate in water. The solution is subjected to a steplike shear rate and the response of the liquid is studied by recording the transient shear stress, the flow birefringence, and the scattered light intensity. This micellar system shows an enormous ``overshoot'' of the shear stress at the inception of the flow. A phase transition occurs during this process and the light is strongly scattered by the liquid. When the stationary state is reached, the flow shows the typical two-bands structure already observed in similar systems.