We report on the nonlinear shear rheology of wormlike micelles made of cetylpyridinium chloride (CP+,Cl-) and sodium salicylate (Na+,Sal(-)) diluted in 0.5 M NaCl-brine. A unique solution at concentration phi = 12 has been investigated (T = 20.3 degrees C). This strongly viscoelastic surfactant solution is an almost perfect Maxwellian fluid in the low-frequency range (omega (gamma) over dot I/N, the system undergoes the transition toward a strongly inhomogeneous flow, which can be ascribed to the isotropic/nematic shear-induced transition. The present findings suggest finally that, in wormlike micellar solution, the purely mechanical instability does exist but is preempted by the transition toward an (nematic) inhomogeneous now. References: 27
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