Dynamical light scattering study of abnormally fluid semi-dilute solutions of worm-like micelles

Light scattering experiments were carried out on aqueous micellar solutions of cetylpyridinium chlorate (CPClO3) in the presence of sodium chlorate (NaClO3) as a function of surfactant concentration. The time autocorrelation function of the scattered field is found to be bimodal. The slow relaxation time, that is assumed to be the terminal time of the stress relaxation, is a decreasing function of the surfactant concentration. The behaviour of the plateau modulus obtained by combining measurements of the slow relaxation time and of the zero-shear viscosity suggests the presence of entanglements in these highly fluid micellar systems.