The rheological behavior of micellar solutions of cationic surfactant, cetyl trimethyl ammonium bromide in the presence of a salt (KBr) and a co-surfactant (n-octanol) were analyzed. Shear viscosity and shear moduli were measured as a function of concentrations of the co-surfactant and additive. When these concentrations attained a certain critical threshold value, the micellar solution was found to exhibit a nonlinear viscoelastic behavior. It is due to the formation of supramolecular structures, which has been described by the Maxwell model of a viscoelastic fluid typical of worm-like micelles. The rheological behavior was also analyzed using Carreau and Carreau-Gahleitner models which were found to be in good agreement with the experimental results.

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