Prediction of the viscoelastic properties of a cetyl pyridinium chloride/sodium salicylate micellar solution: (I) characterization

The characterization capability of constitutive equation on the viscoelastic property of micellar solution was checked in this study. A modified viscoelastic model was employed here to express the viscoelastic properties of a cetyl pyridinium chloride/sodium salicylate (CPyCl/NaSal) wormlike micellar solution at 22 degrees C that was experimentally obtained in 2010. The relaxation spectrum of the CPyCl/NaSal solution was fitted using the dynamic frequency sweep, the parameter in the Papanastasiou-Scriven-Macosko damping function was obtained using stress relaxation in step strain, the structuralized parameter f in the model was obtained using the steady shear stress, and the parameter zeta was obtained using the stress growth in the shear startup experiment. Afterwards, the first normal stress difference of the solution in the steady shear experiment was predicted. The study clearly shows improvement in the calculated viscoelastic properties of the micellar solution compared with those obtained by the Vasquez-Cook-Mckinley model, such as steady shear stress.