Viscoelastic behavior surfactant effects

Jimenez-Regalado E, Selb J, Candau F (2000) Effect of surfactant on the viscoelastic behavior of semidilute solutions of multisticker associating polyacrylamides. Langmuir 16 8611-8621... 

Imai, S.-i., Shikata, T. Viscoelastic behavior of surfactant threadlike micellar solutions effect of additives 3. J. Colloid Interface Sci. 2001, 244(2), 399-404. Olsson, U., Soderman, O., Guering, P. Characterization of micellar aggregates in viscoelastic surfactant solutions a nuclear magnetic resonance and hght scattering study. J. Phys. Chem. 1986, 90(21), 5223-5232. 

CMCs in the absence of added electrolyte may be greatly influenced by electrovis-cous effects marked decreases in intrinsic viscosity on electrolyte addition have been observed in many cases36). Peculiar and highly interesting rheological properties of surfactant solutions include observations of strongly non-Newtonian behavior as well as of viscoelasticity these are yet incompletely understood. 

The behavior of lyotropic crystals is usually non-Newtonian. Lamellar liquid crystals show thixotropic or negative thixotropic behavior,but shear thinning/thixotropy is more common. The shear thinning effect is ascribed to orientation of the liquid crystalline domains and some structural breakdown. Viscoelasticity has also been observed. If the concentration of the surfactant molecules is, however, low and close to the CMC, Newtonian flow will be observed. ... 

This is not to say that there are no unresolved issues in formulating the basic principals for a continuum description of fluid motions. Effective descriptions of the constitutive behavior of almost all complex, viscoelastic fluids are still an important fundamental research problem. The same is true of the boundary conditions at a fluid interface in the presence of surfactants, and effective methods to make the transition from a pure continuum description to one which takes account of the molecular character of the fluid in regions of very small scale is still largely an open problem. 

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