Langmuir, Vol.11, No.2, 669-673, 1995
Transient and Steady Flow of a Lamellar Liquid-Crystalline Surfactant Water-System
Transient and steady flow experiments were,carried out on liquid crystalline samples of poly(oxyethylene) alcohol/water systems, at different temperatures and concentrations within the lamellar phase region. From the experimental results we may deduce that the transient response is very complex, showing both a stress overshoot and an undershoot, depending on the cooperative effects of shear rate, surfactant concentration, and temperature. Moreover, the steady flow behavior depends dramatically on the shear history of the samples. These results have been related to the appearance of a mechanically induced structure, favored by the proximity to phase transition regions (cubic-lamellar phase and micellar-lamellar phase).