Oscillating Viscosity in a Lyotropic Lamellar Phase under Shear Flow

Anne-Sophie Wunenburger (1) , Annie Colin (1) , Jacques Leng (1) , Alain Arnéodo (1) , Didier Roux (1)

1 CRPP - Centre de recherches Paul Pascal

We report some time-dependent behavior of lyotropic lamellar phase under shear flow. At fixed stress, near a layering instability, the system presents an oscillating shear rate. We build up a new stress versus shear rate diagram that includes temporal behavior. This diagram is made of two distinct branches of stationary states which correspond, respectively, to disordered and ordered multilamellar vesicle phases. When increasing the shear stress, prior to the transition to the ordered structural state, sustained oscillations of the viscosity are recorded. They correspond to periodic structural change of the entire sample between a disordered and a ordered state of multilamellar vesicles.

Mots clés: rheochaos; non-linear rheology; lyotropic liquid crystal

Domaines: Matière Molle [cond-mat.soft]

Anne-Sophie Wunenburger, Annie Colin, Jacques Leng, Alain Arnéodo, Didier Roux. Oscillating Viscosity in a Lyotropic Lamellar Phase under Shear Flow. Physical Review Letters, 2001, 86, pp.1374. ⟨10.1103/PhysRevLett.86.1374⟩. ⟨hal-00097176⟩