Collective rearrangement at the onset of flow of a polycrystalline   hexagonal columnar phase
  Creep experiments on polycrystalline surfactant hexagonal columnar phases show a power law regime, followed by a drastic fluidization before reaching a final stationary flow. The scaling of the fluidization time with the shear modulus of the sample and stress applied suggests that the onset of flow involves a bulk reorganization of the material. This is confirmed by X-ray scattering under stress coupled to \textit{in situ} rheology experiments, which show a collective reorientation of all crystallites at the onset of flow. The analogy with the fracture of heterogeneous materials is discussed. 
Teresa Bauer (LCVN), Julian Oberdisse (LCVN), Laurence Ramos (LCVN)