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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 2: Polymer Physics I
CPP 2.7: Vortrag
Montag, 26. März 2007, 11:45–12:00, H40
Collective rearrangement under shear of a polycrystalline soft material — •Teresa Bauer1,2, Julian Oberdisse1, and Laurence Ramos1 — 1Laboratoire des Colloïdes, Verres et Nanomatériaux (UMR CNRS-UM2 5587), CC26, Université Montpellier 2, France — 2Lehrstuhl für Biophysik E22, Technische Universität München, Germany
Polycrystalline soft materials show interesting rheological behaviour in creep experiments. Initially the instantaneous shear rate decreases as a power law with time in a similar manner as a solid. This power law regime is followed by an abrupt increase of the shear rate, indicating a fluidization of the sample, and finally reaches a stationary flow with a high constant shear rate. Here we studied how this behaviour is coupled to a structural rearrangement of the sample by conducting in situ rheology and Synchrotron (ID2 ESRF) SAXS measurements on a polycrystalline surfactant hexagonal columnar phase simultaneously. We show that a collective reorientation of the crystallites occurs at the onset of flow. We discuss how the fluidization time, which scales with the shear modulus and the applied stress, is related to structural changes.