Structure and orientation dynamics of sepiolite fibers-poly(ethylene oxide) aqueous suspensions under extensional and shear flow, probed by in situ SAXS

The structure and orientation dynamics of sepiolite clay fibers about 1,000 nm long and 10 nm thick, suspended in an aqueous poly(ehtylene oxide) matrix of 10(5) g/mol molecular mass, have been studied under control extensional and shear flow. A new extensional flow cell developed at the Laboratoire de Rh,ologie and the combined rheology and small angle X-ray scattering (Rheo-SAXS) setup available at the European Synchrotron Radiation Facility have allowed access to in situ and time-resolved fiber orientations and structure properties in the volume of suspensions under flow. In the volume fractions and shear rate domains for which the suspensions exhibit shear-thinning properties, two regimes of orientation separated by a critical strain rate have been identified under extensional flow.