Electric field induced structuring in clay-oil suspensions: new insights from WAXS, SEM, leak current, dielectric permittivity, and rheometry.

The electric field induced structuring in clay-oil suspensions has been studied by means of wide angle x-ray scattering (WAXS), rheometry, scanning electron microscopy (SEM), as well as leak current density and dielectric constant measurements. The clay particles' orientation distribution was inferred from the azimuthal changes of the clay diffraction peak intensity. The angular width of that distribution was quantified through an orientational order parameter. Chain and column formation processes were distinguished by comparison of the time evolution of the diffraction peak amplitude with that of the current density. Leak current density was measured for different electric field strengths E and clay particle concentrations Φ. The following scaling relation was found: [Formula: see text]. In addition, the dependence of the yield stress on the electric field and on the particle concentration was measured and shown to scale as: [Formula: see text].