The structure of colloidal suspensions under shear flow: Light scattering experiments

Abstract

The structure of a colloidal suspension under shear flow is investigated by light diffusion. The suspension, made of latex spheres (2a=750 Å) dispersed in a water and glycerol mixture, is in a liquid like state. We record the structure factor S(k) in the plane of shear for Peclet numbers (Pe=ya ²/D) lower than 10⁻¹. The structure factor presents an asymetrical deformation when increasing the shear rate: we observe both angular and amplitude shifts of the maximum of S(k); moreover, it depends on the side (compression side or dilatation side of S(k). These results are compared with a linear approximation and numerical results. This comparison shows that the relevant parameter is Pe*=Pe.r*, where r* is an effective radius derived from the interparticle potential.