VISCOSITY AND STRUCTURAL RELAXATION IN SUSPENSIONS OF HARD-SPHERE COLLOIDS

Viscometry and dynamic light scattering (DLS) were used to study suspensions of colloidal particles which interact Like hard spheres. The rate of ''structural relaxation'' of microscopic density fluctuations, indicated by the long-time diffusion coefficient measured by DLS at the peak of the static structure factor, was found to vary with particle concentration quantitatively like the inverse of the low-shear-rate viscosity. Sample concentrations were calibrated with respect to the thermodynamic ''freezing'' transition of the suspension.