Linear Viscoelasticity of Colloidal Hard Sphere Suspensions near the Glass Transition

The frequency-dependent viscoelastic shear modulus of concentrated suspensions of colloidal hard spheres is shown to be strongly modified as the volume fraction approaches the glass transition. The elastic or storage component, $G^{\prime }$, becomes larger than the viscous or loss component, $G^{\prime \prime }$. The frequency dependence of $G^{\prime }$ develops a plateau while that of $G^{\prime \prime }$ develops a minimum. We propose a physical model to account for these data, using a description of the glasslike behavior based on mode-coupling theory, and a description of the high-frequency behavior based on hydrodynamic flow calculations.