The High-Frequency Shear Modulus of Colloidal Suspensions and the Effects of Hydrodynamic Interactions

✍ Scribed by Norman J. Wagner

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 632 KB
• Volume: 161
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1993.1456

✦ Synopsis

The high-frequency shear modulus of a monodisperse colloidal suspension is derived from both linear response theory and a zero-time correlation function. The results are shown to reduce to the classical expression valid for molecular fluids in the limit of no hydrodynamic interaction. The expressions with an additional pairwise additive stress approximation agree with previous work on dense suspensions, thus clarifying the approximations in previous derivations. A phenomenological model based on a lattice structure is also recovered through suitable approximation for the neighbor distribution and neglect of hydrodynamic interactions. Sample calculations for a suspension of charged, Brownian spheres demonstrate that the intercolloidal parameters obtained from fitting the lattice model are not in agreement with the calculation here. Further, predictions of this theory, without adjustable parameters, are in good agreement with wave-rigidity measurements on suspensions of charged, polystyrene spheres. The role and influence of hydrodynamic interactions are discussed and the validity of the pairwise additive assumption is also tested. (1993 Academic Press. Inc.