Viscoelastic and rheological behavior of concentrated colloidal suspensions
- Delft Univ. of Technology (Netherlands)
- Rockefeller Univ., New York, NY (United States)
Molecular approaches are discussed to the density ({phi}), viscoelastic ({omega}), and rheological ({gamma}) behavior of the viscosity {eta}({phi}, {omega}, {gamma}) of concentrated colloidal suspensions with 0.3 < {phi} < 0.6, where {phi} is the volume fraction, {omega} the applied frequency, and {gamma} the shear rate. These theories are based on the calculation of the pair distribution function P{sub 2}(r; {omega}, {gamma}), where r is the relative position of a pair of colloidal particles. The linear visoelastic behavior {eta}({phi}, {omega}, {gamma} = 0) follows from an equation for P{sub 2}(r, {omega}, {gamma}) derived from the Smoluchowski equation for small {phi}, generalized to large {phi} by introducing the spatial ordering and (cage) diffusion typical for concentrated suspensions. The rheological behavior {eta}({phi}, {omega} = 0, {gamma}) follows from an equation for P{sub 2}(r; {gamma}) of a dense hard-sphere fluid derived from the Liouville equation. This leads to a hard-sphere viscosity {eta}{sup hs}({phi}, {gamma}) which yields the colloidal one {eta}({phi}, {gamma}) by the scaling relation {eta}({phi}, {gamma})/{eta}{sub 0} = {eta}{sup hs}({phi}, {gamma})/{eta}{sub B}, where {eta}{sub 0} is the solvent viscosity, {eta}{sub B} is the dilute hard-sphere (Boltzmann) viscosity, and the {gamma}`s are appropriately scaled. {eta}({phi}, {omega}) and {eta}({phi}, {gamma}) agree well with experiment. A unified theory for {eta}({phi}, {omega}, {gamma}) is clearly needed and pursued.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG02-88ER13847
- OSTI ID:
- 50770
- Report Number(s):
- CONF-940633-; ISSN 0195-928X; TRN: 95:003581-0005
- Journal Information:
- International Journal of Thermophysics, Vol. 15, Issue 6; Conference: 12. symposium on thermophysical properties, Boulder, CO (United States), 19-24 Jun 1994; Other Information: PBD: Nov 1994
- Country of Publication:
- United States
- Language:
- English
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