|Rheological Features of Spherical Silica Suspensions
in Ethylene Glycol
-Rheology of Ideal Suspensions-
Department of Macromolecular Science, Osaka University, Osaka, Japan
Nippon Gomu Kyokaishi, (2004), 77(5), 166-172 General Review in Japanese.
Viscoelasticity is discussed for mono-disperse suspensions of spherical silica particles dispersed in ethylene glycol keeping hard-core inter-particle potential,so called ideal suspensions. The zero-shear viscosity and the high frequency limiting viscosity are functions only of the volume fraction of particles. The longest relaxation time is well described with time necessary for a particle to migrate by a distance equal to its own radius due to Brownian motion. Thus, the origin of viscoelasticity for the idel suspension is the Brownian motion of particles. Viscoelasticity of bimodal ideal suspensions with the hard-core inter-particle potential is also discussed. When a ratio of particle radii < 3,the shape of relaxation spectra is essentially the same as that of the mono-disperse ideal suspension. However, when the ratio > 5, the shape of the relaxation spectrum is much broader than that of the mono-disperse ideal suspension. Then,motion of two kinds of particles are likely averaged into that of a hypothetical particle with an average radius when the ratio < 3 in the bimodal ideal suspension.
Viscoelasticity, Ideal suspension, Relaxation time, Zero-shear viscosity, High frequency limiting viscosity