BIMODAL MODEL OF SUSPENSION VISCOELASTICITY

In the bimodal model of the viscoelastic behavior of a bimodal suspens ion with a colloidal size fine fraction and a noncolloidal size coarse fraction, the two fractions behave independently of each other when t he particle size ratio is large: The colloidal fraction is solely resp onsible for the non-Newtonian behavior while only hydrodynamic interac tion takes place between the coarse particles. Measurements performed on a bimodal suspension and on a suspension of noncolloidal particles in a polymeric liquid indicate that the non-Newtonian behavior origina tes from the colloidal fraction in the former and from the polymeric l iquid in the latter. The results support the validity of the concepts behind the bimodal model. (C) 1997 The Society of Rheology.