VISCOELASTIC PROPERTIES OF SUSPENSIONS WITH WEAKLY INTERACTING PARTICLES

Rheological characterization of a model suspension containing hydroxyl -terminated polybutadiene and glass beads with filler concentration up to 30% by volume was performed by using a Haake parallel disk rheomet er. The rheological tests conducted were the measurement of the storag e modulus, G', loss modulus, G '', and complex viscosity, eta, as fun ctions of the frequency and the steady shear viscosity as a function o f the shear rate. The linear viscoelastic region was determined to ext end up to 50% strain by measuring G', G '', and eta as functions of s train amplitude. By using multiple gap separations between the disks, it was found that the suspension did not exhibit slip at the walls of the rheometer. G' and G '' were used to determine the relaxation times distribution, G(i)(lambda(i), empty set) as functions of the relaxati on time, lambda(i), and the filler content, empty set. The relaxation moduli, G(i)(lambda(i), empty set), decreased with the relaxation time , but increased with the filler content. The Cox-Merz rule was also ob served to be valid for these suspensions. (C) 1998 John Wiley & Sons, Inc.