Viscoelastic properties of sterically stabilized nonaqueous dispersions

The viscoelastic properties of a dispersion of poly(vinyl acetate) particles sterically stabilized by poly(2-ethyl hexyl methacrylate) and dispersed in Isopar G have been measured as a function of particle concentration and frequency at ambient temperature.At low particle concentrations, it was found that the loss modulus was larger than the storage modulus, while at high particle concentrations, i.e.,w>0.40, the storage modulus was found to be larger than the loss modulus. This inversion from a viscous to an elastic response as a function of particle concentration is attributable to the change in the configurational entropy of the steric barrier as a result of increasing the concentration of particles in the dispersion.