VISCOELASTIC BEHAVIOR OF AN ORDERING LATEX SUSPENSION IN A STEADY SHEAR-FLOW

The linear viscoelastic behavior of an ordering polystyrene latex duri ng steady shear how has been investigated. In this study a home-made i nstrument has been used that superimposes a small-amplitude oscillator y shear orthogonal onto the steady shear how. The measurements can be interpreted as due to the coexistence of two phases under flow. For in creasing shear rate the ordered (or solidlike) phase melts away until the suspension becomes completely disordered (or fluidlike). A model i s presented in which the fluid is conceived as a viscoelastic matrix c ontaining spherical viscoelastic domains. The model predicts a similar linear viscoelastic behavior of sheared lattices as found experimenta lly. The resulting parameters give information about the microstructur e of the dispersion under shear flow.