Structure Evolution of a Polymer Solution at High Shear Rates

Abstract

We utilized large angle light scattering to study the structure of a sheared semidilute polymer solution. Below a critical shear rate γ̇ c we observe an enhancement of concentration fluctuations in accordance with previous experimental and theoretical work. Above γ̇ c we find dramatic changes in the transient and steady state scattering behavior which indicate a shear-induced phase separation. A new four-peaked structure which coarsens in time is observed which is superimposed upon the scattering characteristic of low shear. The four-peaked scattering structure evolves into two peaks along the gradient direction, implying the formation of phase-separated domains elongated along the shear direction.