Dynamics of the phase behavior of a polymer blend under shear flow

We study the dynamics of the phase behavior of a polymer blend in the prese nce of shear flow. By adopting a two-fluid picture and using a generalizati on of the concept of material derivative, we construct kinetic equations th at describe the phase behavior of polymer blends in the presence of externa l flow. A phenomenological form for the shear modulus for the blend is prop osed. The study indicates that a nonlinear dependence of the shear modulus of the blend on the volume fraction of one of the species is crucial for a shift in the stability line to be induced by shear flow. [S1063-651X(99)125 01-7].