Abstract: The morphology evolution during melt blending plays an important role in the final microstructure and performance of multiphase polymeric materials. The dispersed phase size of immiscible polymer blends under flow is determined by the breakup and coalescence processes of droplets. The earlier studies are mainly limited to the Newtonian systems. Much of the deformation, breakup and coalescence theories of droplet have originated from the Newtonian fluid systems. In essence, polymer blends have many similarities with the Newtonian fluid. However, their unique viscoelastic properties play an important role that can not be neglectable during the morphological evolution. Recent experimental and theoretical progresses in the morphology of immiscible polymer blends with droplet structure under flow were summarized. Several theoretical models in predicting the dispersed phase size were compared. The influences of various factors such as shear rate, composition, elasticity, compatibilizer and filler on the morphology of dispersed phases were discussed.

Key words: polymer, blend, flow field, breakup, coalescence, immiscibility, disoersed phase, morphology