Abstract:Phase segregation and the evolution law of binary polymer system under the action of dynamic field were investigated by capillary rheometer. PE and PP with specific viscosity, meeting the requirements of phase-segregation, were chosen in our work. Multilayer sheets were successfully prepared by a single-screw extruder on the basis of "viscous encapsulation" phenomenon, which always caused the high viscosity fluid sandwiched by the low viscosity fluid. Gel permeation chromatography, polarized optical microscopy and finite element analysis software were used to study the structure and mechanism of stratified flow. The results reveal that, "core-shell" and PP-PE-PP "sandwich" structure can be obtained by controlling the rheological behavior of the material by control of the viscosity ratio of PE/PP, meanwhile, there exists aoptimized optimum processing window. Further more, it is found that the radial velocity of PP and PE is different, stratified flow attributes to material viscoelasticity and processing flow field.