The effects of the initial phase morphology and interfacial tension were investigated on the formation of gradient morphology in the polymer blends.For the same blends system

different initial phase morphology can be obtained by changing the rotating rate of the rotor during mixing. By means of scanning electron microscope(SEM)

the morphologies of the polymer blends before and after annealing were examined. Computer Image Analyzer was also applied to get the information about the radius and distribution of the dispersed phase.It was found that the initial diameter of the dispersed phase particles decreased with increasing the rotating rate of the rotor.After annealing for a certain time

the blend system with smaller initial dispersed particle size shows faster speed for the formation of gradient morphology.However

if the initial particle size is too small

it could be predicted that the formation of gradient morphology is difficult during a certain period of time.So it is expected that there is an optimum initial diameter for the formation of gradient morphology.The blend systems with different interfacial tension can be got through blending PP/EVAc、PE and EVAc with various VAc contents.It was found that all the blend systems could form gradient morphology under certain annealing conditions.The larger the interfacial tension in the blends

the faster the formation speed of gradient morphology.Interfacial tension as the driving force for dispersed phase droplet coarsing plays an important role in the formation of gradient morphology.