THE INFLUENCE OF PREPOLYMERIZATION WITH T I-MG SUPPORTED CATALYST ON THE GAS-PHASE POLYMERIZATION OF ETHYLENE AND THE MORPHOLOGY OF THE PE PARTICLES

The gas-phase polymerization of ethylene with prepolymerized Ti-Mg sup ported catalyst was studied, The results showed that catalytic activit y and hulk density of the product particles increased and the size dis tributions of the product particles narrowed with the using of prepoly merization method. The morphology of catalyst particles, prepolymer an d the polymerization product particles were studied by SEM and image a nalysis. From these investigation, it was found that the prepolymeriza tion makes catalyst particles pull with fissure. The particles oi prep olymer and polymerization product are composed of bound agglomerates o f fine secondary polymer globules, while the secondary polymer globule s consist of smaller primary particles, The average values of diameter s(DAV) of catalyst particles, prepolymer and the product particles by image analysis are 33 mu m, 168 mu m and 263 mu m, respectively, and t he ratios of the large axis to small axis (D/d) are 1.524, 1.540 and 1 .514, respectively.