Ti-Mg系载体催化剂预聚合对乙烯气相聚合及产物颗粒形态的影响

研究了Ti-Mg系载体催化剂经预聚合与未经预聚合的乙烯气相聚合反应。结果表明,预聚合使催化活性增大、产物堆密度增大、颗粒大小均匀。扫描电镜观察表明,预聚合使催化剂颗粒疏松、多缝隙。预聚物、聚合产物颗粒分别由细小的二级类球形粒子紧密聚集而成,二级粒子则由更细小的一级粒子组成。图象分析测得催化剂、预聚物、聚合产物颗粒平均粒径分别是33、168、263μm,长短轴之比(D/d)分别是1.524、1.540、1.514.

The Influence of Prepolymerization with Ti-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 supported catalyst was studied. The results showed that catalytic activity and bulk density of the prod uct particles increased and the size distributions of the product particles narrowed with the using of prepolymerization method. The morphology of catalyst particles, prepolymer and the polymerization product particles were studied by SEM and image analysis. From these investigation, it was found that the prepolymerization makes catalyst particles puff with fis sure. The particles of prepolymer and polymerization product are composed of bound ag glomerates of fine secondary polymer globules, while the secondary polymer globules consist of smaller primary particles. The average values of diameters (DAV) of catalyst particles,prepolymer and the product particles by image analysis are 33 um, 168 um and 263 um, re-spectively, and the ratios of the large axis to small axis(D/d) are 1. 524, 1. 540 and 1. 514,respectively.