Effects Of Di-ether Compounds As External Donor On Propylene Polymerization Catalyzed By Supported Ziegler-Natta Catalysts

The thesis presents the study of effects of novel di-ethers as external dornor (ED) on the molecular weight distribution (MWD) and chain structure of polypropylene (PP) synthesized by supported Ziegler-Natta catalyst (DQ-1 type).Seven novel di-ethers (4 ethylene diaryl ehers and 3 trimethylene diaryl ethers) are synthesized by reactions between phenols and either 1,2-dibromoethane or 1,3-dibromopropane, using NaOH (50%) as the catalyst. Yields in the range of 70-80% were obtained in the reactions, and the raw product is easy to be purified.Ethylene diaryl ethers as ED in DQ-1/triethyl aluminium (TEA) catalyzed propylene polymerization showed little influences both on the activity and the stereospecificity of PP, but they change the chain structures of boiling n-heptane soluble PP. The amount of stereoblock structures were increased. The MWD of PP is also obviously changed by the ED, but in a complicated way. The influence lies on the electron donation ability of the ethers. The influence of ethylene di-p-tolyl ether (EDPT) is the greatest, and it strongly changed the active center distribution (ACD).Trimethylene diaryl ethers as ED showed a slight activation effect on the catalyst. The influences of trimethylene diaryl ethers on the MWD and ACD is weaker as compared with ethylene diaryl ethers. This species of ED have lower influence because of their abilitie of coordination are decreased.The prsent results show that the regulation of ACD as well as MWD in supported Ziegler-Natta catalyst is feasible by addition of the new type ED, through they have little effect on activity and stereospecificity. They also change the chain structure of the PP.