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Li H.,Beijing Lihe Technology Ltd. | Li S.,Beijing Lihe Technology Ltd. | Zhang J.,Beijing Lihe Technology Ltd.
Hecheng Shuzhi Ji Suliao/China Synthetic Resin and Plastics | Year: 2014

The authors summarized the research progress of internal electron donors(IDs) in Ziegler- Natta(Z-N) catalysts for propylene polymerization and evaluated the applications of the catalysts with different IDs. The Z-N catalysts with 1, 3-diethers, succinates and 1, 3-diol diesters compounds as IDs have high activity and stereospecificity. The resultant polypropylene has characteristic relative molecular mass distribution. Moreover, it is found by analyzing the active center models of the catalysts prepared with representative IDs that the isotactic and atactic active centers in monoester system under the influence of Lewis acid exist dynamic equilibrium, and the performance of Ti active centers in diether catalyst system is affected by the transfer of electron cloud from oxygen atoms of diether to Ti active centers and the spatial structure of diether. Source


Li H.,Beijing Lihe Technology Ltd. | Zhang J.,Beijing Lihe Technology Ltd. | Wang Z.,Beijing Lihe Technology Ltd. | Li S.,Beijing Lihe Technology Ltd.
Hecheng Shuzhi Ji Suliao/China Synthetic Resin and Plastics | Year: 2015

A series of 9-alkoxymethyl-fluorencarbonsaeure-(9)-esters were synthesized, characterized with hydrogen nuclear magnetic resonance (H-NMR) and used as internal donors for the preparation of Ziegler-Natta catalysts. These catalysts were evaluated for propylene polymerization and showed high catalytic activity, and the resultant polypropylene had high isotacticity. The catalytic performance could be adjusted by adopting different external donors in propylene polymerization in order to further improve the comprehensive properties of the catalysts, and consequently the polypropylene isotacticity could be increased without sacrifice of much activity. These catalyst showed equivalent or even higher activity and better stereospecificity compared to catalysts with dibutyl phthalate, 9,9-bis (methoxymethyl) fluorene and 2,3-diisopropyl succinate as internal donors respectively under the same catalyst preparation process and polymerization condition. ©, 2015, Research Institute of Beijing. All right reserved. Source

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