Synthesis of Branched Polyethylene from Ethylene by Tandem Action of Iron and Zirconium Single Site Catalysts
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- 作者：Raú ; l Quijada ; René ; Rojas ; Guillermo Bazan ; Zachary J. A. Komon ; Raquel S. Mauler ; and Griselda B. Galland
- 刊名：Macromolecules
- 出版年：2001
- 出版时间：April 10, 2001
- 年：2001
- 卷：34
- 期：8
- 页码：2411 - 2417
- 全文大小：84K
- 年卷期：v.34,no.8(April 10, 2001)
- ISSN：1520-5835
文摘
The synthesis of low-density polyethylene from ethylene as the only monomer feed hasbeen investigated as an alternative route to branched polyethylene and to obtain new materials withdifferent properties, avoiding the need to feed 1-alkenes into the polymerization process. The details ofthe evaluation of two combination catalyst systems based on single site catalysts are discussed. The {[(2-ArN=C(Me))2C5H3N]FeCl2} (Ar = 2-C6H4(Et)) compound, designated as catalyst 1, oligomerizes ethyleneto produce linear 
-olefins with high selectivity, and Me2SiInd2ZrCl2 (2) or EtInd2ZrCl2 (3) are used ascatalysts that incorporate the -olefins in the polymer. For catalyst 1 in the presence of methylaluminoxane(MAO) and ethylene, a wide range of -olefin products were found, both soluble and insoluble. Also, tandemcatalyst combinations 1 and 2 or 1 and 3 in the presence of ethylene alone can readily produce branchedpolyethylene with levels of 1-4 branches per 100 units of ethylene. A change in activity was found forvariations in the Fe/Zr ratio for both systems, with lower activity but higher frequency of branching inthe polymer backbone for catalyst 2. The final product obtained by the 1/3/MAO systems, however, showsa more homogeneous structure as determined by DSC and GPC.
-olefins with high selectivity, and Me2SiInd2ZrCl2 (2) or EtInd2ZrCl2 (3) are used ascatalysts that incorporate the -olefins in the polymer. For catalyst 1 in the presence of methylaluminoxane(MAO) and ethylene, a wide range of -olefin products were found, both soluble and insoluble. Also, tandemcatalyst combinations 1 and 2 or 1 and 3 in the presence of ethylene alone can readily produce branchedpolyethylene with levels of 1-4 branches per 100 units of ethylene. A change in activity was found forvariations in the Fe/Zr ratio for both systems, with lower activity but higher frequency of branching inthe polymer backbone for catalyst 2. The final product obtained by the 1/3/MAO systems, however, showsa more homogeneous structure as determined by DSC and GPC.