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Modified Heterogeneous Ziegler-Natta Catalysts for Preparation of Broad/Multi-Modal Molecular Weight Distribution Polyethylene

Author: WangHongLi
Tutor: HuangQiGu
School: Beijing University of Chemical Technology
Course: Materials Science and Engineering
Keywords: Internal electron donor Modified multiphase Ziegler-Natta catalysts Width / a multimodal molecular weight distribution Ethylene homopolymerization Ethylene / 1 - hexene copolymerization
CLC: TQ325.12
Type: Master's thesis
Year: 2010
Downloads: 66
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Abstract


Synthesized by three different structural phenoxy silanes electron donor (electron donor, ED) 4 - methylphenoxy trimethylsilyl , phenoxy trimethyl silane, 4 - chlorophenoxy trimethoxyphenyl silanes, used for the synthesis of supported Ziegler-Natta catalyst , the internal electron donor . The resulting inner electron donor , and as a third component in the synthesis of supported Ziegler-Natta catalyst process added, to obtain a series of modified heterophasic . Ziegler-Natta catalysts for the catalytic ethylene homopolymerization and ethylene with 1 - hexene copolymerization. Investigated the preparation conditions of the catalyst , comprising : TiCl4 dropwise addition, the temperature , the molar ratio of by TiCl4 and MgCl2, the molar ratio of the structure of ED , ED and of MgCl2 , ( CH3 ) 2CHOH influence on the catalyst and its ethylene polymerization with the molar ratio of MgCl2 ; studied the polymerization conditions, including: the polymerization temperature, polymerization time , the Al / Ti molar ratio of the copolymerizable monomer concentration on the polymerization behavior of vinyl . By 1H NMR, elemental analysis (EA) were characterized by the synthesis of phenoxy silane . Catalyst particle morphology and crystalline properties were characterized using SEM, X- ray powder diffraction . SEM , X - ray powder diffraction , DSC , TG , GPC, the polymer structure , particle morphology , crystallinity , melting point and the melting enthalpy , heat stability , molecular weight and molecular weight distribution (MWD) characterized by 13C NMR . The experimental results show that the catalyst for the homopolymerization of ethylene and copolymerization of ethylene and 1 - hexene are having a high activity . SEM results show that of the catalyst of the catalyst particles are spherical, the surface of the catalyst particles have a defect ; catalyst MgCl2 carrier the X - ray powder diffraction results showed that no significant crystallization peak , its crystalline properties was completely destroyed, the load of the beneficial TiCl4 . Polymer SEM results showed that the polymer particles were spherical ; GPC results show that the resultant polymer molecular weight distribution was wide / a multimodal molecular weight distribution ( MWD = 30-45 ) ; DSC and X. -ray powder diffraction results showed that the catalyst catalyzed ethylene / 1 - hexene copolymerization makes the crystallinity of the polymer decreased performance due to comonomer insertion ; 13C NMR results show that the resulting linear polyethylene homopolymer ; TG results show that the resultant polymer chains contain easily pyrolyzed The small molecule chain, the polymer thermal stability is good, and less ash .

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CLC: > Industrial Technology > Chemical Industry > Synthetic resins and plastics industry > Polymer resin and plastic > Polyolefin plastic > Polyethylene
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