Study on homogeneous polymerization of 1-hexene with zirconocene/methylaluminoxane catalysis and synthesis of oscillating zirconocene catalysts.
Item
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Title
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Study on homogeneous polymerization of 1-hexene with zirconocene/methylaluminoxane catalysis and synthesis of oscillating zirconocene catalysts.
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Identifier
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AAI9732991
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identifier
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9732991
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Creator
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Zhao, Xia.
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Contributor
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Adviser: George Odian
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Date
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1997
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Polymer | Chemistry, Organic
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Abstract
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Part A: Homogeneous Polymerization of 1-Hexene with Zirconocene/MAO catalysis. The kinetics of 1-hexene polymerization initiated by rac-dimethylsilyl bis (4,5,6,7-tetrahydro-1-indenyl) zirconium dichloride/methyaluminoxane (MAO) catalysis was investigated. Polymerization rate was proportional to (Zr) (MAO) {dollar}\sp{lcub}1-2{rcub}{dollar} (M) {dollar}\sp{lcub}1-2{rcub}{dollar}. The fractional orders to which polymerization rate depends on monomer and MAO concentrations changed with temperature. Polymerization rate constant k{dollar}\sb{lcub}\rm p{rcub}{dollar} and activation energy E{dollar}\sb{lcub}\rm p{rcub}{dollar} were determined. Three types of unsaturated end groups were studied. The relationships between chain transfer rates to form these three types of end groups and zirconocene concentration, MAO concentration and monomer concentration were determined. Chain transfer to the coordinated monomer was predominating. At low temperature, catalyst species participated chain transfer reactions. The MAO effect on chain transfer was complicated as that in propagation. Kinetic model of polymerization and chain transfers was proposed based on the kinetic results. The results of polymer molecular weight support the kinetic results.;Isotacticity was investigated on both %mmmm and %mmmmmm levels. Isotacticity decreased tremendously with the increase of temperature. With the increase of monomer concentration, isotacticity increased and then leveled off. Isotacticity decreased with the increase of zirconocene concentration and MAO concentration. Regioregularity was only slightly affected by reaction conditions.;Part B: Synthesis of Oscillating Zirconocene catalysts. Bis (2-phenyl indenyl) zirconium dichloride (Cat.l), bis (1,2-diphenyl) zirconium dichloride (Cat.2), bis (2-methyl-1-phenyl) zirconium dichloride (Cat.3), (2-phenylindenyl) (1,2,3-triphenylindenyl) zirconium dichloride (Cat.4) and bis (1,2-dimethylindenyl) zirconium dichloride (Cat.5) were synthesized as oscillating metallocene catalysts and were characterized. The polymerization of 1-hexene with the catalysis of the above catalysts was performed at different temperatures, respectively. The isotacticity of polymers was investigated by {dollar}\sp{13}{dollar}C NMR at both pentad and heptad levels. Cat.1 could only produce atactic polymer at higher temperature and stereoblock polymer with small to medium amount of isotactic sequences at 20 and 0{dollar}\sp\circ{dollar}C. Cat.2 could produce polymer with almost the same high amount of isotactic sequences at 20, 50 and 80{dollar}\sp\circ{dollar}C Cat.3 produced polymers with isotactic sequences and syndiotactic sequences at both 0{dollar}\sp\circ{dollar}C and 80{dollar}\sp\circ{dollar}C, but produced polymer only with syndiotactic sequences at 20{dollar}\sp\circ{dollar}C. Cat.4 could produce polymer with high amount of isotactic sequences. Cat.5 could only produce atactic polymer at all temperatures. However, the activities of Cat.2, Cat.3 and Cat.4 were pretty low.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
