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Study on the Modified Supported Ziegler-Natta Catalyst Systems for the Copolymerization of Ethylene with Higher α-Olefins

Author: KongZuo
Tutor: HuangQiGu
School: Beijing University of Chemical Technology
Course: Macromolecular Chemistry and Physics
Keywords: A modified load Ziegler-Natta catalyst Olefin copolymers Polymer microstructure An electron donor
CLC: O631
Type: Master's thesis
Year: 2010
Downloads: 98
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Abstract


Ethylene and α-olefins such as 1 - butene, 1 - hexene, 1 - octene copolymer is a polymer material. Usually due to short chain branching the copolymer of the α-olefin having a low melting point, low crystallinity and low density. 1 - hexene and 1 - octene as co-monomer synthesis copolymers mechanical properties significantly better than the 1 - butene as the comonomer of the polyolefin product. In this thesis as a starting point, two modified prepared new load Ziegler-Natta catalyst system catalyzed ethylene with long-chain alpha-olefins (1 - hexene and 1 - octene) polymerization of high-performance ethylene copolymer. This thesis is divided into two parts: (iso-PentylO) TiCl3/MgCl2/Et3Al (II) and (BzO) TiCl3/MgCl2/Et3Al (III) catalyst system catalyzed ethylene / 1 - octene polymerization; TiCl4/ROH / MgCl2/Et3Al catalytic systems catalyzed ethylene / 1 - hexene copolymerization. Part I: catalytic ethylene the new modified load Ziegler-Natta catalyst system (iso-PentylO) the TiCl3/MgCl2/Et3Al (II) and (BzO) TiCl3/MgCl2/Et3Al (Ⅲ) / 1 - octene copolymerization. The effects of the ligand structure of the catalyst, Al / Ti molar ratio, temperature, monomer feed than the insertion amount on the catalytic activity, the monomer, the copolymer molecular weight and the copolymer microstructure. WAXD, DSC, 13C-NMR copolymer structure and properties were characterized. The results show that the modified Ziegler-Natta catalyst system (II) and (III)-catalyzed ethylene / 1 - octene copolymerized 1 - octene significantly higher than the traditional Ziegler-Natta catalytic system (TiCl4/MgCl2/Et3Al of (I)), in the copolymer in 1 - octene molar content respectively 2.26mol% and 7.46 mol%. Traditional Ziegler-Natta catalyst (I)-catalyzed ethylene / 1 - octene copolymerization, 1 - octene molar insert only 0.34 mol%. The monomer feed ratio on the activity of the catalyst, - the amount of insertion of octene, the micro structure of the molecular weight of the copolymer and the copolymer has a significant impact. Modified Ziegler-Natta catalyst system (II) and (III) catalyzed ethylene / 1 - octene copolymerization behavior based on the results of the 13C-NMR studies, copolymer of monomer reactivity ratios were: rE = 55.00, rO = 0.023 and rE = 17.15, rO = 0.055, whose product = 1.27 and rE rO = 0.93, respectively, for rE · rO. Show that the polymers are random copolymers. Part II: MgCl2 load by TiCl4, 1 - octanol to electronic body (ROH), the composition of the catalyst system with the triethylaluminum cocatalyst, Synthesis of 1 - hexene is high and wide molecular weight distribution of the ethylene / 1 - hexene copolymer. Discussed the composition of the catalytic system, ratio, the polymerization conditions on the behavior of ethylene / 1 - hexene copolymerization, the copolymer structure, the copolymer molecular weight and molecular weight distribution of the impact, the results show that the n (Ti) / n (Mg) is 10: 1; n (ROH) / n (MgCl2) was 1.5:1; n (Al) / N (Ti) of 100:1; ethylene pressure P was 0.12 MPa; polymerization temperature T of 70 ° C; polymerization time t 1H; comonomer (1-hexene), a concentration of 0.25mol / L, the catalytic activity of 0.76 kg / g cat.h. 13C NMR, SEM, WAXD, DSC, GPC, TG, FT-IR and other methods to characterize the structure and properties of catalyst, the copolymer. The results show that the electron donor in the Ziegler-Natta catalyst system, 1 - octanol and TiCl4 combination, a change in the crystal structure of the carrier of MgCl2, lower degree of crystallinity, conducive to increased catalyst loading, the catalytic efficiency is increased; catalytic system generated A variety of active centers, the polyolefin molecular weight distribution broadens; 1 - octanol also enhance the 1 - hexene copolymerization with ethylene, 1 - hexene mole fraction of up to 2.6 mol% in the copolymer.

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CLC: > Mathematical sciences and chemical > Chemistry > Polymer chemistry ( polymer ) > Polymer physics and physical chemistry of polymers
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