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High ?-olefin homopolymerization catalyzed by rac-Me2Si[Ind]2ZrCl2/MAO system and 13C-NMR spectroscopy of the poly(high-?-olefin)
No full textTemperature Programmed Decomposition of MgCl2/THF/TiCl4 Bimetallic Complex Catalyst and its Effect on the Homo-and Copolymer of Ethylene
No full textA MgC12/THF/TiC14bimetalliccomplexcatalyst was prepared by reacting magnesium chloride with titanium tetrachloride in tetrahydrofuran(THF). During the temperatureprogrammeddecomposition(TPD) of the bimetalliccomplex, THF and 1,4 dichlorobutane were identified by Mass spectroscopy(MS). THF decoordinated from Ti species reacted with adjacent Cl, resulting in the formation of 1, 4–dichlorobutane. When the MgC12/THF/TiC14bimetalliccatalyst (Mg/Ti=5.2) was heated below 108 °C, the catalytic activity of polymerization increased, while it decreased above 140 °C. In ethylene-1–hexene copolymerization, the lowest catalytic activity was obtained at the molar ratio of hexene to ethylene in monomer feed(CH/CE), 1.14 or 2.22. The comonomer distribution of copolymer prepared with thermally pretreated catalyst was more homogeneous than that of copolymer prepared without thermal treatment
A Study on the comonomer effect in ethylene-hexene copolymerization by thermally pretreated Zigler-Natta Catalyst
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Analysis of microstructure of ethylene/1-hexene copolymer prepared over thermally pretreated MgCl2/THF/TiCl4 bimetallic catalyst
No full textThermally pretreated catalysts were prepared by heating MgCl2/THF/ TiCl4 (TT-0) at 80 degrees C for 5 min (TT-1) and 60 min (TT-2), and at 108 degrees C for 5 min (TT-3) and 60 min (TT-4). Ethylene-l-hexene copolymers were prepared with these catalysts. The TT-1 catalyst produced more blocky and higher l-hexene content polymer than TT-0, 2, 3, and 4. Temperature rising elution fractionation (TREF) analysis was used to investigate the chemical composition distribution of the ethylene-l-hexene copolymer, exhibiting. bimodal distribution for TT-0 and trimodal for TT-1, 2, 3, and 4. A portion of higher hexene content of the copolymer markedly increased when the copolymerization was performed with TT-1, indicating that copolymerization active sites were newly generated. Portion of homopolyethylene increased drastically when the copolymerization was performed with TT-4, indicating that ethylene homopolymerization active sites were increased. Gel permeation chromatography (GPC) also revealed that three kinds of active sites existed on the catalyst. C-13-NMR spectrum of each fraction after TREF analysis suggested that the isospecific active site could polymerize I-hexene well, resulting in random and alternating copolymers. A scheme for generation of the active site and change of its nature during thermal treatment of bimetallic complex catalyst is propose
Synthesis and Characterization of New Zirconocene: Stereo-block propylene polymerization catalyst precursor
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