• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1028-1029
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• 2003

The copolymerization of ethylene and norbornene was carried out with ansa-metallocene and modified methylaluminoxane (MMAO) cocatalyst. The copolymerization behavior was changed with the structure of metallocene catalysts. In addition the catalyst activity was dependent on the structure of MMAO, i.e.. MMAO-4 which contains less i-butyl group compared to MMAO-3A exhibited higher catalyst activity than MMAO-3A. The glass transition temperature and the composition of the produced copolymer were not affected by MMAO type.

• Macromolecular Research
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• v.9 no.2
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• pp.71-83
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• 2001

The metallocene compounds had been applied to the polymerizations of olefins and vinyl monomers with methylaluminoxane (MAO) cocatalyst, and they have usually one transition metal atom per molecule, i.e., mononuclear metallocene. Recently it has been found that the dinuclear metallocene compounds containing two transition metal atoms exhibit the peculiar polymerization behaviors for olefins and vinyl monomers. In this article, the dinuclear metallocenes are classified into four groups of dinuclear bent-metallocene, dinuclear ansa-metallocene, dinuclear constrained geometry catalyst and dinuclear half-metallocene, and then the synthesis of dinuclear metallocene of each group as well as the polymerization behaviors for ethylene, propylene, and styrene are described.

• Polymer Science and Technology
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• v.5 no.3
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• pp.189-199
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• 1994

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.123-127
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• 2000

In order to investigate the influence of manufacturing process on the electrical properties, we used two kinds of low density polyethylene prepared using metallocene catalyst (mL), linear low density polyethylene prepared using Ziegler catalyst (LL) and low density polyethylene by high pressure process (LD). mL has the narrowest composition and molecular weight distributions. We measured the dc and impulse breakdown strengths and current densities at 3$0^{\circ}C$, 6$0^{\circ}C$ and 9$0^{\circ}C$. mL had a higher breakdown strength and a lower high-field current than LD and LL. These results were discussed from the point of manufacturing processes.

• Bulletin of the Korean Chemical Society
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• v.19 no.12
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• pp.1310-1314
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• 1998

The oligo(methylsilene) (1) was treated with the group 4 metallocene Cp2MCl2/Red-Al (M = Ti, Zr, Hf) combination catalysts and with the group 6 metal carbonyl M(CO)6 (M = Cr, W) catalysts, producing the modified, cross-linked polymers. The average molecular weights and percent ceramic residue yields of modified polymers increase as the catalyst goes down from Ti to Hf and similarly as the catalyst goes down from Cr to W. An interrelationship between average molecular weights and percent ceramic residue yield is found within the respective group of catalysts, but is not observed as the catalyst goes down from Ti to W. The polymers modified with the group 4 metallocene combination catalysts have higher molecular weights and similar percent ceramic residue yields as compared to the polymers modified with the group 6 metal carbonyl catalysts. The catalytic activities of group 4 metallocene combinations appear to be higher -100 ℃, but to be lower at very high temperature than those of group 6 metal carbonyls.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.857-865
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• 2017

This study was conducted to analyze and characterize the properties of polyethylene wax polymerized and polymerized using various metallocene catalysts based on Indene and Cyclopentadien, which are different from Ziegler-Natta catalysts used in polyethylene polymerizatio n. The polymerization of polyethylene wax was carried out under various conditions by adjusting the polymerization temperature and the ratio of hydrogen gas used as a chain transfer agent and ethylene gas to metallocene catalysts containing ligands of different structures. The molecular weight and molecular weight distribution, The catalyst yields were compared and analyzed. As a result, the structure of a metallocene catalyst suitable for having a low molecular weight and a narrow molecular weight distribution was proposed and the ideal polyethylene wax could be polymerized.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.698-705
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• 2016

In this study, we have studied the polymerization of polyethylene wax using metallocene catalysts and its physical properties. Various polymerization conditions were tried for polymerization of polyethylene wax. We have evaluated hydrogen reactivity and studied on characteristics of polymerization effected by ligand structure of metallocene catalysts against Ziegler-Natta catalysts which are widely used for polymerization of polyethylene. We have also checked hydrogen used for chain transfer agent, molecular weight change and distribution by different ratios of ethylene gas. Finally, we suggest proper structure of metallocene catalysts for polymerization of polyethylene wax.

• Elastomers and Composites
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• v.54 no.4
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• pp.286-293
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• 2019

In this study, flexible poly(ethylene-ter-1-hexene-ter-divinylbenzene) was prepared using four types of metallocene catalysts (rac-Et(Ind)₂ZrCl₂, rac-SiMe₂(Ind)₂ZrCl₂, rac-SiMe₂(2-Me-Ind)₂ZrCl₂, (C₅Me₅)TiCl₂[O-2,6-ⁱPr₂(C₆H₃)]) and two types of borate catalysts (trityl tetrakisborate and dimethylanilinium tetrakisborate). The yield, catalytic activity, molecular weight, structure, composition, and thermal properties of the terpolymers prepared using the various catalysts and cocatalyst systems were evaluated. Epoxidation of the terpolymers was successfully performed and this transformation was studied by ¹H NMR and FTIR.

• Bulletin of the Korean Chemical Society
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• v.18 no.12
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• pp.1264-1268
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• 1997

The poly(methylsilene) (1) was modified with the group 4 metallocene Cp2MCl2/Red-Al (M = Ti, Zr, Hf) combination catalyst and with the group 6 metal carbonyl M(CO)6 (M = Cr, Mo, W) catalyst, producing the highly cross-linked isoluble polymer and the lowly cross-linked soluble polymer, respectively. An interrelationship between molecular weight and percent ceramic residue yield with metal within the respective group was not found. The polymers modified with the group 4 metallocene combination catalysts have higher molecular weight and lower percent ceramic residue yield than the polymers modified with the group 6 metal carbonyl catalysts do. The catalytic activity of group 4 metallocene combinations appears to be higher at ∼100 ℃, but to be lower at very high temperature than those of group 6 metal carbonyls. The pyrolysis of the modified 1 yielded SiC ceramic.

• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.759-761
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• 2006

The compound B(C6F5)3 and its variations have been widely employed as alkyl carbanion abstracting reagents to produce metallocene cations for olefin polymerization.1-3 Weakly coordinating anions containing boron can greatly improve the activity of metallocene catalysts used in industrial olefin polymerization4 and thus group IV and V metallocene complexes of the organohydroborate anions have been intensively investigated.5 Recently, many organohydroborate metallocene complexes have been reported by Shore and co-workers.6-8 A common structural feature of those complexes is the three-center two electron M-H-B bond, like that observed in transition metal tetrahydroborate complexes but the reactivity and fluxional behavior of organohydroborate complexes are unlike those of the tetrahydroborate analogues.6 Although many of those metallocenes have been synthesized, few complexes could be used in the olefin polymerization and then this laboratory has been involved in the chemistry of the cyclic organohydroborate anions, and their group IV metallocene derivatives for the catalyst.9 Described here is recent work that led to the preparation of a novel cyclic organohydroborate hafnocene complex (h5-C5H5)2Hf ？(μ-H)2BC8H14 ,Cl. The hafnocene complex contains the three-center two electron bond Hf-H-B10 in which the hydride abstraction for olefin polymerization may occur.