Copolymerization of ethylene and ?-olefins with combined metallocene catalysts. III. Production of polyolefins with controlled microstructures

Kim, Jung Dae; Soares, João B. P.

doi:10.1002/(sici)1099-0518(20000501)38:9<1427::aid-pola4>3.0.co;2-y

Cited by 64 publications

(42 citation statements)

References 12 publications

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“…Examples mainly include production of bimodal MWD by hybrid catalyst (both catalysts supported on the same support) [19][20][21][22][23]. Further, application of mixed homogenous and/or heterogeneous dual metallocene systems or the corresponding hybrid catalysts was seen to have more flexibility for control of chain microstructure [24][25][26][27]. Kim et al [25] utilized metallocenes with different hydrogen response to tune MWD from unimodal to bimodal distribution by changing hydrogen concentration.…”

Section: Introductionmentioning

confidence: 99%

“…Further, application of mixed homogenous and/or heterogeneous dual metallocene systems or the corresponding hybrid catalysts was seen to have more flexibility for control of chain microstructure [24][25][26][27]. Kim et al [25] utilized metallocenes with different hydrogen response to tune MWD from unimodal to bimodal distribution by changing hydrogen concentration. Hong et al [26] used metallocenes with different capability of comonomer incorporation to provide bimodal MWD with inverse comonomer content.…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of linear/branched polyethylene reactor blends synthesized by metallocene/late transitional metal hybrid catalysts

Mortazavi

Jafarian

Ahmadi

et al. 2015

J Therm Anal Calorim

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Nickel diimine late transition metal (LTM) and Cp 2 TiCl 2 metallocene catalysts were supported on the TIBA-modified MgCl 2 ÁnEtOH adduct, separately and concurrently, at different ratios, to yield hybrid catalysts, where the catalytic precursors were activated in the ethylene polymerization with TEA as the cocatalyst. Polymerization activities revealed that supported LTM catalysts show very high levels of activity, in an adverse trend with polymerization temperature ranging from 30 to 70°C, in opposition to the activity of metallocene component. Consequently, the proportion of corresponding polymer fractions were tuned by changing reaction temperature as well as catalyst composition. Study of thermal properties confirmed that LTM component is responsible for production of less crystallizable branched chains, while metallocene fraction makes highly crystallizable linear chains. All samples showed noticeable thermorheological complexity due to coexistence of linear and branched microstructures. Interestingly, it was found that increase in metallocene fraction of the hybrid catalyst stalls the terminal relaxation of the produced polymers and increases the entanglement density by decreasing the extent of branching. Study of dynamic mechanical properties revealed that the intensity of b transition could be correlated with the branching level and catalyst composition accordingly.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characteristics of linear/branched polyethylene reactor blends synthesized by metallocene/late transitional metal hybrid catalysts

Mortazavi

Jafarian

Ahmadi

et al. 2015

J Therm Anal Calorim

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“…Similar results can be achieved by physical blending of polymers with the desired properties [2]. In addition, a mixture of two or more metallocene catalysts can be used to produce polymers with tailored properties in one reactor [3][4][5][6][7][8][9][10]. Dual-site catalysts can be further fine-tuned by changing polymerization conditions [11,12].…”

Section: Introductionmentioning

confidence: 85%

Crystallization analysis fractionation of ethene/1-hexene copolymers made with the MAO-activated dual-site (1,2,4-Me3Cp)2ZrCl2 and (Me5Cp)2ZrCl2 system

Bruaseth

Soares

Rytter

2004

Polymer

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“…Several reviews and patents have been published about recent advances in olefin polymerization using binary catalyst systems 9–15. Catalysts can be combined in three ways: (1) in the catalyst transition, the second catalyst is introduced to the reactor in the middle of polymerization and can continue polymerization with or without (by deactivating) the first catalyst;16–19 (2) in the catalyst mixture, two independent catalysts are introduced to the reactor and start the polymerization together;16–27 (3) two catalysts can also be loaded on a support to form a new catalyst, named a hybrid catalyst 28–44…”

Section: Introductionmentioning

confidence: 99%

Ziegler‐Natta/Metallocene Hybrid Catalyst for Ethylene Polymerization

Ahmadi

Jamjah

Nekoomanesh

et al. 2007

Macro Reaction Engineering

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A Ziegler‐Natta/metallocene hybrid catalyst was produced and utilized in the polymerization of ethylene with the aim of producing bimodal polyethylene. The MgCl2 adduct was prepared by a melt quenching method and Cp2ZrCl2 and TiCl4 catalysts were loaded, respectively, after treating the surface with TiBAl. The polymerization kinetics involved an induction period, followed by fragmentation and expansion of particles. SEM micrographs revealed that the spherical morphology was retained through the initial mild reaction conditions of induction period. The polymers produced showed bimodal molecular weight distribution patterns, suggesting that both components of the hybrid catalyst were active over the support.

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Copolymerization of ethylene and ?-olefins with combined metallocene catalysts. III. Production of polyolefins with controlled microstructures

Cited by 64 publications

References 12 publications

Characteristics of linear/branched polyethylene reactor blends synthesized by metallocene/late transitional metal hybrid catalysts

Characteristics of linear/branched polyethylene reactor blends synthesized by metallocene/late transitional metal hybrid catalysts

Crystallization analysis fractionation of ethene/1-hexene copolymers made with the MAO-activated dual-site (1,2,4-Me3Cp)2ZrCl2 and (Me5Cp)2ZrCl2 system

Ziegler‐Natta/Metallocene Hybrid Catalyst for Ethylene Polymerization

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