Linear low-density polyethylene synthesis promoted by homogeneous and supported catalysts

Galland, Griselda B.; Seferin, Marcus; Mauler, Raquel Santos; Santos, João Henrique Zimnoch dos

doi:10.1002/(sici)1097-0126(199908)48:8<660::aid-pi212>3.0.co;2-l

Cited by 54 publications

(42 citation statements)

References 23 publications

(16 reference statements)

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“…This behavior has been observed by several researchers using metallocene catalysts, [28,42] as a result of the lower polymerization rate of 1-hexene insertion, not compensated by the increase in monomer diffusion rate through the less crystalline copolymer. [44,45] It is also possible that the copolymer made at higher comonomer concentrations could be too ''soft'' to break the support particles effectively, failing to expose the less accessible active sites and reducing the apparent catalytic activity. [46] Figure 5 demonstrates that the carrier pore size has a strong influence on the ethylene polymerization kinetics.…”

Section: Resultsmentioning

confidence: 65%

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes

Paredes¹,

Grieken²,

Carrero³

et al. 2011

Macro Chemistry & Physics

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The influence of the support architecture (structure and pore size) on the activity of MAO/(nBuCp)2ZrCl2 heterogeneous catalysts in the polymerization of ethylene and 1‐hexene is studied through the characterization of the polymers' microstructure. SBA‐15 silica‐based mesostructured materials are synthesized with different pore sizes and compared with commercial silica. All SBA‐15 supported catalysts lead to higher catalytic activities than amorphous silica and give rise to ethylene/1‐hexene copolymers with bimodal CCD, which suggests that the carrier structure plays an important role not only in the global rate of the process but also in the copolymer composition. The structures and pore sizes of the support show a marked influence on the polymer CCD shape. magnified image

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Section: Resultsmentioning

confidence: 65%

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes

Paredes¹,

Grieken²,

Carrero³

et al. 2011

Macro Chemistry & Physics

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“…As mentioned, comonomer contents are sensitive to many factors, such as the structure of catalyst, type of catalyst activators and the initial concentration of comonomer in the system. When considering the initial concentration, it has been found that the initial comonomer concentration not only affects directly on the comonomer contents, but it also affects on the catalytic activity of system [5,6]. Therefore, in this present study the effect of the initial comonomer concentration in ethylene-1-hexene copolymerization with half-metallocene is investigated to determine both the catalytic performance and the specification of the obtained copolymers.…”

Section: Introductionmentioning

confidence: 99%

Ethylene-hexene copolymer derived from [t-butylfluorenylsilyl-amido] dimethyl titanium complex

Chaichana¹,

Khaubunsongserm²,

Praserthdam³

et al. 2010

Express Polym. Lett.

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Abstract. The copolymers of ethylene and 1-hexene were prepared with half-metallocene titanium complex ([t-BuNSiMe2Flu]TiMe2) and modified methylaluminoxane (MMAO). The initial concentrations of 1-hexene were varied to investigate how the different amounts of comonomer affect on the catalytic activity of copolymerization system and microstructure of the copolymers. It has been found that this catalytic system was not active for hexene polymerization, however, it can be active when ethylene was introduced to perform ethylene-hexene copolymerization. As comonomer, 1-hexene provides positive comonomer effect on the system although very high concentration of 1-hexene was introduced. However, the microstructures of the obtained copolymers, which were examined by 13 C-NMR need to be improved because with highly alternating sequence distribution of comonomer causing them losing some essential specific thermal properties.

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“…2 that the molecular weight of polyethylene obtained with [VO(acacen)]/EtAlCl 2 is much higher than that for copolymers, and that it decreases with the increase of comonomer concentration in the feed. Such effects were observed repeatedly for copolymerizations catalyzed by different catalytic systems [21,[35][36][37][38]. Lower molecular weights of polymers for increasing 1-octene concentrations may result from the chain transfer to comonomer and/or more favourable β-hydride elimination after comonomer incorporation.…”

Section: Resultsmentioning

confidence: 99%

Oxovanadium(IV) complexes with [ONNO]-chelating ligands as catalysts for ethylene homo- and copolymerization

et al. 2014

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Oxovanadium(IV) complexes with [ONNO]-type tetradentate Schiff base ligands: salen, acacen, aceten, acetph (H 2 salen = N,N′-ethylenebis(salicylideneimine), H 2 aceten = N,N′-ethylenebis(2-hydroxyacetophenoneimine), H 2 acacen = N,N′-ethylenebis(acetylacetonimine), H 2 a c e t p h = N , N ′ -p h e n y l e n e -1 , 2 -b i s (2-hydroxyacetophenoneimine)), were the first time investigated in ethylene polymerization and ethylene/1-octene copolymerization processes. In general, all these complexes are moderately active precatalyst for ethylene polymerization upon activation with EtAlCl 2 and they give high molecular weight linear polyethylenes. Their activity in copolymerization was found relatively low. However, they yielded copolymers with high 1-octene incorporation even at low comonomer concentrations in the feed. The catalytic performance in homo-and copolymerization was influenced by both the ligand structure and polymerization parameters (Al/ V molar ratio, polymerization temperature, comonomer feed concentration). In addition, the [VO(acacen)] was supported onto magnesium supports, and in the presence of various cocatalyst and at different reaction conditions it was screened as the catalyst of choice for ethylene homo-and copolymerization.

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Linear low-density polyethylene synthesis promoted by homogeneous and supported catalysts

Cited by 54 publications

References 23 publications

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes

Ethylene-hexene copolymer derived from [t-butylfluorenylsilyl-amido] dimethyl titanium complex

Oxovanadium(IV) complexes with [ONNO]-chelating ligands as catalysts for ethylene homo- and copolymerization

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Linear low-density polyethylene synthesis promoted by homogeneous and supported catalysts

Cited by 54 publications

References 23 publications

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)2ZrCl2 Supported on SBA‐15 Materials with Different Pore Sizes

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)2ZrCl2 Supported on SBA‐15 Materials with Different Pore Sizes

Ethylene-hexene copolymer derived from [t-butylfluorenylsilyl-amido] dimethyl titanium complex

Oxovanadium(IV) complexes with [ONNO]-chelating ligands as catalysts for ethylene homo- and copolymerization

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Product

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Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes