Effects of propylene prepolymerization on ethylene/1‐hexene and ethylene/1‐octene copolymerization with an immobilized metallocene catalyst

Smit, M Madri; Zheng, Xuejing; Loos, Joachim; Chadwick, JC John; Koning, CE Cor

doi:10.1002/pola.21566

Cited by 17 publications

(14 citation statements)

References 21 publications

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“…This result was in contrast to the previous reports that 1-Oct is usually less active than 1-Hex. 10 The molecular weights of the resultant P(E-co-Hex)s and P(E-co-Oct)s became lower when the comonomer incorporation ratio was higher. The presence of the α-olefin might accelerate βhydrogen elimination reaction in the copolymerization process as well as the chain-transfer reaction toward α-olefins.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Copolymerization of Ethylene with 1-Hexene and 1-Octene Catalyzed by Fluorenyl N-Heterocyclic Carbene Ligated Rare-Earth Metal Precursors

Yao

Wang

et al. 2013

Organometallics

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Rare-earth metal bis(alkyl) complexes (Flu–NHC)Ln(CH2SiMe3)2 (Ln = Dy (1), Er (2), Sc (3)) attached by fluorenyl-modified N-heterocyclic carbene ligands ((Flu H–NHC–H)Br) have been synthesized by treatment of (FluH–NHC–H)Br with (trimethylsilylmethyl)lithium (LiCH2SiMe3) and rare-earth metal tris(alkyl)s (Ln(CH2SiMe3)3(THF)2) via double-deprotonation reactions in moderate to high yields. Under mild conditions (40 °C and normal ethylene pressure), the scandium precursor 3, upon activation of Al i Bu3 and [Ph3C][B(C6F5)4], showed high activity (4120 kg molSc –1 h–1 atm–1) for the copolymerization of ethylene and 1-hexene with moderate 1-hexene insertion ratio (20.2%), although the analogous complexes 1 and 2 were inert. In addition, this system displayed excellent catalytic performances for the copolymerization of ethylene and a higher α-olefin 1-octene with an activity of up to 3640 kg molSc –1 h–1 atm–1. The content of 1-octene could be controlled swiftly from 2.1% to 38.7% by varying the 1-octene feed ratio. Thus the isolated P(E-co-Oct) polymers varied from opaque crystalline solids with high melting points, e.g., T m = 103.6 °C, to transparent elastomers. This represents the first rare-earth metal based homogeneous catalyst that can initiate the copolymerization of ethylene and 1-octene, the catalytic performances of which are comparable with those reported for the most active group 4 metallocene systems.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Copolymerization of Ethylene with 1-Hexene and 1-Octene Catalyzed by Fluorenyl N-Heterocyclic Carbene Ligated Rare-Earth Metal Precursors

Yao

Wang

et al. 2013

Organometallics

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“…In several studies in which SiO 2 has been used as support, it has been observed that the initial fragmentation of this support normally proceeds layer by layer. This has been shown with a Ziegler–Natta catalyst for polyethylene17 and with single‐site catalysts for polypropylene (PP)18–20 and polyethylene 21, 22. The strength and dimensions of the interconnecting network, in addition to the total pore volume, are important factors in the control of fragmentation and nascent polymerization with silica‐based catalysts 23–26…”

Section: Introductionmentioning

confidence: 98%

“…This has been shown with a Ziegler-Natta catalyst for polyethylene 17 and with single-site catalysts for polypropylene (PP) [18][19][20] and polyethylene. 21,22 The strength and dimensions of the interconnecting network, in addition to the total pore volume, are important factors in the control of fragmentation and nascent polymerization with silicabased catalysts. [23][24][25][26] More recently, there have been reports in the literature of a catalyst that has neither a measurable surface area nor porosity by Brunauer-Emmet-Teller (BET) analysis but still has a high activity and good powder morphology.…”

Section: Introductionmentioning

confidence: 99%

Porous versus novel compact Ziegler–Natta catalyst particles and their fragmentation during the early stages of bulk propylene polymerization

Vestberg

Denifl

Wilén

2008

J of Applied Polymer Sci

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The effect of the porosity of Ziegler-Natta catalyst particles on early fragmentation, nascent polymer morphology, and activity were studied. The bulk polymerization of propylene was carried out with three different heterogeneous Ziegler-Natta catalysts under industrial conditions at low temperatures, that is, with a novel selfsupported catalyst (A), a SiO 2 -supported catalyst (B), and a MgCl 2 -supported catalyst (C), with triethyl aluminum as a cocatalyst and dicyclopentyl dimethoxy silane as an external donor. The compact catalyst A exhibited no measurable porosity and a very low surface area (<5 m 2 /g) by Brunauer-Emmet-Teller analysis, whereas catalysts B and C showed surface areas of 63 and 250 m 2 /g, respectively. The surface and cross-sectional morphologies of the resulting polymer particles at different stages of particle growth were analyzed by scanning electron microscopy and transmission electron microscopy. The compact catalyst A showed homogeneous and instantaneous fragmentation already in the very early stages of polymerization, which is typically observed for porous MgCl 2 -supported Ziegler-Natta catalysts. Moreover, the compact catalyst particles gave rise to almost perfectly spherical polymer particles with a smooth surface. In contrast, the silicasupported catalyst B gave rise to particles having a cauliflower morphology, and the second reference catalyst C produced fairly spherical polymer particles with a rough surface. All of the three catalysts exhibited similar activities of 450 g of polypropylene/g of catalyst after 30 min of polymerization, and most interestingly, the comparative kinetic data presented indicated that the reaction rates were not influenced by the porosity of the catalyst.

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“…The images selected are representative of a general trend observed, where the use of 1-butene as comonomer yields a polymer with less evidence of stretched fibrils. Their presence have been associated with diffusion limitations, [18] supporting as possible reason the beneficial effect of comonomer on the activity related with the better monomers diffusion during the reaction, as it was suggested previously. [13][14][15] Besides, it is well known that mass transfer restrictions lead to broader molecular weight distributions.…”

Section: Resultsmentioning

confidence: 66%

Ethylene/1‐Butene Copolymerization over Heterogeneous Metallocene Catalyst

Grieken

Martı́n

Moreno

et al. 2007

Macromolecular Symposia

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Summary: Nowadays, bimodal polyethylene obtained in a two step cascade process is a matter of intensive research in polyolefin field. In the second stage of this process, a high molecular weight ethylene-a-olefin copolymer is formed over the homopolymer produced in the first step. In this work, a study of reaction variables on this second step using an heterogeneous metallocene catalyst was carried out. The effect of reaction temperature (70-85 8C) and comonomer concentration (0-0.32 mol/l) was evaluated. Polymerization results showed that activity increases with temperature and 1-butene initial concentration. Moreover, higher comonomer concentrations and lower temperatures involve higher short chain branching (SCB). Copolymers characterization indicated that melt temperature and density values have a lineal decrease with the SCB content in the polymer, regardless of the reaction temperature. As well, for every temperature, higher comonomer concentrations do not seem to affect to molecular weight, whereas a decrease of crystallinity was observed, which may explain the increase of catalyst activity.

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Effects of propylene prepolymerization on ethylene/1‐hexene and ethylene/1‐octene copolymerization with an immobilized metallocene catalyst

Cited by 17 publications

References 21 publications

Copolymerization of Ethylene with 1-Hexene and 1-Octene Catalyzed by Fluorenyl N-Heterocyclic Carbene Ligated Rare-Earth Metal Precursors

Copolymerization of Ethylene with 1-Hexene and 1-Octene Catalyzed by Fluorenyl N-Heterocyclic Carbene Ligated Rare-Earth Metal Precursors

Porous versus novel compact Ziegler–Natta catalyst particles and their fragmentation during the early stages of bulk propylene polymerization

Ethylene/1‐Butene Copolymerization over Heterogeneous Metallocene Catalyst

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