Copolymerization of Ethylene with α-Olefins at High Temperature and Characterization of Copolymers

Takaoka, Tooru; Ikai, Shigeru; Tamura, Masanori; Yano, Takefumi

doi:10.1080/10601329508011066

Cited by 10 publications

(9 citation statements)

References 14 publications

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“…Spacing in the symmetrical monomer directly determines precision run lengths in the polymer; prior monomer synthetic schemes have limited the maximum run lengths between branch points along the polymer to 20 methylene carbons (i.e., a branch placed on each and every 21st carbon along polyethylene’s backbone). ,, While we have been able to examine polymers with more frequent branch placement (as frequent as every fifth carbon, for example), producing ADMET polyethylene with less frequent branch placement had escaped our efforts. Less frequent branching would allow us to generate model polymers more reflective of commercial polyethylene, whose structure has been studied via more conventional methodology for decades. , …”

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confidence: 99%

“…Less frequent branching would allow us to generate model polymers more reflective of commercial polyethylene, whose structure has been studied via more conventional methodology for decades. 10,11 We now report the synthesis and characterization of precision polyethylene possessing a butyl branch on every 39th carbon (38 methylenes between branch points). Complete primary structure characterization is included in this Communication, as is the first morphological examination by wide-angle X-ray diffraction (WAXS) analysis.…”

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confidence: 99%

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Reducing Branch Frequency in Precision Polyethylene

et al. 2009

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confidence: 99%

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confidence: 99%

Reducing Branch Frequency in Precision Polyethylene

et al. 2009

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“…For copolymerization of ethylene/1‐butene when the temperature increased from 50 to 120°C, the reactivity ratios decrease 30. Several factors can contribute to the temperature effect on the reactivity ratio value, including a diffusion limitation for heavier α‐olefin31 which can be serious at high temperature.…”

Section: Resultsmentioning

confidence: 99%

Copolymerization of ethylene/propylene elastomer using high‐activity Ziegler–Natta catalyst system of MgCl₂ (ethoxide type)/EB/PDMS/TiCl₄/PMT

Zohuri

Sadegvandi²,

Jamjah

et al. 2002

J of Applied Polymer Sci

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A high-activity Ziegler-Natta catalyst of TiCl 4 -supported MgCl 2 (ethoxide type) was prepared. Ethyl benzoate (EB) and polydimethylsiloxane (PDMS) were used as internal donors, while p-methyl toluate (MPT) and triethylaluminum (TEA) were used as the external donor and cocatalyst, respectively. Suspension copolymerization of ethylenepropylene (EPM) was carried out in n-heptane using the catalyst system. The relative pressures of 1.5 : 1 and 2 : 1 atmosphere of propylene-to-ethylene (P P /P E ) gave a polymer with elastomeric properties. The relative pressure of propylene-to-ethylene higher and lower than the above values, however, gave a homopolymer or copolymer without elastomeric properties. The effect of the TEA concentration, H 2 concentration, temperature, and pressure of P P /P E on the yield of the polymer obtained was investigated. The effects of these factors on the glass transition temperature (T g ) and ethylene content of the polymer were studied. The content of ethylene in EPM was determined using the FTIR technique. The molar ratio of Al : MPT : Ti ϭ 355 : 107 : 1 gave a polymer with an ethylene content of about 32%. However, a ratio lower than AL : MPT : Ti ϭ 355 : 107 : 1 did not give a good elastomeric polymer. The highest productivity of the catalyst was obtained at a molar ratio of AL : MPT : Ti ϭ 355 : 107 : 1. Increasing the temperature from 45 to 70°C caused a slight increase of Et % content and a decrease of the T g of the copolymer obtained, while the highest productivity of the catalyst was obtained at 55°C with good elastomeric properties using an AL : MPT : Ti ϭ 497 : 107 : 1 molar ratio. Increasing the pressure of propylene from 1.5 to 2.5 atm caused a sharp decrease in the T g and ethylene content of the polymer. When the ethylene content in the copolymer was increased, the T g value had a tendency to be closer to the polyethylene T g .

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“…Such polymerization mechanisms are often described by of a large number of simultaneous reactions. This is especially true if it is assumed that each catalyst may contain more than one type of active site, which is a widely believed explanation for the broad and multimodal CL and CC distributions found experimentally (Usami et al, 1986;Wild, 1991 ;Takaoka et al , 1995;Williams, 1996). Another possible explanation for broad distributions is diffusion limita tion to mass transfer (Galvan , 1986) , which could occur as the catalyst becomes coated with polymer during the reaction , thereby limiting the access of the monomers to the active sites.…”

Section: Reaction Mechanismsmentioning

confidence: 93%

“…In this way, the entire joint CL and CC distribution can be determined (Wild et a!. , 1982;Usami et a!., 1986;Wild, 1991 ;Soares , 1994;Hungenberg et a!., 1995;Takaoka et a!., 1995;Williams, 1996).…”

Section: Instantaneous Joint Chain Length and Composition Distributionmentioning

confidence: 98%

Simulating Joint Chain Length and Composition Fractions from Semi-Batch Ethylene Copolymerization Experiments

Shaw

McAuley

Bacon

1998

Polymer Reaction Engineering

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Linear low density polyethylenes produced using a-olefin comonomers and heterogeneous Ziegler-Natta catalysts have broad chain length (CL) and copolymer composition (CC) distributions. Multiple types of active sites on the catalyst are the cause of these broad and often multimodal distributions that influence both end-use and processing behaviour of the copolymer. Measurement of the joint CL and CC distribution can be accomplished by crossfractionating polyethylene by Temperature Rising Elution Fractionation (TREF) and Size Exclusion Chromatography (SEC). Using these techniques, copolymer can be separated into bins corresponding to specific CC and CL ranges. In this article, Stockmayer's (1945) bivariate distribution is used to develop a methodology for modelling the quantity of accumulated copolymer that corresponds to each specific bin of the joint CL and CC distribution. First, the instantaneous joint CL and CC distribution for polymer produced at each site type is integrated over specified finite ranges of composition and chain length. The end points of these ranges correspond to TREF fraction composition limits and selected chain lengths from SEC analyses. The instantaneous rate of polymer production from all site types in each of the bins is then calculated. The polymer accumulated in each bin over the course of a polymerization experiment is determined by numerically solving a set of ordinary differential equations. This methodology can be used to predict experimental TREF and SEC cross-fractionation results for copolymer produced dynamically in semi-batch laboratory reactors. The resulting predictions can then be used with experimental results to estimate parameters in kinetic models describing ethylene copolymerization with multiple active site catalysts.

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Copolymerization of Ethylene with α-Olefins at High Temperature and Characterization of Copolymers

Cited by 10 publications

References 14 publications

Reducing Branch Frequency in Precision Polyethylene

Reducing Branch Frequency in Precision Polyethylene

Copolymerization of ethylene/propylene elastomer using high‐activity Ziegler–Natta catalyst system of MgCl₂ (ethoxide type)/EB/PDMS/TiCl₄/PMT

Simulating Joint Chain Length and Composition Fractions from Semi-Batch Ethylene Copolymerization Experiments

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Copolymerization of Ethylene with α-Olefins at High Temperature and Characterization of Copolymers

Cited by 10 publications

References 14 publications

Reducing Branch Frequency in Precision Polyethylene

Reducing Branch Frequency in Precision Polyethylene

Copolymerization of ethylene/propylene elastomer using high‐activity Ziegler–Natta catalyst system of MgCl2 (ethoxide type)/EB/PDMS/TiCl4/PMT

Simulating Joint Chain Length and Composition Fractions from Semi-Batch Ethylene Copolymerization Experiments

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Copolymerization of ethylene/propylene elastomer using high‐activity Ziegler–Natta catalyst system of MgCl₂ (ethoxide type)/EB/PDMS/TiCl₄/PMT