Influence of the catalyst and polymerization conditions on the long‐chain branching of metallocene‐catalyzed polyethenes

Kokko, Esa; Malmberg, Anneli; Lehmus, Petri; Löfgren, Barbro; Seppälä, Jukka V.

doi:10.1002/(sici)1099-0518(20000115)38:2<376::aid-pola12>3.3.co;2-x

Cited by 46 publications

(113 citation statements)

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“…Final melting endotherms were obtained by the polymer being heated to 170°C (10°C /min). 13 C NMR spectra were recorded on a Bruker Avance 400 spectrometer. The acquisition time was 2 s, the delay time between pulses was 7 s, and the number of scans was 6000.…”

Section: Polymer Characterizationsupporting

confidence: 60%

“…11 The ligand structure also influences the termination mechanisms and, consequently, the end groups of the polymers. 12,13 The ratio between vinyl and trans-vinylene unsaturation is approximately 6/1 with Cp 2 ZrCl 2 and 1/1 with Cp* 2 ZrCl 2 . 12 The objective of this work is to investigate the homopolymerization of ethene and the copolymerization of ethene and 1-hexene with zirconocene catalysts containing different methyl-substituted cyclopentadienyl (Cp) ligands.…”

Section: Introductionmentioning

confidence: 99%

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Ethene homopolymerization and copolymerization with 1-hexene for all methyl-substituted (RnC5H5?n)2ZrCL2/MAO catalytic systems: Effects of split methyl substitution

Wigum¹,

Tangen²,

Støvneng³

et al. 2000

J. Polym. Sci. A Polym. Chem.

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Section: Polymer Characterizationsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Ethene homopolymerization and copolymerization with 1-hexene for all methyl-substituted (RnC5H5?n)2ZrCL2/MAO catalytic systems: Effects of split methyl substitution

Wigum¹,

Tangen²,

Støvneng³

et al. 2000

J. Polym. Sci. A Polym. Chem.

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“…As it has been shown in literature that the zero shear-rate viscosity enhancement factor h 0 =h lin 0 very sensitively reflects the influence of LCB, [6,7,9,14,19,30,[39][40][41] some kind of relationship may exist. If n is plotted versus log(h 0 =h lin 0 ), a linear relation is found to be a good approximation, as Figure 6 demonstrates.…”

Section: Correlation Between the Characteristic Relaxation Time L 1 Amentioning

confidence: 95%

“…[6][7][8][9] For lower molar masses h 0 =h lin 0 < 1 might be observed. [10] Alternatively, it has been proposed that the dependence of the phase angle, d, on the magnitude of the complex modulus, jG Ã j, may be used for the detection of long-chain branches.…”

Section: Introductionmentioning

confidence: 98%

Correlations between the Shape of Viscosity Functions and the Molecular Structure of Long‐Chain Branched Polyethylenes

Stadler

Münstedt

2009

Macro Materials & Eng

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The viscosity functions of long‐chain branched metallocene‐catalyzed ethene homopolymers and copolymers (LCB‐mPE) were described by an extended Carreau‐Yasuda model. The two characteristic relaxation times, λ1 and λ2, and the slope of the viscosity function between these two characteristic relaxation times can be correlated to the zero shear‐rate viscosity, η0, and the molar mass $\overline M _{\rm w} $. The characteristic relaxation times, λ1 and λ2 (describing the main curvatures of the viscosity function) exhibit a power law dependency on the molar mass, $\overline M _{\rm w} $. The parameterization of the viscosity function can be used for a molecular characterization and flow simulations of various kinds.magnified image

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“…For example, the vinyl bond content can be calculated from the absorbance peak of 908 cm −1 using the method described by Haslam et al [187] The end-group information can be used to study the polymerization mechanisms. [13,188,189] But nowadays, FTIR alone is not commonly used for quantitative analysis due to limitations of the resolution.…”

Section: Ftirmentioning

confidence: 98%

A Comprehensive Review on Controlled Synthesis of Long‐Chain Branched Polyolefins: Part 3, Characterization of Long‐Chain Branched Polymers

Liu

Wang

et al. 2016

Macro Reaction Engineering

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Synthesis and characterization of long-chain branched polyolefins has been an important research topic for both academic and industrial researchers for many decades. This is particularly true since the discovery and successful commercialization of the constrained geometry catalyst systems in 1990s. The type of single site catalysts allows control in the synthesis and the precision in the characterization. Long-chain branched polyolefins exhibit improved melt processability, such as higher melt strength and better shear thinning, compared to their linear counterparts having the same molecular weight and distribution. In the previous papers, the catalyst systems and reaction conditions for the controlled synthesis of long-chain branched polyolefins have been reviewed. This paper aims at summarizing the literatures pertinent to the precise characterization of long-chain branched polyolefins. The major methods of long-chain branching characterization include: nuclear magnetic resonance, gel permeation chromatography, rheometry, dynamical mechanical analysis, differential scanning calorimetry, neutron scattering, and Fourier transform infrared spectroscopy. Recent progresses of these characterization methods, as well as their advantages and limitations, have been discussed in details.

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Influence of the catalyst and polymerization conditions on the long‐chain branching of metallocene‐catalyzed polyethenes

Cited by 46 publications

References 0 publications

Ethene homopolymerization and copolymerization with 1-hexene for all methyl-substituted (RnC5H5?n)2ZrCL2/MAO catalytic systems: Effects of split methyl substitution

Ethene homopolymerization and copolymerization with 1-hexene for all methyl-substituted (RnC5H5?n)2ZrCL2/MAO catalytic systems: Effects of split methyl substitution

Correlations between the Shape of Viscosity Functions and the Molecular Structure of Long‐Chain Branched Polyethylenes

A Comprehensive Review on Controlled Synthesis of Long‐Chain Branched Polyolefins: Part 3, Characterization of Long‐Chain Branched Polymers

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