Analytical and rheological characterization of long-chain branched metallocene-catalyzed ethylene homopolymers

Gabriel, Claus; Kokko, Esa; Löfgren, Barbro; Seppälä, Jukka; Münstedt, Helmut

doi:10.1016/s0032-3861(02)00564-5

Cited by 91 publications

(108 citation statements)

References 25 publications

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“…In similar vein, the steady-state recoverable elastic compliance, J 0 e is also correlated with LCB; unfortunately, it is also correlated in the same manner with molecular weight distribution which makes it hard to tease the apart the two effects [287][288][289][290]. In addition, the measurement of J 0 e is more time-consuming than that of η 0 , and in many practical cases steady state may not even be experimentally attainable [277,291].…”

Section: Experimental Methodsmentioning

confidence: 99%

Analytical Rheology of Polymer Melts: State of the Art

Shanbhag

2012

ISRN Materials Science

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The extreme sensitivity of rheology to the microstructure of polymer melts has prompted the development of "analytical rheology," which seeks inferring the structure and composition of an unknown sample based on rheological measurements. Typically, this involves the inversion of a model, which may be mathematical, computational, or completely empirical. Despite the imperfect state of existing models, analytical rheology remains a practically useful enterprise. I review its successes and failures in inferring the molecular weight distribution of linear polymers and the branching content in branched polymers.

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Section: Experimental Methodsmentioning

confidence: 99%

Analytical Rheology of Polymer Melts: State of the Art

Shanbhag

2012

ISRN Materials Science

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“…NMR spectroscopy, specifically 13 C NMR, is a direct technique used to quantitatively measure LCB in POs. Two types of 13 C NMR techniques are applied based on the physical state of samples.…”

Section: Nmrmentioning

confidence: 99%

Section: Nmrmentioning

confidence: 99%

“…Two types of 13 C NMR techniques are applied based on the physical state of samples. Whenever possible, liquid 13 C NMR is preferred with a deuterated solvent, otherwise solid melt 13 C NMR is employed. LCBD (the number of branches per 10 000 carbons) can be determined via liquid 13 C NMR through a quantitative measurement of the peak intensities for branched chain carbons versus backbone chain carbons.…”

Section: Nmrmentioning

confidence: 99%

“…Furthermore, MW, MWD, and short-chain branching (SCB) may all contribute to the characterization results, coupling with LCB, which makes the latter particularly difficult to discern. Nevertheless, the detection techniques including 13 C NMR, triple-detection GPC, rheometry, dynamic mechanical analysis (DMA), IR, and many others, have been employed to study LCB formation in POs, branching topologies, and the effects of LCB on polymer material properties. This paper reviews these characterization methods and discusses their advantages and limitations.…”

Section: Introductionmentioning

confidence: 99%

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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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The bridged cyclopentadienyl indenyl (fluorenyl) zirconocene complexes for polyethylene macromonomers

Huang

et al. 2010

Applied Organom Chemis

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The synthesis of long-chain branched polyethylene includes the generation of vinyl-terminated polyethylene macromonomers and the copolymerization of these macromonomers with ethylene. Four new bridged cyclopentadienyl indenyl (fluorenyl) zirconocene complexes 1a-b, 2a-b were prepared and showed high activities for ethylene homopolymerization upon the activation of methylaluminoxane. The steric bulk of bridged substituent has a profound effect on the catalytic activity as well as on the molecular weight of resulting polyethylene. Complex 1b showed the highest activity of up to 5.32 × 10 6 g PE/(mol Zr h) for ethylene homopolymerization at 70• C, which was higher than that of Cp 2 ZrCl 2 . The polyethylenes produced with complexes 1a-d/MAO are mostly vinyl-terminated, possess low molecular weight and fit as macromonomers. The (p-MePh) 2 Cbridged cyclopentadienyl indenyl zirconocene complex 1a could produce polyethylene macromonomer with selectivity for the vinyl-terminal as high as 94.9%.

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Analytical and rheological characterization of long-chain branched metallocene-catalyzed ethylene homopolymers

Cited by 91 publications

References 25 publications

Analytical Rheology of Polymer Melts: State of the Art

Analytical Rheology of Polymer Melts: State of the Art

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

The bridged cyclopentadienyl indenyl (fluorenyl) zirconocene complexes for polyethylene macromonomers

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