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

Stadler, Florian J.; Münstedt, Helmut

doi:10.1002/mame.200800251

Cited by 43 publications

(36 citation statements)

References 48 publications

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“…Stadler and Münstedt [88,315] sought to use size-exclusion chromatography with multiangle laser light scattering (SEC-MALLS), and shear rheological measurements to analyze viscosity functions of LCB polyethylenes, by separating the influence of long-chain branching and molecular weight on rheology. Doerpinghaus and Baird [316] parameterized the pom-pom model, which describes the nonlinear rheology of BPs semiquantitatively [53,163,165,166,[317][318][319][320], to shear and extensional rheology for different levels of LCB.…”

Section: Experimental Methodsmentioning

confidence: 99%

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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%

“…They found rheology to be more sensitive to branching, as expected, but reported that a combination of both the methods resulted in better overall characterization. Some of the works previously referenced also employ multidetector methods [88,219,220,302,315].…”

Section: Experimental Methodsmentioning

confidence: 99%

Analytical Rheology of Polymer Melts: State of the Art

Shanbhag

2012

ISRN Materials Science

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“…Various shear viscosity functions for metallocene-catalyzed long-chain branched PEs were also reported. [96,113,114] An extended Carreau-Yasuda model, Equation (26), was introduced by Münstedt group [113] to describe the viscosity function of distinct metallocene-catalyzed PEs with long-chain branches…”

Section: Zero Shear Viscosity η 0 and Shear Thinning Behaviormentioning

confidence: 99%

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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“…All measurements were performed in the linear viscoelastic regime on a TA Instruments AR-G2 or ARES in nitrogen atmosphere. An in-depth description of the experimental methods for the rheological measurements is given elsewhere (Stadler and Münstedt 2009;Stadler et al 2006b). …”

Section: Methodsmentioning

confidence: 99%

On “modulus shift” and thermorheological complexity in polyolefins

Stadler

Chen

2015

Rheol Acta

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Sparsely branched polyolefins often exhibit a thermorheological complexity, which was reported to be maskable by a modulus shift. However, the only physical background for a modulus shift is a density change, and this influence factor is only small in the relatively narrow temperature regime accessible by polyolefins. This paper deals with the question, how this modulus shift can be caused by experimental artifacts and real effects. The physical background of these two contributions to a vertical activation energy, as well as a meaningfulness of the application of a modulus shift, is found not to be given for polyolefins, when measuring only in a temperature range between 130 and 230°C.

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

Cited by 43 publications

References 48 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

On “modulus shift” and thermorheological complexity in polyolefins

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