Characterization of long chain branching: Dilution rheology of industrial polyethylenes

Crosby, B.J.; Mangnus, Marc; Groot, W. de; Daniels, Rob; McLeish, Tom

doi:10.1122/1.1451083

Cited by 46 publications

(24 citation statements)

References 34 publications

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“…Crosby et al [333] suggested a dilution rheology method, where the concentration-dependent variation of η 0 , in conjunction with molecular theory and rudimentary molecular weight information, was able to quantify the LCB in different families of branched polyethylenes. Krause et al [334] used electron beam irradiation to introduce branching in isotactic polypropylene and studied it using SEC and linear/nonlinear rheological experiments.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Some of the more sophisticated model-driven techniques allow us to combine heterogeneous data like rheology and molecular weight distribution obtained from multiple detectors with molecular models by exploiting some a priori information about the sample. I have already mentioned several methods which explicitly employ models (whether molecular-based or phenomenological) to interpret experimental data [63,66,316,327,331,333]. The rest implicitly use a model, even though it may only be specified as an empirical correlation, and not really labeled as a "model."…”

Section: Model-driven Data-analysis 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%

Section: Model-driven Data-analysis Methodsmentioning

confidence: 99%

Analytical Rheology of Polymer Melts: State of the Art

Shanbhag

2012

ISRN Materials Science

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“…At higher branching content the terminal times falls exponentially with Z a . This strong dependence on Z a has been turned recently into analytic methods for the characterization of LCB in unknown melts [71,308]. In the latter case, the dependence of the zero-shear viscosity on polymer concentration, ²…¿ p † at levels near the melt can be turned into a quantitative evaluation of Z x .…”

Section: Complex Topologies: the Seniority Distributionmentioning

confidence: 99%

Tube theory of entangled polymer dynamics

McLeish

2002

Advances in Physics

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827

1,122

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The dynamics of entangled¯exible polymers is dominated by physics general to many chemical systems. It is an appealing interdisciplinary ®eld where experimental and theoretical physics can work closely with chemistry and chemical engineering. The role of topological interactions is particularly important, and has given rise to a successful theoretical framework: the`tube model'. Progress over the last 30 years is reviewed in the light of specially-synthesized model materials, an increasing palette of experimental techniques, simulation and both linear and nonlinear rheological response. Our current understanding of a series of processes in entangled dynamics:`reptation',`contour length¯uctuation' and`constraintrelease' are set in the context of remaining serious challenges. Especial attention is paid to the phenomena associated with polymers of complex topology or`long chain branching'.

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“…Because this feature is critical to the rheology of polymers, it is natural that attempts have been made to use rheology to quantify branching. The presence of LCB has a profound effect on the rheological properties of polymers, [45][46][47][48][49][50][51] especially metallocene-catalyzed polyethylenes. [52][53][54][55][56][57][58][59][60] Only LCB of the order of 2-3 times the entanglement molecular weight [21][22][23][24][25] strongly affects rheological behavior.…”

Section: Determination Of Lcb In Polymers With Rheologymentioning

confidence: 99%

Quantification of branching in disordered materials

Kulkarni

Beaucage

2006

J Polym Sci B Polym Phys

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ABSTRACT:The phenomenon of structural branching is ubiquitous in a wide array of materials: polymers, ceramic aggregates, polymeric networks, and gels. Branching has a strong influence on the structureproperty relationships of these materials. Despite the interdisciplinary importance and decades of effort, the analytical description and quantification of branching are weak. Existing techniques for polymers based on size exclusion chromatography and rheology are, at best, qualitative, and quantitative characterization techniques such as nuclear magnetic resonance spectroscopy and transmission electron microscopy (for ceramic aggregates) have limitations in providing routine quantification. For ceramic aggregates, theoretical work has dominated, and only a few publications on analytical studies exist to support the theory. Small-angle scattering of X-rays and neutrons can be used to quantify the branch content through application of concepts native to fractal geometry.

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Characterization of long chain branching: Dilution rheology of industrial polyethylenes

Cited by 46 publications

References 34 publications

Analytical Rheology of Polymer Melts: State of the Art

Analytical Rheology of Polymer Melts: State of the Art

Tube theory of entangled polymer dynamics

Quantification of branching in disordered materials

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