Novel mechanism for the formation of long-chain branching in polyethylene

Reinking, Mark K.; Orf, Gene Michael; McFaddin, Douglas

doi:10.1002/(sici)1099-0518(19981130)36:16<2889::aid-pola7>3.0.co;2-p

Cited by 35 publications

(10 citation statements)

References 17 publications

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“…Other LCB formation mechanisms, such as C-H bond activation, have been suggested for vanadiumbased polymerization catalysts but do not seem to be relevant for most single-site catalysts. [7] Some late transition metal catalysts, such as Ni-diimine complexes, can also produce short-chain branched polyolefins via the chainwalking mechanism, but in this case the formation of LCB is unlikely due to the random nature of the chain walking process. [8] It is possible to make useful polymerization reactor engineering inferences from this polymerization mechanism.…”

Section: Mechanism Of Lcb Formation With Single Site Catalystsmentioning

confidence: 99%

Polyolefins with Long Chain Branches Made with Single‐Site Coordination Catalysts: A Review of Mathematical Modeling Techniques for Polymer Microstructure

Soares

2004

Macro Materials & Eng

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Summary: Single‐site coordination polymerization catalysts are considered one of the most important developments on the technology of olefin polymerization during the last two decades. Among the several new capabilities of these catalysts is the ability to produce polymer molecules having narrow molecular weight distribution and long chain branches. These advances in polymer synthesis have stimulated the development of mathematical models to describe and predict several features of their molecular architectures. Many modeling techniques have been used for this purpose, including instantaneous distributions, population balances, the method of moments, and Monte Carlo simulations. This article reviews the mathematical models developed over the last decade to quantify the microstructure of polymers made with single‐site catalysts with special emphasis on the mechanism of long chain branch formation by terminal branching. magnified image

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Section: Mechanism Of Lcb Formation With Single Site Catalystsmentioning

confidence: 99%

Polyolefins with Long Chain Branches Made with Single‐Site Coordination Catalysts: A Review of Mathematical Modeling Techniques for Polymer Microstructure

Soares

2004

Macro Materials & Eng

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“…Long-chain branching in metallocene catalysis is believed to take place via a copolymerization route, in which a vinyl terminated PE chain is incorporated into a growing polymer chain. [1] Although there was another mechanism observed for vanadium catalysts and transferred to metallocenes, [2] the examination of the polymerization behavior of several metallocene compounds revealed that chain transfer mechanisms were catalyst specific. Depending on the catalyst structure, the termination of chain growth occurred via b-H elimination, chain transfer to the monomer, or chain transfer to the catalyst.…”

Section: Introductionmentioning

confidence: 99%

Structure‐Property Relationships of Linear and Long‐Chain Branched Metallocene High‐Density Polyethylenes Characterized by Shear Rheology and SEC‐MALLS

Piel

Stadler

Kaschta

et al. 2005

Macro Chemistry & Physics

131

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Summary: Linear and long‐chain branched high‐density polyethylenes with a molar mass $\overline M _{\rm w}$ between 1 700 and 1 150 000 g · mol−1 were synthesized using metallocene catalyst systems. Depending on the polymerization parameters the molar mass distribution reached values ranging from 2 to 12. The resins were characterized with various analytical methods. The branch detection took place via two independent methods, melt rheology and SEC‐MALLS. New relationships between catalyst structure, polymerization conditions, and the branching content of polyethylenes were established. Besides the branched materials strictly linear polymers are presented; for those no long‐chain branches were detected either by light scattering or by rheology. The viscosity function was observed to be strongly influenced by the molar mass distribution and the degree of long‐chain branching. The molar mass distribution was affected by the catalyst type and the polymerization conditions. A dependence of the melting point and the melting enthalpy on the molar mass was observed.

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“…The most commonly cited mechanism for LCB formation is macromonomer incorporation [346,347]. The vinyl end-group of one terminated chain becomes copolymerized into another growing chain.…”

Section: Long Chain Branchingmentioning

confidence: 99%

Review of the Phillips Chromium Catalyst for Ethylene Polymerization

McDaniel

2008

Handbook of Heterogeneous Catalysis

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The year 2001 marked the 50th anniversary of the discovery of the Phillips chromium catalyst, from which today's worldwide high‐density polyethylene industry sprang. Appropriately, during that year the discoverers of this catalyst system, J. Paul Hogan and Robert L. Banks, were inducted into the National Inventors Hall of Fame, in Akron, OH, to join other distinguished inventors spanning two centuries who have shaped our world. This chapter reviews our understanding of the chemistry associated with that catalyst system, which is used globally to produce perhaps half of the world's high‐density polyethylene, and it provides examples of how that chemistry is exploited commercially.

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Novel mechanism for the formation of long-chain branching in polyethylene

Cited by 35 publications

References 17 publications

Polyolefins with Long Chain Branches Made with Single‐Site Coordination Catalysts: A Review of Mathematical Modeling Techniques for Polymer Microstructure

Polyolefins with Long Chain Branches Made with Single‐Site Coordination Catalysts: A Review of Mathematical Modeling Techniques for Polymer Microstructure

Structure‐Property Relationships of Linear and Long‐Chain Branched Metallocene High‐Density Polyethylenes Characterized by Shear Rheology and SEC‐MALLS

Review of the Phillips Chromium Catalyst for Ethylene Polymerization

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