The Experts below are selected from a list of 25632 Experts worldwide ranked by ideXlab platform
Zhe Zhou - One of the best experts on this subject based on the ideXlab platform.
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nmr study of the separation mechanism of polyethylene octene block copolymer by ht lc with graphite
Macromolecules, 2015Co-Authors: Zhe Zhou, Matthew Mille, Dea Lee, Rongjua Cong, C Klinke, T Huang, Li Pi C Sha, Ill Winniford, Alexande W Degroo, Thomas W KarjalaAbstract:High temperature liquid chromatography (HT-LC) and temperature gradient interaction chromatography (TGIC) using a graphite substrate were recently invented to characterize Polyolefin microstructures and composition distributions. Their separation mechanisms have been explored by using a series of random copolymers. In addition, the separation mechanism of TGIC for random copolymers was also studied with a high temperature NMR cryoprobe. The proposed separation mechanism for a random copolymer is that the separation is likely based on comonomer content, in other words, the number-averaged ethylene sequence length. Further understanding of HT-LC separation mechanism with polyethylene–octene block copolymers is beneficial in order to extend the use of HT-LC and TGIC to a wider variety of Polyolefin materials, and to better characterize more challenging microstructures of new materials. With the high temperature NMR cryoprobe technology, it is possible to perform 13C NMR of Polyolefins with a few milligrams o...
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a new technique for characterizing comonomer distribution in Polyolefins high temperature thermal gradient interaction chromatography ht tgic
Macromolecules, 2011Co-Authors: Rongjuan Cong, Willem Degroot, Al Parrott, Wallace W Yau, Lonnie G Hazlitt, Ray Brown, Matthew Miller, Zhe ZhouAbstract:This paper documents a new Polyolefin characterization technique, high-temperature thermal gradient interaction chromatography (HT-TGIC or TGIC), to quantify comonomer distribution. A set of homogeneous ethylene−octene homopolymers are used with a commercially available column having a graphitic substrate (HYPERCARB) to demonstrate this technique’s applicability to fractionating Polyolefins. The separation mechanism appears to be based on the interaction of the Polyolefin chains with the graphite surface upon a temperature change in an isocratic solvent. The TGIC technique overcomes the key issues encountered in crystallization based techniques and in high-temperature liquid chromatography with a solvent gradient (HT-LC). Crystallization based techniques cover only a narrow analysis range of 0−9 mol % comonomer content and suffer from potential error in the analysis caused by cocrystallization effects. HT-LC is limited in its capability because of the limited choice in detectors available. Conversely, TGI...
Joao B P Soares - One of the best experts on this subject based on the ideXlab platform.
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effect of column type on Polyolefin fractionation by high temperature thermal gradient interaction chromatography
Macromolecular Symposia, 2015Co-Authors: Abdulaal Z Alkhazaal, Joao B P SoaresAbstract:Summary High-temperature thermal gradient interaction chromatography (HT-TGIC) can be used to measure the chemical composition distribution (CCD) of semi-crystalline and amorphous Polyolefins. HT-TGIC extends the range of Polyolefin chemical compositions that can be measured today with crystallization-based techniques. Hypercarb® columns packed with porous graphitic carbon are commonly used as the stationary phase in HT-TGIC fractionation. We used a set of ethylene/1-octene copolymers having different comonomer fractions (up to 25% of 1-octene) and approximately the same molecular weight average to investigate how commercial Hypercarb® columns with distinct lengths and particle sizes affected HT-TGIC fractionation. Binary copolymer blends were also analyzed to study how different blend compositions affected HT-TGIC peak positions and shapes.
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Polyolefin Reaction Engineering
2012Co-Authors: Joao B P Soares, Timothy F. L. MckennaAbstract:PREFACE INTRODUCTION TO PolyolefinS Introduction Polyethylene Resins Polypropylene Resins Polyolefin MICROSTRUCTURAL CHARACTERIZATION Introduction Molecular Weight Distribution Chemical Composition Distribution Cross-Fractionation Techniques Long-Chain Branching POLYMERIZATION CATALYSIS AND MECHANISM Introduction Catalyst Types Supporting Single-Site Catalysts Polymerization Mechanism with Coordination Catalysts Polyolefin REACTORS AND PROCESSES Introduction Reactor Configurations and Design Olefin Polymerization Processes Conclusion POLYMERIZATION KINETICS Introduction Fundamental Model for Polymerization Kinetics Nonstandard Polymerization Kinetics Models Vapor-Liquid-Solid Equilibrium Considerations Polyolefin MICROSTRUCTURAL MODELING Introduction Instantaneous Distributions Monte Carlo Simulation PARTICLE GROWTH AND SINGLE PARTICLE MODELING Introduction Particle Fragmentation and Growth Single Particle Models Limitations of the PFM/MGM Approach: Particle Morphology DEVELOPING MODELS FOR INDUSTRIAL REACTORS Introduction
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Polyolefin Characterization: The First International Conference on Polyolefin Characterization - An Overview of Important Microstructural Distributions for Polyolefin Analysis
Macromolecular Symposia, 2007Co-Authors: Joao B P SoaresAbstract:Polyolefins with complex microstructures are becoming increasingly common in academic and industrial applications. Polyolefin analytical techniques are evolving to provide a more detailed picture of these microstructures, with the development and improvement of hyphenated-techniques and cross-fractionation methods. These modern analytical techniques provide a wealth of information on Polyolefin microstructure and, despite being extremely useful, they can also be hard to interpret without the help of mathematical models that link polymerization kinetics to chain microstructure and polymer characterization results. In this paper we review some of the most important distributions for Polyolefin microstructure and derive a few new expressions that help understand the results obtained with several Polyolefin characterization techniques.
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polymerization reaction engineering metallocene catalysts
Progress in Polymer Science, 1996Co-Authors: Archie E. Hamielec, Joao B P SoaresAbstract:Abstract Metallocene catalysts are operative in all existing industrial plants that are presently used for Polyolefin manufacture and have the potential to revolutionize the technology for the production of these polymers. A review of metallocene catalysis and its effects on polymer process engineering for the manufacture of Polyolefins is provided. This review concentrates on the aspects of polymer reactor engineering, mathematical modelling of polymerization processes, and the characterization of Polyolefins made with these novel catalysts.
Rongjuan Cong - One of the best experts on this subject based on the ideXlab platform.
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a new technique for characterizing comonomer distribution in Polyolefins high temperature thermal gradient interaction chromatography ht tgic
Macromolecules, 2011Co-Authors: Rongjuan Cong, Willem Degroot, Al Parrott, Wallace W Yau, Lonnie G Hazlitt, Ray Brown, Matthew Miller, Zhe ZhouAbstract:This paper documents a new Polyolefin characterization technique, high-temperature thermal gradient interaction chromatography (HT-TGIC or TGIC), to quantify comonomer distribution. A set of homogeneous ethylene−octene homopolymers are used with a commercially available column having a graphitic substrate (HYPERCARB) to demonstrate this technique’s applicability to fractionating Polyolefins. The separation mechanism appears to be based on the interaction of the Polyolefin chains with the graphite surface upon a temperature change in an isocratic solvent. The TGIC technique overcomes the key issues encountered in crystallization based techniques and in high-temperature liquid chromatography with a solvent gradient (HT-LC). Crystallization based techniques cover only a narrow analysis range of 0−9 mol % comonomer content and suffer from potential error in the analysis caused by cocrystallization effects. HT-LC is limited in its capability because of the limited choice in detectors available. Conversely, TGI...
Matthew Miller - One of the best experts on this subject based on the ideXlab platform.
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a new technique for characterizing comonomer distribution in Polyolefins high temperature thermal gradient interaction chromatography ht tgic
Macromolecules, 2011Co-Authors: Rongjuan Cong, Willem Degroot, Al Parrott, Wallace W Yau, Lonnie G Hazlitt, Ray Brown, Matthew Miller, Zhe ZhouAbstract:This paper documents a new Polyolefin characterization technique, high-temperature thermal gradient interaction chromatography (HT-TGIC or TGIC), to quantify comonomer distribution. A set of homogeneous ethylene−octene homopolymers are used with a commercially available column having a graphitic substrate (HYPERCARB) to demonstrate this technique’s applicability to fractionating Polyolefins. The separation mechanism appears to be based on the interaction of the Polyolefin chains with the graphite surface upon a temperature change in an isocratic solvent. The TGIC technique overcomes the key issues encountered in crystallization based techniques and in high-temperature liquid chromatography with a solvent gradient (HT-LC). Crystallization based techniques cover only a narrow analysis range of 0−9 mol % comonomer content and suffer from potential error in the analysis caused by cocrystallization effects. HT-LC is limited in its capability because of the limited choice in detectors available. Conversely, TGI...
Ray Brown - One of the best experts on this subject based on the ideXlab platform.
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a new technique for characterizing comonomer distribution in Polyolefins high temperature thermal gradient interaction chromatography ht tgic
Macromolecules, 2011Co-Authors: Rongjuan Cong, Willem Degroot, Al Parrott, Wallace W Yau, Lonnie G Hazlitt, Ray Brown, Matthew Miller, Zhe ZhouAbstract:This paper documents a new Polyolefin characterization technique, high-temperature thermal gradient interaction chromatography (HT-TGIC or TGIC), to quantify comonomer distribution. A set of homogeneous ethylene−octene homopolymers are used with a commercially available column having a graphitic substrate (HYPERCARB) to demonstrate this technique’s applicability to fractionating Polyolefins. The separation mechanism appears to be based on the interaction of the Polyolefin chains with the graphite surface upon a temperature change in an isocratic solvent. The TGIC technique overcomes the key issues encountered in crystallization based techniques and in high-temperature liquid chromatography with a solvent gradient (HT-LC). Crystallization based techniques cover only a narrow analysis range of 0−9 mol % comonomer content and suffer from potential error in the analysis caused by cocrystallization effects. HT-LC is limited in its capability because of the limited choice in detectors available. Conversely, TGI...