Improving temperature gradient interaction chromatography of polyolefins by simultaneous use of different stationary phases

Ndiripo, Anthony; Ndlovu, Petronella Zabesuthu; Albrecht, A. C.; Pasch, Harald

doi:10.1016/j.chroma.2021.462416

Cited by 5 publications

(3 citation statements)

References 21 publications

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“…We have recently demonstrated that these conditions give the best-known separation for polyolefins, at least with linear low-density polyethylenes (LLDPEs). 45 A stack plot of elugrams of the four LCBPEs, LDPE, and linear PE is presented in Figure 7 for three different IC-separations.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…In the first experiment, a solvent gradient comprising 1-dodecanol → TCB was used with a 300 mm PGC at 160 °C, as presented in Figure a. We have recently demonstrated that these conditions give the best-known separation for polyolefins, at least with linear low-density polyethylenes (LLDPEs) . A stack plot of elugrams of the four LCBPEs, LDPE, and linear PE is presented in Figure for three different IC-separations.…”

Section: Resultsmentioning

confidence: 99%

“…Here, only LDPE can be easily separated from the LCBPEs due to the contributions of SCB. We attribute the similar elution behavior of the LCBPEs to the strong indiscriminate interactive force of the PGC stationary phase under these conditions. , The peak fronting of the LCBPEs is also different, increasing with an increase in LCB. For future work, it would be interesting to couple such separations to a viscometry and light scattering detector to determine the LCB contents.…”

Section: Resultsmentioning

confidence: 99%

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Nonlinear Ziegler–Natta-Homopolyethylene with Enhanced Crystallinity: Physical and Macromolecular Characteristics

Ndlovu,

Ndiripo,

Albrecht

et al. 2024

Macromolecules

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Polyolefin engineering and design are at the forefront of a significant number of research and development laboratories, helping to bring about new and highly specific materials for tailored uses. Tailoring the chain architecture of polyolefins improves their performance and physical properties. Four unique polyethylene (PE) materials with long-chain branches (LCBPE) are studied using advanced chromatographic fractionation techniques alongside linear high-density PE (HDPE) and typical commercial low-density PE (LDPE). The absence of short-chain branching in the analyzed LCBPEs allows for a defined correlation of long-chain branching (LCB) with specific physical properties. Possible effects of side-chain crystallization on melt behavior and crystallinity clearly show that the nonlinearity in architecture positively affects crystallinity while simultaneously lowering melting temperature. The separation of polyolefins according to the LCB content is demonstrated for the first time by high-temperature interaction chromatography and thermal analysis, in addition to size exclusion chromatography coupled to differential viscometer and light scattering detectors. This study is pioneering in applying solvent gradient interaction chromatography and stationary-phaseassisted crystallization to the separation of PE regarding long-chain branching.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Nonlinear Ziegler–Natta-Homopolyethylene with Enhanced Crystallinity: Physical and Macromolecular Characteristics

Ndlovu,

Ndiripo,

Albrecht

et al. 2024

Macromolecules

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Fractionation of Polymers

Lederer¹,

Ndiripo²

2023

Encyclopedia of Polymer Science and Technology

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Synthetic and natural polymers exist in microstructural distributions, such as chain length, size, chemical composition, branching, tacticity, or comonomer sequence distributions. Polymer fractionation techniques are essential for the analysis of these distributions and help in understanding polymerization mechanisms and material properties. In this article, the theoretical basics of general fractionation approaches and specific fractionation techniques are discussed. Details are given on fractionation techniques for molar mass and chemical composition distribution analysis, such as temperature rising elution fractionation (TREF), crystallization analysis fractionation (CRYSTAF), or crystallization elution fractionation (CEF). In addition, column‐based and channel‐based fractionation methods are extensively discussed. Theoretical and practical aspects of the analysis of molar mass distributions using size exclusion chromatography (SEC) as well as chemical composition distributions by interaction chromatography (SGIC, TGIC, LCCC) and multidimensional separations (2D‐LC) are reviewed and compared. General aspects and details on asymmetrical flow and thermal field flow fractionation techniques (AF4 and ThFFF) are discussed and examples of suitable physical and chemical detectors coupled to fractionation devices for the analysis of size, conformation, or chemical composition and topology are demonstrated.

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Principles and applications of porous graphitic carbon stationary phase in liquid chromatography: An update

Russo,

Camillo,

La Tella

et al. 2024

Journal of Chromatography A

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Improving temperature gradient interaction chromatography of polyolefins by simultaneous use of different stationary phases

Cited by 5 publications

References 21 publications

Nonlinear Ziegler–Natta-Homopolyethylene with Enhanced Crystallinity: Physical and Macromolecular Characteristics

Nonlinear Ziegler–Natta-Homopolyethylene with Enhanced Crystallinity: Physical and Macromolecular Characteristics

Fractionation of Polymers

Principles and applications of porous graphitic carbon stationary phase in liquid chromatography: An update

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