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Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 2: crystallinity and supra molecular structure
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SYSNO ASEP 0532375 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 2: crystallinity and supra molecular structure Author(s) Bucknall, C. (GB)
Altstädt, V. (DE)
Auhl, D. (DE)
Buckley, P. (GB)
Dijkstra, D. (DE)
Galeski, A. (PL)
Gögelein, C. (DE)
Handge, U. A. (DE)
He, J. (CN)
Liu, C.-Y. (CN)
Michler, G. (DE)
Piorkowska, E. (PL)
Šlouf, Miroslav (UMCH-V) RID, ORCID
Vittorias, I. (CH)
Wu, J. J. (GB)Source Title Pure and Applied Chemistry. - : Walter de Gruyter - ISSN 0033-4545
Roč. 92, č. 9 (2020), s. 1485-1501Number of pages 17 s. Language eng - English Country DE - Germany Keywords crystallinity ; entanglements of macromolecules ; fusion defects Subject RIV CD - Macromolecular Chemistry OECD category Polymer science Method of publishing Open access Institutional support UMCH-V - RVO:61389013 UT WOS 000574259400003 DOI 10.1515/pac-2019-0403 Annotation Test methods including OM, SEM, TEM, DSC, SAXS, WAXS, and IR were used to characterise supra-molecular structure in three batches of polyethylene (PE), which had weight-average relative molar masses Mw of approximately 0.6 × 106, 5 × 106, and 9 × 106. They were applied to compression mouldings made by the polymer manufacturer. Electron microscopy showed that powders formed in the polymerization reactor consisted of irregularly shaped grains between 50 and 250 μm in diameter. Higher magnification revealed that each grain was an aggregate, composed of particles between 0.4 and 0.8 μm in diameter, which were connected by long, thin fibrils. In compression mouldings, lamellar thicknesses ranged from 7 to 23 nm. Crystallinity varied between 70 and 75 % in reactor powder, but was lower in compression mouldings. Melting peak temperatures ranged from 138 to 145 °C, depending on processing history. DMTA showed that the glass transition temperature θ g was −120 °C for all three grades of polyethylene. IR spectroscopy found negligibly small levels of oxidation and thermal degradation in mouldings. Optical microscopy revealed the presence of visible fusion defects at grain boundaries. It is concluded that relatively weak defects can be characterized using optical microscopy, but there is a need for improved methods that can detect less obvious fusion defects. Workplace Institute of Macromolecular Chemistry Contact Eva Čechová, cechova@imc.cas.cz ; Tel.: 296 809 358 Year of Publishing 2021 Electronic address https://www.degruyter.com/view/journals/pac/92/9/article-p1485.xml?tab_body=abstract
Number of the records: 1