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Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 1: characterizing molecular weight

Authors
  • Bucknall, Clive1
  • Altstädt, Volker2
  • Auhl, Dietmar3
  • Buckley, Paul4
  • Dijkstra, Dirk5
  • Galeski, Andrzej6
  • Gögelein, Christoph7
  • Handge, Ulrich A.8
  • He, Jiasong9
  • Liu, Chen-Yang9
  • Michler, Goerg10
  • Piorkowska, Ewa6
  • Slouf, Miroslav11
  • Vittorias, Iakovos12
  • Wu, Jun Jie13
  • 1 Cranfield University, MK43 0AL , (United Kingdom)
  • 2 Universität Bayreuth, Germany , (Germany)
  • 3 Fakultät III - Werkstoffwissenschaft Technische Universität Berlin, D-10623 , (Germany)
  • 4 University of Oxford, OX1 3PJ , (United Kingdom)
  • 5 Covestro Deutschland AG, Germany , (Germany)
  • 6 Polish Academy of Sciences, Poland , (Poland)
  • 7 Arlanxeo Deutschland GmbH, Germany , (Germany)
  • 8 Helmholtz-Zentrum Geesthacht, Max-Planck-Strasse 1, 21502 , (Germany)
  • 9 Laboratory of Polymer Science and Materials, 100190 , (China)
  • 10 Martin-Luther-Universität Halle-Wittenberg, Germany , (Germany)
  • 11 Institute of Macromolecular Chemistry CAS, Czech Republic , (Czechia)
  • 12 Omya International AG, Baslerstrasse 42, CH-4665 , (Switzerland)
  • 13 Durham University, Stockton Road, DH1 3LE , (United Kingdom)
Type
Published Article
Journal
Pure and Applied Chemistry
Publisher
Walter de Gruyter GmbH
Publication Date
Aug 24, 2020
Volume
92
Issue
9
Pages
1469–1483
Identifiers
DOI: 10.1515/pac-2019-0405
Source
De Gruyter
Keywords
License
Yellow

Abstract

The aim of this project was to study the efficacy of current methods of quality control and quality assurance for ultra-high molecular weight polyethylene (UHMWPE) products, and find improvements where possible. Intrinsic viscosity (IV) tests were performed on three grades of polyethylene with weight average relative molar masses M ̅ $̅{M}$ w of about 6 × 105, 5.0 × 106 and 9.0 × 106. Results from three laboratories showed substantial scatter, probably because different methods were used to make and test solutions. Tensile tests were carried out to 600 % extension at 150 °C under both constant applied load and constant Hencky strain rate, on compression mouldings made by a leading manufacturer of ultra-high molecular weight polyethylene. They gave low values of M ̅ $̅{M}$ w, suggesting incomplete entanglement at ‘grain boundaries’ between powder particles. Results from conventional melt-rheology tests are presented, and their relevance to quality control and assurance is discussed. Attempts to calculate molecular weights from these data met with limited success because of extended relaxation times. Suggestions are made for improving international standards for IV testing of UHMWPE, by investigating the various factors that can cause significant errors, and by introducing methods for checking the homogeneity (and hence validity) of the solutions tested. Part 2 addresses characterization of crystallinity and structure. Part 3 covers mechanical properties, and Part 4 focuses on the sporadic crack propagation behaviour exhibited by all three grades of UHMWPE in fatigue tests on 10 mm thick compact tension specimens.

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