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

0532374 - ÚMCH 2021 RIV DE eng J - Journal Article
Bucknall, C. - Altstädt, V. - Auhl, D. - Buckley, P. - Dijkstra, D. - Galeski, A. - Gögelein, C. - Handge, U. A. - He, J. - Liu, C.-Y. - Michler, G. - Piorkowska, E. - Šlouf, Miroslav - Vittorias, I. - Wu, J. J.
Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 1: characterizing molecular weight.
Pure and Applied Chemistry. Roč. 92, č. 9 (2020), s. 1469-1483. ISSN 0033-4545. E-ISSN 1365-3075
Institutional support: RVO:61389013
Keywords : high temperature creep * intrinsic viscosity * IUPAC Polymer Division
OECD category: Polymer science
Impact factor: 2.453, year: 2020
Method of publishing: Open access
https://www.degruyter.com/view/journals/pac/92/9/article-p1469.xml?tab_body=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 ̅Mw 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 ̅Mw, 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.
Permanent Link: http://hdl.handle.net/11104/0311629