Pelletizing ultra-high molecular weight polyethylene (UHMWPE) powders with a novel tapered die and addition of high density polyethylene (HDPE): Processing, morphology, and properties

Huaguang Yang, Galip Yilmaz, Jing Jiang, Jun Xie, Thomas Langstraat, Raymond Chu, Martin van Es, Priya Garg, Lih Sheng Turng*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

7 Scopus citations

Abstract

The extremely high molecular weight and molecular entanglement have rendered ultra-high molecular weight polyethylene (UHMWPE) superior properties. However, poor inter-particle diffusion makes it difficult to pelletize UHMWPE powders for easy processing/handling. A novel tapered die with air cooling was proposed to pelletize UHMWPE and a UHMWPE blend with 5 wt% high-density polyethylene (HDPE) for compression molding and material characterization. The tensile strength of samples prepared with the tapered die outperformed those by the regular die or from virgin powders. The addition of HDPE further improved the tensile strength. Fourier transform infrared spectroscopy (FTIR) revealed little chain scission and the lowest amount of oxidation from the tapered die. Intrinsic viscosity (IV) measurements confirmed the negligible chain scission and showed an increment in IV for the UHMWPE/HDPE blend. Multi-angle light scattering with size-exclusion chromatography (SEC-MALS) indicated no change in the UHMWPE molecular weight distribution, but some crosslinking in the blend. Polarized optical microscopy (POM) showed that the HDPE and extrusion led to a finer UHMWPE domain size and better fusion between UHMWPE and HDPE. The combined effect of enhanced molecular chain diffusion, improved consolidation, and lower oxidation using the tapered die led to 40% improvement of tensile strength for the UHMWPE/HDPE blend.

Original languageEnglish
Article number125171
JournalPolymer
Volume256
DOIs
StatePublished - 21 09 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2022 Elsevier Ltd

Keywords

  • Pelletization
  • Tapered die
  • UHMWPE

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