Polypropylene-graphite nanocomposites made by solid-state shear pulverization: Effects of significantly exfoliated, unmodified graphite content on physical, mechanical and electrical properties

Katsuyuki Wakabayashi, Philip J. Brunner, Jun'ichi Masuda, Sheldon A. Hewlett, John M. Torkelson*

*Corresponding author for this work

Research output: Contribution to journalArticle

93 Scopus citations

Abstract

Nanocomposites made from polypropylene and as-received graphite were prepared by solid-state shear pulverization (SSSP) as a function of graphite loading (0.3-8.4 wt%). X-ray diffraction indicates that SSSP employing harsh pulverization conditions yields substantial graphite exfoliation at 0.3-2.7 wt% graphite content with less exfoliation being achieved at higher graphite content. With increasing graphite content, thermal degradation temperature and non-isothermal onset crystallization temperature increase substantially (by as much as 35 and 23 °C relative to neat polypropylene) while isothermal crystallization half-time decreases dramatically. In contrast, Young's modulus and tensile yield strength exhibit maxima (~100% and ~60% increases, respectively, relative to neat polypropylene) at 2.7 wt% graphite content, with all nanocomposites retaining high elongation at break values except at the highest filler loading. Electrical conductivity measurements indicate percolation of graphite at 2.7 wt% and higher graphite content, consistent with rheology measurements showing the presence of a solid-like response of melt-state shear storage modulus as a function of frequency. Significant tunability of graphite exfoliation and property enhancements is demonstrated as a function of SSSP processing.

Original languageEnglish (US)
Pages (from-to)5525-5531
Number of pages7
JournalPolymer
Volume51
Issue number23
DOIs
StatePublished - Oct 29 2010

Keywords

  • Graphite
  • Nanocomposites
  • Pulverization

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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