Glasslike transitions in thin polymer-melt films due to thickness constraint

Shinji Yamada, Gen Ichi Nakamura, Yoko Hanada, Takayuki Amiya

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The shear properties of thin films of star and linear polyisoprene (PIP) melts under high pressure were investigated as a function of sliding velocity (shear rate) using the surface forces apparatus. The results were contrasted with their bulk rheological properties; effects of thickness constraint on the shear behavior were discussed. The melts of PIP in bulk exhibit Newtonian-like constant viscosity at least at low shear rates (frequencies), which suggests that individual molecules flow with lateral sliding motion. However, thin films of PIP melts show tribological features involving apparent shear-thinning behavior, indicative of the correlated motions in confined geometries. The shear-property change from bulk rheological behavior to thin-film tribological behavior along with the thickness decrease reflects the physical states and their transitions in the systems; the thickness constraint induces glasslike transitions. Effects of molecular weights and molecular architecture (star-branched or linear) on the shear properties are also discussed.

Original languageEnglish
Pages (from-to)83-89
Number of pages7
JournalTribology Letters
Volume15
Issue number2
DOIs
Publication statusPublished - 2003 Aug 1

Keywords

  • Glasslike transition
  • Nanorheology thickness constraint
  • Nanotribology
  • Surface forces apparatus
  • Thin polymer-melt films

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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