Nonlinear time-dependent response of polypropylene/nanoclay melts: Experiments and modeling

A. D. Drozdov, E. A. Jensen, J. de C. Christiansen

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Observations are reported on polypropylene/compatibilizer/nanoclay hybrid melts with a fixed clay/compatibilizer proportion 1:2 and various concentrations of filler (from 0 to 5 wt.%) in start-up shear tests with a constant strain rate and relaxation tests at various strains (in the interval of shears between 1 and 20). It is shown that growth of nanoclay content leads to formation of stress overshoot in start-up tests and slowing down of the relaxation process (which is strongly affected by strain). A constitutive model is derived for the time-dependent response of nanocomposite melts under three-dimensional deformations with finite strains, and its adjustable parameters are found by fitting the experimental data. It is demonstrated that some critical concentration of nanoclay exists (about 1 wt.%), at which the mean activation energy for rearrangement of chains and its standard deviation are minimal. The presence of a threshold concentration of filler is confirmed by observations in uniaxial tensile tests on solid nanocomposites.

Original languageEnglish
Pages (from-to)807-816
Number of pages10
JournalComputational Materials Science
Volume47
Issue number3
DOIs
StatePublished - 1 Jan 2010
Externally publishedYes

Keywords

  • Constitutive modeling
  • Hybrid nanocomposites
  • Rheology
  • Viscoelasticity
  • Viscoplasticity

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