SoR logo The Society of Rheology 81st Annual Meeting
October 18-22, 2009 - Madison, Wisconsin
View Paper Info and Abstract


Suspensions and Colloids

Rheological properties and percolation behavior of polypropylene/multiwalled carbon nanotube composites

October 20, 2009 (Tuesday) 5:15

Track 1 / Lecture Hall

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  1. Carreau, Pierre J. (Ecole Polytechnique, CREPEC, Chem. Eng. Dept.)
  2. Abbasi, Sameneh (Ecole Polytechnique, CREPEC, Chem. Eng. Dept.)
  3. Derdouri, Abdelsalim (National Research Council Canada, Industrial Materials Institute)

(in printed abstract book)
Pierre J. Carreau1, Sameneh Abbasi1, and Abdelsalim Derdouri2
1CREPEC, Chem. Eng. Dept., Ecole Polytechnique, Montreal, Quebec H3C3A7, Canada; 2Industrial Materials Institute, National Research Council Canada, Boucherville, Quebec JB4 6Y4, Canada

Carreau, Pierre J.

We present several issues related to the state of dispersion and rheological behavior of polypropylene/multiwalled carbon nanotube (MWCNT) composites. The composites were prepared by diluting a commercial masterbatch containing 20 wt % nanotubes using optimized melt-mixing conditions. The state of dispersion was then analyzed by scanning and transmission electron microscopy (SEM, TEM). To understand the percolated structure, the nanocomposites were characterized via a set of rheological and electrical conductivity measurements. No significant effect of the gap of the parallel plate geometry (or apparent slippage) was observed down to a 500 µm gap. G’ measurements were found to be temperature dependent; the percolation threshold was lower at higher temperature suggesting stronger nanotube interactions. The nanotube networks (characterized by G’) were also sensitive to the shear deformation, particularly at high temperature. The effect of shear deformation on the microstructure of the nanocomposites and nanotube networks was evaluated by subjecting each sample to different levels of shear stress for various periods of time. These results are further analyzed using simple models for suspensions of rod-like particles. Finally, the rheological and electrical conductivity percolation thresholds were compared. As expected the rheological threshold was found to be smaller than the electrical threshold: approximately equal to 0.2 and 0.5 wt % for the rheological and electrical conductivity measurements, respectively.