Paper Number
SC29 

Session
Suspensions and Colloids

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

Presentation Date and Time
October 20, 2009 (Tuesday) 5:15

Track / Room
Track 1 / Lecture Hall

Authors (Click on name to view author profile)

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)

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

Speaker / Presenter 
Carreau, Pierre J.

Text of Abstract
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.