Paper Number
SC23 

Session
Suspensions and Colloids

Title
Rheo-optical response of carbon nanotube suspensions

Presentation Date and Time
October 7, 2014 (Tuesday) 2:20

Track / Room
Track 1 / Commonwealth A

Authors (Click on name to view author profile)

1. Natale, Giovanniantonio (École Polytechnique de Montréal, Chemical Engineering)
2. Reddy, Naveen K. (KU Leuven, Chemical Engineering)
3. Ausias, Gilles (Université de Bretagne du Sud, Mechanical Engineering)
4. Ferec, Julien (Université de Bretagne du Sud, Mechanical Engineering)
5. Heuzey, Marie-Claude (École Polytechnique de Montréal, Chemical Engineering)
6. Carreau, Pierre J. (École Polytechnique de Montréal, Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Giovanniantonio Natale¹, Naveen K. Reddy², Gilles Ausias³, Julien Ferec³, Marie-Claude Heuzey¹, and Pierre J. Carreau^1
1Chemical Engineering, École Polytechnique de Montréal, Montréal, Québec, Canada; ²Chemical Engineering, KU Leuven, Heverlee, Belgium; ³Mechanical Engineering, Université de Bretagne du Sud, Lorient, France

Speaker / Presenter 
Natale, Giovanniantonio

Text of Abstract
Carbon nanotubes (CNTs) hold remarkable promises for the next generation of materials, with potential applications in organic electronics, reinforced and electrically conducting composites and even new types of biological sensors and devices. Despite these potentialities, CNT suspensions in polymer melts are inherently difficult to process and in order to design efficient processing schemes, it is necessary to fully understand and predict their rheological behavior. In this work, we analyze the rheo-optical response of carbon nanotube suspensions, more specifically dichroism obtained in parallel plates and for the first time in a Couette flow geometry. CNTs were dispersed in a model Newtonian epoxy matrix, at different concentrations covering the dilute and semi-dilute regimes. Surprisingly, the average orientation angle with respect to the flow direction is far from zero degree even at high Péclet (Pe) numbers in very dilute suspensions. To explain this unique behavior, a new model for flexible rods, valid in the dilute regime, is proposed. It is based on the development proposed by Latz and Strautins (2007)¹ considering flexible rods made of beads and connectors. We modified their bending potential that allows only straight rods at equilibrium with a harmonic cosine expression. This simple modification changes drastically the behavior of these flexible particles that exhibits a non negligible orientation component in the vorticity direction, even under steady state.

1. Strautins U, Latz A. Flow-driven orientation dynamics of semiflexible fiber systems. Rheologica Acta. 2007/10/01 2007;46(8):1057-1064.