Transient flow responses of carbon nanotubes suspensions after a shear reversal

Abstract

In this study, we have investigated the fluidity responses after a shear flow reversal of carbon nanotube (CNT) suspensions with Newtonian carrier liquids in stress-sweep tests. The suspensions have showed transient decrease in viscosity, i.e., increase in fluidity, after the flow reversal in shearing direction. Moreover, i.e. transient shear thickening phenomena, in viscosity were observed at a certain shear rate. In order to quantitatively clarify the viscosity recovery, a typical strain γp corresponding to the peak of viscosity recovery was estimated. Independence of γp from stress sweep-rates applied was shown for respective suspensions. Moreover, dependence of viscosity of the carrier liquid and volume fraction of CNT was also examined. I n the result, it is clarified that lower γp was obtained with light carrier liquids and high volume fraction. It is considered that these results will be correlated to the change in flowing structure of CNTs depending on the shear rate applied.

Keywords

• complex fluid
• non-newtonian fluid
• carbon nanotube
• suspension
• shear flow