The Rheology and Microstructure of Carbon Nanotube (CNT) Suspensions

Abstract

This conference paper is concerned with the rheology and microstructure of Carbon Nanotube suspensions. Carbon Nanotubes (CNTs) are cylinders of rolled graphene sheets of high aspect ratio and they belong to a relatively new class of fibrous material that can potentially be used for high‐performance nano‐composites and nano‐devices. For these applications, understanding the rheology and microstructure of CNT suspensions is of key importance as this would allow for processing CNTs into macroscopically usable form with controlled properties. This paper reports the rheology and optical microstructure of surface‐treated and untreated CNT suspensions. In terms of rheology, both types of CNT suspensions exhibited a shear‐thinning characteristic in steady simple shear flows and their rheological responses were subsequently modelled using a Fokker‐Planck (FP) based orientation model that incorporates aggregation effect in the case of untreated CNT suspension. In terms of unusual mesostructures, it was observed that by applying appropriate flow conditions to an untreated CNT suspension, a novel type of mesoscopic filament structure could be formed, where the CNT filaments aligned perpendicular to the flow direction and in the vorticity direction. The formation of these anisotropic structures has similarities to the hand‐spinning of cotton into fibres and these flow‐induced structures might have strategic benefits for some potential applications of CNT.