The Microstructure and Rheology of Carbon Nanotube Suspensions

Cherry Auditorium, Kirk Hall

Carbon nanotubes (CNTs) have a diameter on the nanometer scale and a length on the micrometer or even centimeter scale. The high aspect ratio of CNTs implies only a small CNT loading (typically < 0.1 wt%) is needed to achieve conductive pathways, offering a unique competitive advantage for using CNTs as conductive fillers for polymers. However, the very same feature of CNTs also poses a processing challenge. To this end, understanding the microstructure and rheology of CNTs dispersed within a polymer matrix is critical to processing CNTs into functional materials in a scalable and controllable manner. In the first part of the presentation, I will highlight our experimental observations and modeling of the rheology of two different classes of CNTs: (1) CNTs that aggregate and (2) CNTs that do not aggregate in flow. The shear and extensional flow behavior of these two classes of CNTs will be compared and contrasted. In the second part of the presentation, preliminary findings on the microstructure and rheology of CNTs adsorbed at an air-water interface will be presented. The findings may have implications on the development of more stable emulsions and the production of CNT thin films with controllable packing density and orientational ordering.