Studying Carbon Nanotubes on the Mesoscale: Physical Properties and Emergent Phenomena

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Since the first characterisation of carbon nanotubes (CNTs) by Iijima in 1991, a considerable amount of research has been conducted on their physical properties and applications. While CNTs as a material have shown promise, an inability to generate industrial quantities has limited their practical application. Among a variety of processes proposed to address this problem, the Floating Catalyst Chemical Vapour Deposition (FCCVD) process is of considerable academic and industrial interest for bulk CNT material production. The process produces dilute CNT network materials referred to as aerogels which can then be processed into continuous CNT fibres and composite materials. Developing an understanding of how aerogels and other CNT structure form during FCCVD and any subsequent process is critical in optimising the manufacturing process and tailoring material properties to specific applications.The aim of the PhD is to study the formation and physical properties of CNT structures using computational methods. In order to achieve suitable computation times, adaptive mesoscale methods are used which enable simulations of systems containing hundreds of millions of carbon atoms. These simulations can also be used to measure effective physical properties of the resulting material, such as mechanical resistance to load or electrical and thermal conductivities. Of particular interest are phenomena that emerge due to different microstructures rather than the properties of the individual CNTs. Examples are the transition from isolating to electrically conductive behaviour called electrical percolation as well as scaling of the electrical conductivity from individual CNTs to CNT fibres or bulk materials.