Nanotube Superfiber Materials

Nanotube Superfiber Materials: Science, Manufacturing, Commercialization, Second Edition, helps engineers and entrepreneurs understand the science behind the unique properties of nanotube fiber materials, how to efficiency and safely produce them, and how to transition them into commercial products. Each chapter gives an account of the basic science, manufacturing, properties and commercial potential of a specific nanotube material form and its application. New discoveries and technologies are explained, along with experiences in handing-off the improved materials to industry. This book spans nano-science, nano-manufacturing, and the commercialization of nanotube superfiber materials. As such, it opens up the vast commercial potential of nanotube superfiber materials. Applications for nanotube superfiber materials cut across most of the fields of engineering, including spacecraft, automobiles, drones, hyperloop tracks, water and air filters, infrastructure, wind energy, composites, and medicine where nanotube materials enable development of tiny machines that can work inside our bodies to diagnose and treat disease. Provides up to date information on the applications of nanotube fiber materials Explores both the manufacturing and commercialization of nanotube superfibers Sets out the processes for producing macro-scale materials from carbon nanotubes Describes the unique properties of these materials

Individual carbon nanotubes (CNTs) have exceptional mechanical and electrical properties. However, the transfer of these extraordinary qualities into CNT products, without compromising performance, remains a challenge. This chapter presents an overview of the manufacturing of CNT sheets and buckypaper and also describes research performed at the University of Cincinnati in this field. CNT arrays were grown using the chemical vapor deposition method. Sheets were drawn from the spinnable CNT arrays and characterized using scanning electron microscopy to show the highly unidirectional alignment of the nanotubes in the sheet. The anisotropic morphology of the sheet provides superior properties along one material axis as observed by measuring the tensile strength, electrical resistivity, optical transmittance, and electromagnetic interference shielding properties of the material. Surface modification of aligned multiwall nanotube sheets was carried out via incorporation of an atmospheric pressure plasma jet in the sheet posttreatment process. Helium/oxygen plasma was utilized to produce carboxyl (–COO−) functionality on the surface of the nanotubes. X-ray photoelectron spectroscopy confirmed the presence of the functional groups on the nanotube surface. The sheet was further characterized using Raman spectroscopy, Fourier transform infrared spectroscopy, and contact angle testing. Composite laminates made from functionalized CNT sheets showed higher strength than those made with pristine sheets. The effects of plasma power and oxygen concentration were studied in order to determine the best possible parameters for functionalization. Plasma treatment is a useful tool for fast, clean and dry functionalization of CNTs. This study demonstrates the ease of incorporating the plasma tool in the manufacturing process of sheets leading to the production of CNT/polymer composites. Macroscopic structures of nanotubes such as threads and sheets are leading to novel applications.

The nature of fiber materials and the differences between conventional fibers and nanoscale fibers are discussed in this chapter. The challenge of carbon nanotube (CNT) yarn fiber fabrication is provided from the perspective of conventional yarn fiber fabrication. Prospects for large-scale manufacturing and the physical properties of yarn are also discussed. This chapter sets the stage for presentation of a compendium of techniques working toward producing superfiber materials.

Nanotubes are a unique class of materials because their properties depend not only on their composition but also on their geometry. The diameter, number of walls, length, chirality, van der Waals forces, and quality all affect the properties and performance of nanotubes. This dependence on geometry is what makes scaling-up nanotubes to form bulk material so challenging. Nanotubes are also unusual because they stick together to form bundles or strands. Nanotube superfiber materials are fibrous assemblages of nanotubes and strands. The hope and dream of researchers around the world is that nanotube superfiber materials will have broad applications and change engineering design. This chapter gives a perspective on nanotube superfiber development. This chapter discusses new applications—where we think we can go with the material properties and what applications will be enabled—and new techniques for developing superfiber material.

In this chapter, the mechanics of nanotubes, graphene and related fibers are reviewed, with an eye to the limiting case of the design of a space elevator megacable. The effect on the fracture strength of thermodynamically unavoidable atomistic defects with different sizes and shapes is quantified. Brittle fracture is investigated both numerically (with ad hoc hierarchical simulations) and theoretically (with quantized fracture theories) for nanotubes, graphene and related bundles.

Individual carbon nanotubes (CNTs) have been reported to have the highest thermal conductivities of any known material. However, significant variability exists both for the reported thermal conductivities of individual CNTs and the thermal conductivities measured for macroscopic CNT assemblies (e.g. CNT films, buckypapers, arrays, and fibers), which range from comparable to metals to aerogel-like. This chapter reviews the current status of the field, summarizing a wide selection of experimental results and drawing conclusions regarding present limitations of the thermal conductivity of CNT assemblies and opportunities for improvement of the performance of nanotube superfiber materials.

Performance and efficiency demands in industrial applications are pushing a need for carbon fibers that can outperform existing technologies. Fibers that incorporate carbon nanotubes (CNTs) to enhance specific mechanical properties are a promising route to addressing this need. Some of the major roadblocks to unlocking the full potential of macroscopic fibers based on CNTs are controlling and optimizing the shear interactions within and between CNTs, geometrical organization of the CNTs, and structural properties of the individual CNTs. Several approaches have been pursued in order to optimize the mechanical behavior of CNT fibers, including irradiation-induced covalent cross-linking, reformable or rehealable bonding, and optimized geometrical and structural fiber designs. These approaches are inspired by nature, which uses hierarchical bonding schemes in optimized orientations to tailor the mechanical properties of its materials to the needs and environment of specific organisms. In this chapter, these approaches for developing high-performance CNT fibers will be reviewed, and an outlook of their potential impact will be discussed.

This chapter provides a systematic comparison of band structures, physical properties as well as associated applications between carbon nanotubes and graphene. Both these two carbon-based nanomaterials are composed of hexagonally arranged carbon atoms based on sp2 hybridization and thus share some relevant characteristics. However, they have significantly different electronic states due to their morphological variation in quantum confinement, which is responsible for their different electrical, mechanical, and optical properties. This chapter provides readers some basic knowledge, hints, and insights for choosing appropriate carbon-based nanomaterials for specific applications in electronics, machines, composites, optics, optoelectronics, and other areas.