Carbon nanotubes (CNTs) exhibit an excellent combination of mechanical and electrical properties. The high tensile strength and electrical conductivity of individual CNTs from both theoretical predictions and experimental tests make them of great interest for various potential applications, such as aerospace composites, lightweight conductors, smart materials, sensors and actuators. However, efforts to obtain large assemblies of aligned CNTs with high performance remain elusive. This is a result of the limitations in synthesis of aligned and high quality CNTs, and their effective packing assembly to ensure load transfer among them.In this work, I present novel methods to manufacture well-aligned CNT sheets from chemical vapor deposition (CVD) of vertically aligned (VA-)CNTs. Three different catalyst patterns are designed, and VA-CNTs are planerized to change their orientation and join them into continuous micro-architectured sheets. The CNT sheets packing density is increased by ten folds compared to their density from the synthesis process by using capillary forces. I studied a method for removing the CNT sheets from the growth substrate and protocols to test their tensile strength, tearing energy and electrical conductivity at different growth height. The highest tensile strength measured is 0.4 GPa and the average is 0.15 GPa for staggered CNT micro-architecture reminiscent of the brick and mortar morphology found in nature. The highest tearing energy measured is 11.6 kJ/m2 indicating the promise to use these materials in load bearing applications.
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Mechanical and electrical properties of micro-architectured carbon nanotube sheet
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