Abstract:Unique macrostructures known as spun carbon-nanotube fibers (CNT yarns) can be manufactured from vertically aligned forests of multi-walled carbon nanotubes (MWCNTs). These yarns behave as semiconductors with room-temperature conductivities of about 5x10 2 S cm -1 . Their potential use as, for example, microelectrodes in medical implants, wires in microelectronics, or lightweight conductors in the aviation industry has hitherto been hampered by their insufficient electrical conductivity. In this Full Paper, the synthesis of metal-CNT composite yarns, which combine the unique properties of CNT yarns and nanocrystalline metals to obtain a new class of materials with enhanced electrical conductivity, is presented. The synthesis is achieved using a new technique, self-fuelled electro deposition (SFED), which combines a metal reducing agent and an external circuit for transfer of electrons to the CNT surface, where the deposition of metal nano-particles takes place. In particular, the Cu-CNT and Au-CNT composite yarns prepared by this method have metallike electrical conductivities (2-3 x 10 5 S cm -1 ) and are mechanically robust against stringent tape tests. However, the tensile strengths of the composite yarns are 30-50% smaller than that of the unmodified CNT yarn. The SFED technique described here can also be used as a convenient means for the deposition of metal nano-particles on solid electrode supports, such as conducting glass or carbon black, for catalytic applications.

Abstract.A modified process for the dry spinning of carbon nanotube (CNT) yarn is reported. The approach gives an improved structure of CNT bundles in the web drawn from the CNT forest and in the yarn produced from the twisted web leading to improved mechanical properties of the yarn. The process enables many different mechanical and physical treatments to be applied to the individual stages of the pure CNT spinning system, and may allow potential for the development of complex spinning processes such as polymer-CNT based composite yarns. The tensile strength and yarn/web structure of yarn spun using this approach have been investigated and evaluated using standard tensile testing methods along with scanning electron microscopy. The experimental results show that the tensile properties were significantly improved. The effect of heat treatments and other yarn constructions on the tensile properties are also reported.