Metallic carbon nanotube yarn - on path to surpassing copper
The conductivity and strength of industrial-scale carbon nanotube (CNTs) fiber incrementally continue to increase. Currently, their mechanical strength equals high-quality commercial carbon fiber with over ten times the conductivity-- making them the best material currently available for the multiplicative product, conductivity x strength. Much of the development of bulk CNT materials mirror the development of older carbon-based conductors, graphitic intercalation compounds (GICs) and conductive polymers such as iodine doped polyacetylene (iPaC). Long ago GiCs have exceeded, and iPaC has approached, the conductivity of copper. Carbon nanotubes have not yet reached these high conductivity values. In this talk we review the state of the art of CNT fibers, their extrinsic attributes, and intrinsic transport characteristics that lead to high conductivities potentially superior to GiCs and iPaC. We will show recent results with production of twisted CNT yarn hundreds of meters long with signatures of predominantly metallic electronic structure. We will showcase a super-acid postprocess which uniquely interacts with this "metallic" CNT yarn and aligns its microstructure when stretched.