With a tensile strength exceeding 100 GPa, individual carbon nanotubes (CNTs) are among the strongest known materials. Realizing that ideal strength is challenging. When CNTs are fabricated in bulk, the end product is often a jumbled mass of tubes shorter than a few hundred micrometers in length and filled with structural defects and impurities. Those features reduce the nanotubes’ collective strength to a small fraction of the strength of an individual CNT.
Recently Fei Wei, Rufan Zhang, and their colleagues at China’s Tsinghua University developed a method to synthesize CNTs into bundles several centimeters long, with each containing up to 15 nearly defect-free CNTs. Despite the near-perfect crystalline growth, the researchers found that the CNTs in each bundle still differed in orientation and length. The larger the number of CNTs in a bundle, the further the bundle’s tensile strength fell below the ideal value. That’s because the load would be concentrated in just one or two CNTs instead of being evenly shared by them all.
Solving this problem would provide exactly what is needed to realize something like a 'space elevator.' To read more, click here.