A major breakthrough in the research of ultra-strong carbon nanotube fibers in China
Recently, the team of Professor Wei Fei of the Department of Chemical Engineering of Tsinghua University teamed up with Prof. Li Xide of the School of Aeronautics and Astronautics of Tsinghua University to make a major breakthrough in the field of super-long carbon nanotube fibers. It was reported for the first time in the world that the theoretical strength of single carbon nanotubes was extremely long. Carbon nanotube bundles have a tensile strength that exceeds all other fiber materials currently found.
Carbon nanotubes are considered to be one of the most powerful materials currently found, with tensile strengths of more than 100 GPa and more than 10 carbon fiber strengths. However, when a single carbon nanotube with excellent mechanical properties is prepared into a macroscopic material, its performance is often far below the theoretical value. In contrast, ultra-long carbon nanotubes have centimeters or even decimeters in length and have a perfect structure, with uniform orientation and mechanical properties close to the theoretical limit, and have great advantages in the preparation of super-strong fibers.
By using in-situ gas flow focusing methods, the research team can control the preparation of a centimeter continuous super-long carbon nanotube tube with a definite composition, a perfect structure and a parallel arrangement, and skillfully avoids the limiting factor. By preparing bundles of ultra-long carbon nanotubes containing different numbers of units and quantitatively analyzing the effects of their composition on the mechanical properties of bundles of ultra-long carbon nanotubes, established physical/mathematical models were established.
The study found that the initial stress distribution of the carbon nanotubes in the tube bundle is not uniform, so that the carbon nanotubes in the tube bundle cannot be subjected to simultaneous and uniform forces, which in turn leads to a decrease in the overall strength, that is, the “Daniel effect”. Based on this, the research team proposed a “synchronous relaxation” strategy, which releases the initial stress of the carbon nanotubes in the tube bundle by nanomanipulation, so that it is in a narrow range of distribution, and thus the carbon nanotube beam tensile strength Raised to above 80 GPa, close to the tensile strength of single carbon nanotubes.
This work reveals the bright prospects of using ultra-long carbon nanotubes for the manufacture of superfibers, and at the same time points out the directions and methods for the development of new superfibers.