Carbon nanotubes (CNTs) with light weight, ultrahigh strength, ultrahigh modulus, excellent electrical and thermal properties, have been considered as promising building blocks for constructing high-performance and multifunctional fibers for applications in both quasi-static and dynamic environments. However, the quasi-static and dynamic mechanical properties of CNT fibers (CNTFs) are limited by the poor interfacial interactions, low nanotube alignment, and high porosity formed in the spinning process.
On June 21, 2024, Professor Jin Zhang from the College of Chemistry and Molecular Engineering, School of Materials Science and Engineering at Peking University, and Beijing Graphene Institute, cooperated with Associate Professor Muqiang Jian from Beijing Graphene Institute, Professor Xianqian Wu from Institute of Mechanics, Chinese Academy of Sciences, Associate Professor Enlai Gao from Wuhan University, and Professor Yongyi Zhang from Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, University of Science and Technology of China, and Jiangxi Institute of Nanotechnology, published a research article entitled “Carbon nanotube fibers with dynamic strength up to 14 GPa” in Science. This study reported a strategy that included progressive stretching, infusion with poly(p-phenylene-2,6-benzobisoxazole) (PBO) nanofibers and molecular chains, and mechanical rolling to improve the interfacial interactions, nanotube alignment, and densification of CNTFs. The resultant fibers exhibited a dynamic strength of 14.0 GPa under a high strain rate of about 1400 s–1, values that are higher than those of commercial fibers.
Fig. 1 Preparation, morphology, and mechanical properties of CNTFs. (A) Strategy to develop highly packed and well-aligned CNTFs. (B) Digital photograph of PBO-CNTF tows. (C) Three-dimensionally reconstructed void microstructure (right) derived from nano-CT results (left) for D-PBO-CNTFs. (D) SEM (left and middle) and TEM (right) images of the radial cross section of D-PBO-CNTF cut by a focused ion beam. (E) Radar chart for comparing the mechanical performance of different CNTFs and commercial fibers.
The authors investigated the high-strain rate performance of fibers using a mini-split Hopkinson tension bar. The fracture morphologies of fibers showed that the intertube slippage of CNTFs at the high strain rates was inhibited, and the modified fibers exhibited a ductile-to-brittle transition in the fracture mode with increasing strain rates. The dynamic strength of fibers at a strain rate of about 1400 s–1 was 14 GPa，and substantially surpassed those of all other high-performance fibers, demonstrating that CNTFs have great promising applications in impact-resistant fields. Multiscale analyses combined with experimental evidence revealed that this strategy leads to improvements in interfacial interactions, nanotube alignment, and densification within the fibers, and the dynamic performance of CNTFs is primarily due to the simultaneous breakage of individual nanotubes and the exceptional impact-energy delocalization that occurs during the high-strain rate loading process.
Fig. 2 Mechanical properties of CNTFs. (A) Quasi-static stress-strain curves of CNTFs. (B) Comparison of quasi-static tensile strength, Young’s modulus, and toughness of different CNTFs. (C) Comparison of specific energy absorption and longitudinal wave velocity of fibers and other high-performance fibers. (D) Stress-strain curves of CNTFs at high strain rates of about 1400 s–1. (E) Comparison of the strength of CNTFs at different strain rates. (F) Comparison of the dynamic strength of our fibers and other high-performance fibers at high strain rates. (G) Comparison of the dynamic toughness of CNTFs at different strain rates. (H) Schematic diagram of laser-induced high-velocity transverse impact on a single fiber. (I) SEDP values of different fibers.
Dr. Xinshi Zhang (a Postdoctoral fellow) from the College of Chemistry and Molecular Engineering, Peking University, and Beijing Graphene Institute, Dr. Xudong Lei (a Postdoctoral fellow) from Institute of Mechanics, Chinese Academy of Sciences, and Xiangzheng Jia (a Ph.D. graduate) from Wuhan University are co-first authors of the article. The research was supported by the Ministry of Science and Technology of China, the National Natural Science Foundation of China, Beijing Natural Science Foundation and the Beijing National Laboratory for Molecular Sciences.
Link to the original article: https://www.science.org/doi/10.1126/science.adj1082.
