Mechanical properties of carbon nanotube fibers at extreme temperatures†
Carbon nanotube (CNT) fibers are strong, flexible, and multifunctional, which makes them promising candidates for use at extreme temperatures. However, the current reported mechanical properties of CNT fibers were commonly obtained at room temperature. Here, we report the measurement of the mechanical properties of CNT fibers at temperatures ranging from −196 °C to 2400 °C. Compared with the room temperature strength and modulus, CNT fibers tested at 1000 °C and 2400 °C retained 82% and 54% of the strength, and 71% and 50% of the modulus, respectively, while 68% and 220% increases in the strength and modulus, respectively, were observed for CNT fibers tested at −196 °C. We attributed the decay in the mechanical properties at high temperatures to the weakening of individual nanotubes and intertube interactions, and the strength enhancement at low temperature to the increased activation energy to break the nanotubes. The present study provides the fundamental mechanical properties of CNT fibers at extreme temperatures, which could facilitate the applications of CNT fibers in aeronautics and astronautics where extreme temperature conditions commonly exist.