Uncovering the interface slipping and microplastic accumulation mechanism of carbon nanotube fibers under different temperatures

Understanding the microplastic accumulation behavior of advanced carbon nanotube (CNT) fibers under complex thermal conditions is crucial in aerospace structures' durability and safety design, and the intrinsic plastic mechanism of CNT fibers under high-temperature prospects further investigation from the theoretical to the experimental. Herein, a novel CNT-CNT interface model was developed to clarify the microplastic evolution mechanism and its temperature effect. A series of cyclic-loading experiments at different temperatures were investigated to uncover the plastic accumulation process of CNT fibers. The in-situ scanning electric microscopy (SEM) experiments were introduced to observe the microstructure evolution of the CNT fiber under cyclic loading. The CNT fibers show more serious plasticity and weaker high-temperature fatigue resistance. The distance and overlap length between CNTs dominate the evolution of materials' plastic and thermal behavior. It can be concluded that optimizing the arrangement of the microstructures and limiting the thermal expansion between tubes will improve the fatigue resistance of CNT fibers. This work could provide an in-depth description of microplastic mechanisms and better guidance for the aerospace application of high-performance fibers under complex loading environments.