Abstract As an effective method to tune the strength and ductility of carbon nanotube (CNT) assembles, twist is very important for high performance CNT-based artificial muscles and actuators. During the twisting, the microstructural evolution and the accompanying strengthening effect would play key roles in determining the final functionalities of storage and release of mechanical energy. Toward the future development of twist-based CNT devices, especially by using CNT ribbons, it is of great necessity to understand the underlying twist-induced mechanical behavior. Here, based on an in-situ microscopic test, we report the origination of twist-enhanced ductility and the stiffened interfacial interconnection between CNTs caused by polymer infiltration. The distribution of stored mechanical energy in twisted ribbons is determined by the twist degree and strongly dependent on various boundary conditions. The fixed boundary results in a lower surface angle, higher interior stress and energy, and more packing density than those of the free boundary during the twisting process. The surface angle gradually decreases during the stretching process. The higher interface friction force inclines to increase the stability of the microstructure evolution. This study can cast light on developing high-efficiency CNT-based actuation devices.

中文翻译：

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在界面和边界条件的影响下揭示扭转碳纳米管带的机械强化机制

摘要 作为调节碳纳米管（CNT）组合强度和延展性的有效方法，扭曲对于高性能的基于碳纳米管的人造肌肉和执行器非常重要。在扭转过程中，微观结构演变和随之而来的强化效应将在决定机械能储存和释放的最终功能方面发挥关键作用。对于基于扭曲的 CNT 器件的未来发展，特别是通过使用 CNT 带，非常有必要了解潜在的扭曲引起的机械行为。在这里，基于原位显微测试，我们报告了扭曲增强延展性的起源和由聚合物渗透引起的 CNT 之间加强的界面互连。扭曲带中储存的机械能的分布由扭曲程度决定，并且强烈依赖于各种边界条件。在扭曲过程中，固定边界比自由边界产生更低的表面角度、更高的内应力和能量以及更高的堆积密度。在拉伸过程中表面角度逐渐减小。较高的界面摩擦力倾向于增加微观结构演化的稳定性。这项研究可以为开发高效的基于碳纳米管的驱动装置提供启示。在拉伸过程中表面角度逐渐减小。较高的界面摩擦力倾向于增加微观结构演化的稳定性。这项研究可以为开发高效的基于碳纳米管的驱动装置提供启示。在拉伸过程中表面角度逐渐减小。较高的界面摩擦力倾向于增加微观结构演化的稳定性。这项研究可以为开发高效的基于碳纳米管的驱动装置提供启示。