取向碳纳米管纤维力学增强及微结构/力学性能关系研究

Recently, the fabrication of aligned carbon nanotube fibers (aligned CNT fibers) has opened the door for the real application of CNTs in high performance composites. However, the mechanical properties of the aligned CNT fibers are currently inferior to these of commercial high performance fibers, such as carbon fibers, glass fibers, aromatic fibers and so on, and fall far short of the mechanical properties of individual CNTs. On the other hand, the existing experimental tools still can't be applied to reveal the structure/property relations of aligned CNT fibers, which greatly hinds the optimization of the fiber mechanical properties. This research project aims to address these issues through both experimental and modeling efforts. To increase the fiber strength, the intertube load transfer efficiency in the aligned CNT fibers will be enhanced through stretching and densifying the fibers as well as improving the inteactions between CNT and polymers in the fibers. Meanwhile, large scale computational simulations will be performed to study the structural evolutions of aligned CNT fibers under loading, and to investigate their microstructure/mechanical property relations, as well as to understand the mechanism of aligned CNT fiber strengthening by polymer infiltation. This study will provide theoretical guidance for developing high performance aligned CNT fibers, and propel the development of light-weight, high performance, and multifunctional composites in China.

近年来，取向碳纳米管纤维的成功制备为碳纳米管在高性能复合材料中的应用带来了希望。目前，取向碳纳米管纤维的力学性能和传统的增强纤维（如碳纤维，玻璃纤维，芳纶纤维等）相比仍较低，而且远低于碳纳米管本身的力学性能。另外，现有的实验手段仍难以揭示取向碳纳米管纤维的微结构/力学性能关系，制约了人们对这一新材料力学性能的进一步优化。因此，本课题将通过牵伸和致密化取向碳纳米管纤维和改善碳纳米管/聚合物之间界面两种方法，来增强取向碳纳米管纤维内碳管之间力学性能的传递效率，提高取向碳纳米管纤维的力学性能。同时，我们将利用计算模拟手段研究取向碳纳米管纤维在载荷作用下的力学响应，探讨其微结构/力学性能关系，以及聚合物增强碳纳米管纤维的增强机理。本课题将为实验研制高性能取向碳纳米管纤维提供理论指导，推动我国轻质、高性能、多功能复合材料的发展。

将具有超高力学性能的碳纳米管取向组装成连续纤维是实现其在复合材料中高效应用的重要途径之一。由于碳纳米管纤维中碳管弯曲程度高，孔隙率高，使得其自身优异的力学性能无法在纤维中得到充分发挥。理解碳纳米管结构性能关系和开发碳纳米管纤维高性能化方法是实现其工程化应用的重要前提条件。为此，本课题开发了碳纳米管纤维牵伸、加捻、以及挤压等致密化方法，搭建一套纤维连续牵伸与加捻致密化设备，有效提升了纤维拉伸力学性能；通过在纤维空隙中引入半晶质聚乙烯醇分子，并结合热牵伸工艺，使得纤维强度达到约1.6 GPa；通过在纤维制备过程中，原位引入二维氧化石墨烯，石墨烯与碳纳米管间强的π-π相互作用，使得碳纳米管之间形成更好的连接，提升了碳纳米管纤维的力学性能，且经过高温热处理后，纤维拉伸强度进一步提高至2.1 GPa；通过高温高压处理，使得碳纳米管管间形成sp3键连接，提高了碳管管间的力学传递效率；通过计算模拟分析，研究了碳纳米管管间焊接、石墨烯杂化及其高温处理、以及聚合物分子等对碳纳米管管间性能传递的影响规律与机制。本课题揭示了碳纳米管纤维工艺/结构/性能关系，为实验研制高性能取向碳纳米管纤维提供了理论指导，有望推动高性能纤维及其轻质、高性能、多功能复合材料的发展。