碳纳米管纤维的连续制备和强韧化机理研究

Because of their excellent mechanical, physical,and chemical properties, carbon nanotubes (CNTs) provide a new opportunity for developing fiber materials with both high strength, high toughness and structure-functionality integration. However, the properties of current CNT fibers fall far below theoretical predications, and the controllability of CNT structures, and the processability and fabrication continuity of CNT fibers need many improvements. In the present research, based on the approach of floating catalytic chemical vapor deposition, the technique for experimental control of CNT structures is investigated, and the principle and affecting factores of the self-assembling of CNTs to macroscopic fibers are studied. By optimizing the growth conditions and adjusting the spinning environment, continual fabrication is targeted for processable CNT fibers. Furthermore, the relationships between the mechanical properties and the nano-, micro- and macroscopic structures and morphologies of CNT fibers are researched. Focus is put on the effects of the tube diameter, length, alignment, intertube bonding, and fiber density on the load trasfer from tubes to the fiber. By controlling the in-situ growth, post mechanical processing and chemical modification, scientific approaches for improving the mechanical properties are investigated. This is to fully bring out the superiority of CNTs and realizing the strengthening and toughening of CNT fibers. The present research is of significant importance to the development of high-performance CNT fibers and their practical applications.

碳纳米管（CNT）由于具有优异的力学和理化性能,为开发高强高韧和结构-功能一体化碳纤维材料提供了新的选择。但目前CNT纤维的性能还与理论值存在一定的差距，CNT结构的可控性、CNT纤维的可加工性、制备的连续性，还需要改进。采用浮动CVD的方法，研究CNT结构可控生长的技术，研究其原位自组装形成宏观纤维的原理和控制因素。通过优化生长工艺和调整纺丝环境，实现可加工CNT纤维的连续制备。研究CNT纤维的力学性能与其纳米、微米和宏观尺度下的结构和形貌的关系，侧重于CNT直径、长度、定向性、管壁间的结合力和纤维本身的致密性对负载传递的影响规律；通过控制CNT的原位生长和CNT纤维的后续机械加工和化学改性，探索提高力学性能的科学途径，以便充分发挥CNT的优势，实现CNT纤维的强韧化。本研究对开发高性能CNT纤维及其大规模制备，促进其实际应用具有十分重要意义。

碳纳米管（CNT）由于具有优异的力学和理化性能,为开发高强高韧和结构-功能一体化纤维材料提供了新的选择。但目前CNT纤维的性能还与理论值存在很大的差距，CNT结构的可控性、CNT纤维的可加工性、制备的连续性，还需要较大的改进。采用浮动CVD的方法，研究CNT了结构可控生长的技术，研究其原位自组装形成宏观纤维的原理和控制因素。通过优化生长工艺和调整纺丝环境，实现了可加工CNT纤维和薄膜的连续制备。研究了CNT纤维的力学性能与其纳米、微米和宏观尺度下的结构和形貌的关系，侧重于CNT直径、长度、定向性、管壁间的结合力和纤维本身的致密性对负载传递的影响规律。主要通过控制CNT的取向性和堆积密度，使CNT纤维的抗拉强度达到3.76-5.53 GPa，断裂伸长率8-13%，使所制备的CNT薄膜的抗拉强度达到8.0-10.8 GPa，延伸率7-11%，导电率2x10(6次方) S/m。这些强度，延伸率和导电率的综合性能优于目前已报道的所有CNT纤维，传统碳纤维及其它人造纤维。此外，通过原位复合，制备了CNT/聚乙烯醇（PVA）的复合条带和薄膜。通过控制CNT的取向性和体积百分含量，使抗拉强度达到3 GPa以上，高于大部分已报道的CNT或传统碳纤维增强的聚合物基复合材料。本项目的研究成果对开发高性能CNT纤维，促进其在航空航天和汽车领域的实际应用具有十分重要的意义。