Functionalization and strengthening of graphitized untwisted carbon nanotube yarn with hot mixed acid treatment
Functionalization and strengthening of graphitized untwisted carbon nanotube yarn with hot mixed acid treatment
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DOI：
10.1299/transjsme.19-00029
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
K. Okumo;Y. Takahashi;Tae Sung Kim;Hidefumi Nikawa;A. Hosoi;H. Kawada
中科院分区：
文献类型：
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作者：
K. Okumo;Y. Takahashi;Tae Sung Kim;Hidefumi Nikawa;A. Hosoi;H. Kawada
碳纳米管（CNT）具有优异的力学性能和低密度。由于碳纳米管的长度有限，碳纳米管纱线被视为碳纤维增强塑料的增强纤维。然而，CNT纱线不具有如单个CNT那样显著的机械性能。提高碳纳米管纱线机械性能的最常用方法是与聚乙烯醇或聚酰亚胺等聚合物制成复合材料。如果在碳纳米管表面引入羧基等官能团，可以改善碳纳米管与聚合物之间的相互作用，从而获得高的力学性能。在这项研究中，未加捻的碳纳米管纱线制备通过拉伸垂直排列的碳纳米管通过模具和功能化与混合酸。混酸在碳纳米管表面引入官能团的同时也引入了缺陷。为了减少缺陷，CNT纱线在混合酸处理之前在2800°C的温度下石墨化。通过石墨化处理，提高了CNT纱线的结晶度并去除了无定形碳。XPS分析的结果是，用混合酸处理的石墨化CNT纱线不含官能团。另一方面，用热混合酸（90°C）处理的石墨化CNT纱线含有官能团。该纱线的结晶度比原样CNT纱线高4.5倍。此外，作为单纤维拉伸试验的结果，与原样CNT纱线相比，该纱线的拉伸强度增加了79%，杨氏模量增加了173%。
Carbon nanotubes (CNT) have remarkable mechanical properties and low density. Since length of the CNT is limited, CNT yarn is regarded as a reinforced fiber of carbon fiber reinforced plastics. However, the CNT yarn does not have remarkable mechanical properties such as the individual CNT. The most popular way for improving the mechanical properties of the CNT yarn is to make composites with polymer such as polyvinyl alcohol or polyimide. If some functional groups such as carboxyl groups are introduced on the surface of CNTs, interaction between the CNTs and the polymer is improved and high mechanical properties will be obtained. In this study, untwisted CNT yarns were prepared by drawing vertical aligned CNTs through a die and functionalized with mixed acid. Mixed acid introduced not only the functional groups but also defects on the surface of CNTs. For reducing the defects, the CNT yarn was graphitized at a temperature of 2800°C before the mixed acid treatment. By the graphitization treatment, crystallinity of the CNT yarn was improved and amorphous carbon was removed. As a result of XPS analysis, a graphitized CNT yarn treated with mixed acid did not contain the functional groups. On the other hand, a graphitized CNT yarn treated with hot mixed acid (90°C) contained the functional groups. Crystallinity of this yarn was 4.5 times higher than the as-received CNT yarn. In addition, as a result of single fiber tensile tests, tensile strength of this yarn was increased by 79 % and Young’s modulus was increased by 173 % compared to the as-received CNT yarn.