用电镜照片定量描述多壁碳纳米管的曲折状态

Quantitative description of the tortuosity of multi-walled carbon nanotubes by electron microscopy images

碳纳米管的形貌受制备方法以及各种后处理过程的影响。为了清楚地描述碳纳米管的形貌特征,本文建立了一种用电镜照片对碳纳米管曲折状态进行定量表征的方法。将一定数量多壁碳纳米管的高分辨透射电镜或扫描电镜照片进行观察和统计分析后,通过引入曲折因子(tortuosity factor TF)和计算标尺(calculating scale CS)两个参数,可以定量表征多壁碳纳米管的曲折程度。本文用该方法对三种不同的多壁碳纳米管进行了表征:纳米聚团流化床反应器制备的多壁碳纳米管、浮游法制备的超长阵列多壁碳纳米管以及静电纺聚环氧乙烷纳米纤维中的多壁碳纳米管。结果显示在所统计的计算标尺范围内,不同多壁碳纳米管的曲折因子有着显著的差异,进而根据多壁碳纳米管曲折因子的差异深入分析了制备方法以及处理过程对其形貌的影响。

The morphologies of carbon nanotubes （CNTs） are influenced by the methods of preparation and post-treated processes. In order to describe the morphological features of CNTs clearly, a method to quantitatively characterize the tortuosity of CNTs has been developed in this work by introducing two parameters： Tortuosity Factor （TF） and Calculating Scale （CS） .These two parameters were used to analyze the images of Multi-Walled Carbon Nanotubes （MWCNTs） taken by the High Resolution Transmission Electron Microscopy （HRTEM） and the Scan Electron Microscopy （SEM）. Using this method, three different kinds of MWCNTs were characterized, which were MWCNTs prepared by the catalytic chemical vapor deposition （CCVD） method in a nano-agglomerate fluidized-bed reactor （NAFBR）, MWCNTs embedded in electrospun Poly Ethylene Oxide （PEO） nanofibers and well-aligned long MWCNTs prepared by floating CVD method, respectively. The results show that the three types of MWCNTs possess different TFs with same CS. The information is very important for instructing the preparation and post-treated processes of MWCNTs as well as for preparing MWCNTs/polymer composites.