DSC and calorimetric studies of multi-walled carbon nanotubes (MWCNTs) with average diameters in the range 7, 9 and 18 nm were carried out. MWCNTs were obtained by the CVD method. The kinetic processes in MWCNTs were studied from room temperature to 550 °C in a nitrogen flow using differential scanning calorimetry (DSC) on a Perkin – Elmer — 8000. It was found that exo- and endothermic peaks are not observed on the DSC curves after water evaporation. This indicates that all studied MWCNTs have a small number of defects, functional groups, and other impurities. The heat capacity of MWCNTs was measured by the relaxation method in the temperature range from 2 to 275 K by using PPMS. In the temperature dependences of the specific heat were observed that for MWCNTs with the decrease of the temperature below 20 K the curves shift to lower values with an increase the average diameter. The main result was that at temperatures below 45 K with the decreasing of the nanotubes diameter the ratio of heat capacity of nanotubes to the heat capacity of graphite increases. The perfection of structure and low amount of the defects, functional groups and impurity contamination for MWCNTs were demonstrated in the comparison of the XPS and NEXAFS spectra for these nanotubes with CVD prepared nanotubes (18 nm) after mechanical and chemical functionalization.

对平均直径在7、9和18 nm范围内的多壁碳纳米管（MWCNT）进行了DSC和量热研究。MWCNT通过CVD方法获得。在Perkin – Elmer — 8000上使用差示扫描量热法（DSC）在氮气流中研究了从室温到550°C的MWCNTs的动力学过程。发现在DSC曲线上未观察到放热峰和吸热峰。水蒸发。这表明所有研究的MWCNT都具有少量的缺陷，官能团和其他杂质。通过使用PPMS，通过松弛法在2至275K的温度范围内测量MWCNT的热容。在比热的温度依赖性中，对于温度低于20 K的MWCNTs，随着平均直径的增加，曲线向更低的值移动。主要结果是，在低于45 K的温度下，随着纳米管直径的减小，纳米管的热容量与石墨的热容量之比增加。通过机械和化学功能化后，将这些纳米管与CVD制备的纳米管（18 nm）的XPS和NEXAFS光谱进行比较，证明了MWCNTs的结构完美，缺陷，官能团和杂质污染的程度低。主要结果是，在低于45 K的温度下，随着纳米管直径的减小，纳米管的热容量与石墨的热容量之比增加。通过机械和化学功能化后，将这些纳米管与CVD制备的纳米管（18 nm）的XPS和NEXAFS光谱进行比较，证明了MWCNTs的结构完美，缺陷，官能团和杂质污染的程度低。主要结果是，在低于45 K的温度下，随着纳米管直径的减小，纳米管的热容量与石墨的热容量之比增加。通过机械和化学功能化后，将这些纳米管与CVD制备的纳米管（18 nm）的XPS和NEXAFS光谱进行比较，证明了MWCNTs的结构完美，缺陷，官能团和杂质污染的程度低。