Processing Of Multi-Walled Carbon Nanotubes And The Interaction With Boron Oxide

Carbon nanotubes have perfect 1D nano-space. Opened carbon nanotubes can be used for nano-cuvette, super sorbent, activator carrier, material storing energy, filling with other substance in it and so on. The present work specialized in the purification and opening of the Multi-walled carbon nanotubes (MWNTs) refluxed in concentrated nitric acid or air oxidation method respectively. Then it was explored to fill the opened MWNTs with B2O3.We study the process of purifying and opening by refluxing the MWNTs in concentrated nitric acid at different temperatures for different times. We found that both at room temperature and 120℃, the reflux process can eliminate the grains of the catalyst. By examining the weight loss of the raw materials, the ratio of the open ends, changes of length and diameter, damage of the MWNTs wall and the amounts of the impurity, we can describe the process with three phases, which the MWNTs was refluxed in concentrated nitric acid at 120℃for 48h. The first phase (0~5h) can be described as purifying phase, with the characters of less weight loss and full wall. The second phase can be described as opening phase (10~20h), in which phase the weight of the raw materials lossed faster, and the length of the MWNTs become short obviously, for the flaw in wall oxided by HNO3. At the end, the ratios of open ends rised quickly above 60% and kept at this measurement. The third phase (20~48h) can be described as destroying phase, in which the wall destroyed seriously resulting to the blurred wall in the end and there only no more than 50wt% MWNTs left. So the MWNTs refluxed in first phase can be used for reinforcement in composites, compared to the second phase for being filled with other materials and the third destroyed.Besides, we used air and CO2 respectively to oxide the MWNTs. As a result, we can find that there are two kinds of carbon substances in the raw MWNTs. One can more resist from oxidation and the other less. The former is made of grains of graphite and full structure MWNTs, with the latter of less full structure MWNTs and amorphous carbon. Moreover, according to the air oxidation, we can find how the reflux processing affecting the MWNTs structure. On the one hand, reflux processing eliminates the impurity apt to oxidation, improving the...