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利用低温氮气吸附法系统研究了吸附聚丙烯酸 (PAA)的量对纳米碳管表面特征的影响 .分析结果表明 :当PAA吸附量增加到 2 68 98mg·g-1时 ,纳米碳管的比表面积下降了 46 97% ;虽然吸附PAA后的纳米碳管在 1 8nm以上的孔径分布特征基本上与原样一致 ,但孔容减少 ,这部分孔对比表面的贡献明显降低 ,同时出现 1 8nm以下的孔 ;通过氮气吸附等温线利用热力学方法计算的纳米碳管的表面分维值 (surfacefractaldimension)dSF由原样的 2 5 4下降至吸附后的 2 48,表明吸附PAA分子能够降低纳米碳管的粗糙度 .这些说明堵孔效应和屏蔽效应是纳米碳管表面特征改变的主要因素 ,这一研究对纳米碳管在吸附、催化等方面的应用有着非常重要的意义 .
The effect of the amount of polyacrylic acid (PAA) adsorbed on the surface of carbon nanotubes was studied systematically by low temperature nitrogen adsorption method.The results showed that when the PAA adsorption amount increased to 2 6898 mg · g-1, the specific surface area Decreased by 46 97%. Although the pore size distribution of the carbon nanotubes after adsorption of PAA was basically the same as that of the original sample, the pore volume decreased and the contribution of the partial pore to the surface decreased obviously. Meanwhile, the pores below 18 nm ; The surface fractal dimension dSF of the carbon nanotubes calculated by the nitrogen adsorption isotherm was reduced from an original value of 254 to a value of 2 48 after adsorption, indicating that adsorption of PAA molecules can reduce the roughness of the carbon nanotube. These results show that the plugging effect and the shielding effect are the main factors that change the surface characteristics of carbon nanotubes. This research is very important for the application of carbon nanotubes in adsorption and catalysis.