The multi-walled carbon nanotubes (MWNTs) were modified by mixed strong acids and sulfuryl dichloride (SOCl2) successively. Their solubility in organic solvents and dispersivity in matrix of polyimides were improved greatly by modification. The unmodified and modified MWNTs were characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The polyimide (PI)/MWNTs composites were synthesized by in situ polymerization of 4,4'-diaminodiphenylether (ODA) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), in which the modified MWNTs were used as the fillers. The composites were characterized by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and measurement of capacitance. The results show that the PI/MWNTs composites have preferable heat stability as the same as the pure polyimide (PI). The dynamic mechanical properties improve with the mass fraction of MWNTs increasing. The value of storage modulus is 2.03 GPa at 50 ℃ when the mass fiaction of MWNTs is 10％. Compared with that of the pure PI, the storage modulus increases by 23.1％. The dielectric properties enhance sharply with the mass fraction of MWNTs increasing. For the nanocomposites containing 10％ of MWNTs, the dielectric constant reaches 66.7 at 1 MHz, which comes up to 18.6 times of that of pure polyimide.Therefore, The MWNTs/PI is a kind of nanocomposite material with favorable properties of thermal properties, dynamic mechanical properties and dielectric properties.%依次用混强酸和SOCl2对多壁碳纳米管(MWNTs)进行改性,解决其在有机溶剂的溶解性和在基体聚酰亚胺中分散性问题,并采用光电子能谱(XPS)和透射电镜(TEM)对改性前后的MWNTs进行表征.以4,4'-二氨基二苯醚(ODA)和3,3',4,4'-二苯甲酮四羧酸二酐(BTDA)为原料,以原位聚合法将改性碳纳米管掺杂聚酰亚胺(PI),制备MWNTs/PI纳米复合材料.通过热重分析(TGA)、动态力学分析(DMA)和电容测试对材料的热性能、动态力学和介电性能进行表征.结果表明:加入MWNTs后,材料仍有很好的热稳定性,材料的动态力学性能随MWNTs增加而增强,在50℃和10%(质量分数)MWNTs时储能模量为2.307 GPa,比纯聚酰亚胺(PI)提高23.1%;材料的介电常数随着MWNTs含量的增加明显提高,在IMHz和10%时介电常数为66.7,是纯PI的18.6倍.制备的碳纳米管/聚酰亚胺材料是一种具有优良的热学、动态力学力学和介电性能性能的纳米复合材料.
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