MWNTs表面处理及其对PI薄膜力、电、热性能的影响

发布时间：2018-03-31 02:31

  本文选题：聚酰亚胺　切入点：碳纳米管　出处：《哈尔滨理工大学》2015年硕士论文

【摘要】：聚酰亚胺(PI)薄膜基于其本身的高绝缘性能、耐高低温性能、高强度等优点，在F、H级电机、变压器、电器绝缘、柔性印刷线路板、手机、电脑等电器电子行业具有广泛应用[1-2]。然而，随着对电子器件微型化发展的需要，PI薄膜的性能也有待提高。近年，无机纳米粒子改性PI薄膜的研究工作在不断开展，采用碳纳米管(MWNTs)改性PI薄膜已经取得了一定研究成果[3-5]，但主要集中于对其耐电晕、耐击穿性能的改善，而对两相复合体系力、电、热综合性能的测试及分析比较少见。MWNTs作为一维长纤维状材料，，除具有极佳的导电性能外，也拥有较高的强度和耐热性能，将其添加到PI基体中，势必会对薄膜的力、电、热综合性能产生影响，然而MWNTs表面能大，易团聚，不易在基体中分散，进而限制了其长纤维作用的发挥。因此，本文采用不同方式对MWNTs进行表面处理，并将表面处理后的MWNTs添加到PI基体中，研究表面处理后的MWNTs对薄膜力、电、热性能的影响。 本文采用原位聚合法，以均苯四甲酸二酐(PMDA)和4,4′-二胺基二苯醚(ODA)为原料，将表面处理后的MWNTs与单体混合制备MWNTs/PAA杂化胶液，模拟工业流延法进行铺膜，最后经热亚胺化制得PI薄膜。MWNTs的表面处理效果影响因素众多，本文采用超声法、混酸法和芬顿法三种方法对MWNTs进行表面处理，探讨影响MWNTs表面处理效果的因素，以期通过表面处理后的MWNTs来提高PI薄膜的拉伸强度，并在此条件下，研究表面处理后的MWNTs对PI薄膜介电性能和热性能的影响。SEM测试结果表明，经超声法处理后的MWNTs缠结被解开，经混酸处理4h、8h、12h后的MWNTs被切短，缠结现象明显减少，MWNTs长度分布也变小，能较均匀的分散在乙醇溶液中；FTIR测试结果表明，经混酸法处理后的MWNTs表面接枝上了羧基以及羟基官能团，经芬顿法处理后的MWNTs表面接枝上了羟基官能团；XRD测试结果表明，经混酸法处理后的MWNTs使PI薄膜的分子有序度提高。MWNTs/PI复合薄膜拉伸测试结果显示，混酸处理8h的MWNTs改性的PI薄膜拉伸强度值大于混酸处理4h和12h的MWNTs改性的PI薄膜，芬顿试剂处理的MWNTs使PI薄膜的拉伸强度值大于混酸处理的MWNTs改性的PI薄膜，且其介电常数和介电损耗相对较低，使薄膜的介电强度提升更为明显；在MWNTs添加量为2.0wt%时，混酸处理的MWNTs改性的PI薄膜和芬顿试剂处理的MWNTs改性的PI薄膜仍表现出良好的绝缘性。芬顿法处理的MWNTs更好地兼顾了复合薄膜的拉伸性能和介电性能。热性能测试结果表明，在本实验添加量下，经表面处理后的MWNTs的加入并未对PI薄膜的热分解温度产生明显影响。
[Abstract]:Polyimide (Pi) thin film based on its own high insulation, high and low temperature resistance, high strength and other advantages, in FG class motor, transformer, electrical insulation, flexible printed circuit board, mobile phone, The electrical and electronic industries such as computer have been widely used [1-2]. However, the properties of Pi thin films need to be improved with the development of miniaturization of electronic devices. In recent years, the research work of inorganic nanoparticles modified Pi thin films has been carried out continuously. Some research results have been obtained by using MWNTs to modify Pi thin films, but the main focus is on improving the corona resistance and breakdown resistance of Pi films, while on the two phase composite system. The test and analysis of thermal comprehensive properties are rare. MWNTs, as one dimensional long fibrous material, not only have excellent electrical conductivity, but also have high strength and heat resistance. Adding them to Pi matrix is bound to affect the force and electricity of the film. However, the surface energy of MWNTs is large, it is easy to agglomerate, and it is not easy to disperse in the matrix, which limits the function of long fiber. Therefore, the surface treatment of MWNTs is carried out in different ways in this paper. The surface treated MWNTs was added to Pi substrate to study the effect of surface treated MWNTs on the mechanical, electrical and thermal properties of the film. In this paper, in situ polymerization, MWNTs/PAA hybrid solution was prepared by mixing the surface treated MWNTs with monomers from PMDAs of tetracarboxylic acid (PMDAA) and 4H4C4-diamino-diphenyl ether (ODAA), and the film was prepared by simulated industrial flow casting method. Finally, there are many factors affecting the surface treatment effect of Pi film. In this paper, ultrasonic method, mixed acid method and Fenton method are used to treat the surface of MWNTs, and the factors that affect the surface treatment effect of MWNTs are discussed. In order to improve the tensile strength of Pi films by surface treated MWNTs, the effects of MWNTs on the dielectric and thermal properties of Pi films were studied under these conditions. The results showed that the MWNTs entanglement after ultrasonic treatment was solved. After being treated with mixed acid for 4 h or 8 h or 12 h, the MWNTs was cut short, the entanglement phenomenon was obviously reduced and the length distribution of MWNTs was also reduced. The results of FTIR measurements showed that the surface of MWNTs treated by mixed acid treatment was grafted with carboxyl groups and hydroxyl functional groups. After Fenton method, hydroxyl functional groups were grafted on the surface of MWNTs. The results showed that the MWNTs treated by mixed acid method increased the molecular order of Pi films. The tensile strength of Pi film modified by MWNTs for 8 h was higher than that of Pi film modified by MWNTs for 4 h and 12 h after mixed acid treatment. The tensile strength of Pi film treated by Fenton reagent was higher than that of Pi film modified by MWNTs treated with Fenton reagent. The dielectric constant and dielectric loss of the films are relatively low, which makes the dielectric strength of the films more obvious, and when the content of MWNTs is 2.0 wt%, The Pi film modified by MWNTs and MWNTs modified by Fenton reagent still show good insulation. The tensile and dielectric properties of the composite film are better taken into account by Fenton MWNTs. The addition of MWNTs after surface treatment has no obvious effect on the thermal decomposition temperature of Pi films.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.2;TQ317

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