碳纳米管的分散性研究及其与聚乙烯醇复合纤维的制备

发布时间：2019-03-18 11:48

【摘要】：本课题分别用物理和化学的方法对多壁碳纳米管(MWCNTs)进行表面修饰,使其接枝亲水基团,进而改善其在溶剂中的分散性。将改性后的碳纳米管与聚乙烯醇(PVA)共混,经过湿法纺丝和热拉伸制得PVA/MWCNTs复合纤维,并对其结构和性能进行了研究,主要研究内容与结论如下:(1)通过傅克烷基化反应将PVA接枝到MWCNTs的表面,通过对比优化出最佳反应条件,核磁共振(13C NMR)和拉曼光谱(Raman spectra)证明了PVA和碳管之间的化学键连接。将制得的功能化MWCNTs(f-MWCNTs)在溶剂(DMSO/H2O(vol ratio=3/1))中进行分散,并在室温下放置一定时间,观察其分散情况,并通过紫外-可见分光光度计(UV-vis),透射电子显微镜(TEM)观测其分散程度,结果表明碳纳米管能够在溶剂中均匀地分散。另外,传统的以王水处理MWCNTs使其表面带上羧基进而改善其水溶性的方法也作为对比试验进行。实验及测试结果表明,王水处理过的MWCNTs表面有严重的破坏,碳管表面的石墨烯层存在大量的缺陷,而傅克烷基化处理的碳纳米管结构几乎没有受到破坏。(2)将最佳分散的f-MWCNTs和PVA通过湿法纺丝工艺制备PVA/f-MWCNTs复合纤维并进行热拉伸。对制成的纤维进行力学,热学,表面形貌和导电性能进行研究,结果表明,PVA/f-MWCNTs复合纤维的强度和模量与纯PVA纤维对比分别增加了280.6%和421.0%。差示扫描量热法(DSC)结果说明碳纳米管的引入降低了PVA的结晶性能,而扫描电子显微镜(SEM)图像间接说明了在复合纤维中,一开始随着碳纳米管含量的增加碳纳米管与聚合物基体之间的结合力逐渐变大,而当碳管含量达到一定的含量时,会发生团聚现象,进而对复合纤维力学和导电性能都产生严重影响。王水处理的碳管在相同条件下所得纤维无论是热稳定性还是力学性能都远远低于f-MWCNTs复合纤维。(3)作为与化学修饰的对比,用迷迭香酸(RosA)和其他几种分散剂(单宁酸,十二烷基苯磺酸钠和原花青素)分别对碳纳米管进行表面修饰,在室温条件下放置一段时间,观察其分散性,并采用TEM,UV-vis光谱对溶液进行表征,结果表明经过RosA修饰的碳纳米管(m-MWCNTs)能够在室温下稳定分散在水溶液中达30天,TEM表明碳纳米管的规整石墨烯结构并没有遭到破坏。核磁共振氢谱(1H NMR)和拉曼光谱结果表明多壁碳纳米管和RosA之间存在???堆垛的相互作用。(4)把经RosA修饰的碳管和聚乙烯醇溶液进行共混,通过湿法纺丝以及热拉伸的工艺制成PVA/m-MWCNTs复合纤维并进行表征。DSC表明了m-MWCNTs的引入相当于在体系中引入了成核剂,其结晶变得更加容易。力学性能的测试表明碳管的引入能够提高纤维的强度和模量,同时不会对纤维表面造成大的影响。
[Abstract]:In this paper, the surface modification of multi-walled carbon nanotubes (MWCNTs) was carried out by means of physical and chemical methods, and the hydrophilic groups were grafted onto them to improve their dispersibility in solvent. The modified carbon nanotubes (CNTs) were blended with polyvinyl alcohol (PVA), and the PVA/MWCNTs composite fibers were prepared by wet spinning and hot drawing. The structure and properties of the composite fibers were studied. The main contents and conclusions are as follows: (1) PVA was grafted onto the surface of MWCNTs by Fourier alkylation, and the optimum reaction conditions were optimized by comparison. Nuclear magnetic resonance (13C NMR) and Raman spectroscopy (Raman spectra) proved the chemical bonding between PVA and carbon tube. The functionalized MWCNTs (f-MWCNTs) was dispersed in the solvent (DMSO/H2O (vol ratio=3/1) and placed at room temperature for a period of time to observe its dispersion. The dispersion was observed by ultraviolet-visible spectrophotometer (UV-vis). The degree of dispersion of CNTs was observed by transmission electron microscope (TEM). The results showed that CNTs could be dispersed uniformly in solvent. In addition, the traditional treatment of MWCNTs with Wang Shui to bring carboxyl groups on its surface and improve its water solubility was also carried out as a contrast test. The experimental and test results show that the surface of MWCNTs treated by Wang Shui has serious damage, and there are a lot of defects in the graphite layer on the surface of carbon tube. However, the structure of CNTs treated by Fourier alkylation was almost undamaged. (2) the best dispersed f-MWCNTs and PVA were prepared by wet spinning and hot drawing of PVA/f-MWCNTs composite fibers. The mechanical, thermal, surface morphology and conductive properties of the fibers were studied. The results showed that the strength and modulus of PVA/f-MWCNTs composite fibers were 280.6% and 421.0% higher than those of pure PVA fibers, respectively. The results of differential scanning calorimetry (DSC) (DSC) showed that the introduction of CNTs decreased the crystallization properties of PVA, while the (SEM) images of scanning electron microscopy (SEM) indirectly showed that in the composite fibers, the crystalline properties of CNTs were decreased. At first, with the increase of the content of carbon nanotubes, the bonding force between carbon nanotubes and polymer matrix gradually increased, but when the content of carbon nanotubes reached a certain content, there would be agglomeration phenomenon. Furthermore, the mechanical and conductive properties of composite fibers are seriously affected. The thermal stability and mechanical properties of the carbon tube treated by Wang Shui under the same conditions are much lower than that of the f-MWCNTs composite fiber. (3) as a comparison with the chemical modification, the fiber obtained by Wang Shui is much lower in thermal stability and mechanical properties. Carbon nanotubes (CNTs) were modified with rosemary acid (RosA) and other dispersants (tannic acid, sodium dodecyl benzene sulfonate and procyanidins) respectively. The dispersion of CNTs was observed at room temperature for a period of time. The dispersion of CNTs was observed by TEM,. The solution was characterized by UV-vis spectra. The results showed that RosA-modified carbon nanotubes (m-MWCNTs) could be stably dispersed in aqueous solution for up to 30 days at room temperature. TEM showed that the regular graphene structure of CNTs was not destroyed. Nuclear magnetic resonance (1H NMR) and Raman spectra show that there exists between multi-walled carbon nanotubes (MWNTs) and RosA. Stacking interaction. (4) blending of RosA modified carbon tubes and polyvinyl alcohol solution. PVA/m-MWCNTs composite fibers were prepared by wet spinning and hot drawing. It was shown that the introduction of m-MWCNTs was equivalent to the introduction of nucleating agent in the system, and its crystallization became easier. The test of mechanical properties shows that the introduction of carbon tube can improve the strength and modulus of the fiber, but it has no great effect on the surface of the fiber.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;TQ342.94

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