【作者】 吴宁；

【导师】 魏取福；

【作者基本信息】 江南大学 ， 纺织工程， 2010， 博士

【摘要】 为制备符合静电纺丝条件的PVAc/TiO2杂化纺丝液,课题根据使用五种抑制剂制备的TiO2溶胶分散液的沉降效果、与PVAc的混溶效果以及粒子的分散情况,最终选择以乙二醇胺为抑制剂的溶胶制备方案并结合静电纺丝工艺制备出PVAc/TiO2杂化纳米纤维。论文使用原子力显微镜(AFM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和傅里叶红外光谱(FTIR)为主要表征手段探索了PVAc/TiO2杂化纳米纤维中PVAc与TiO2溶胶分子的结合方式;研究了纺丝电压、接收装置的距离、周围的环境温度、和纺丝液的性质(粘度、表面张力、电导率等)对杂化纳米纤维的表面形貌和纤维状结构形成的影响;并首先提出了适用于杂化纳米纤维的静电纺丝射流形成的理论模型。课题使用AFM力距离曲线和薄膜拉伸的方法分别测试了单根纳米纤维的强度并分析了纳米纤维膜拉伸性能的影响因素,结果表明:有机无机杂化明显改善了纤维的力学性能;在使用差示扫描量热仪(DSC)、热失重分析仪(TGA)等方法研究杂化纳米纤维的热学性能时,发现有机无机杂化能够明显增强聚合物的热稳定性;论文还对粗糙表面的浸润模型进行了改进,提出了适用于纳米纤维表面的部分浸润模型,并使用静态水滴接触角分析仪对杂化纳米纤维润湿性能进行了测试和分析。结果表明,PVAc/TiO2纳米纤维膜的润湿性能随着TiO2溶胶含量的增加先减小后增大。在基于PVAc/TiO2前驱体制备TiO2纳米纤维的研究中,论文提出将乙酰丙酮作为抑制剂制备PVAc/TiO2溶胶前驱液,再由静电纺丝结合高温煅烧工艺制备出TiO2纳米纤维。使用SEM和X射线衍射仪(XRD)等仪器对样品形貌、晶型以及多孔结构形成的特点进行了表征。结果表明:300-700℃的煅烧过程使得杂化纳米纤维经历了聚合物分解,碳化和形成无机纤维的过程,在此过程中,纤维的表面多孔结构发生了很大变化,纤维的结晶结构也经历了无定形,锐钛矿和锐钛矿/金红石混合晶型三个阶段。为了进一步改善TiO2纳米纤维毡的结构和光催化性能,课题分别制备了不同浓度的Fe3+掺杂、La3+掺杂和Fe3+、La3+共掺杂TiO2纳米纤维并对纤维膜的比表面积、孔隙分布及结晶结构进行了表征。结果表明:适量的掺杂使得TiO2纳米纤维的比表面积和孔隙率明显增大,对TiO2纳米纤维的晶胞参数、晶粒尺寸以及结晶度都有了不同程度的影响。论文还着重讨论了Fe3+掺杂、La3+掺杂和Fe3+、La3+共掺杂在紫外-可见复合光源作用下,对TiO2纳米纤维光催化降解亚甲基蓝性能以及反应动力学的影响机理。结果表明:适量的Fe3+、La3+共掺杂由于协同作用的结果在较大程度上提高了TiO2纳米纤维的光催化活性。更多还原

【Abstract】 In order to preparing the proper PVAc/TiO2 hybrid spinning solution for electrospining process, there were 5 kinds of inhibitors had been evaluated by settlement performance, the mixture compatibility with PVAc solution, and the disperse effect of TiO2 particles for PVAc/TiO 2 hybrid solution preparations. The Diethanolamine was chosen to be the fittest inhibitor for the PVAc/TiO2 sol preparation. The PVAc/TiO2 nanofibers were fabricated by sol-gel process and electrospining technology. The molecular binding mode between PVAc and TiO2 sol were examined by AFM, SEM, TEM and FTIR. The effect of direct voltage, the distance between pinhead and collecting device, the ambient temperature and the properties of spinning solution (viscosity, surface tension, conductivity etc.) on the surface morphologies and fibrous structures of hybrid nanofibers was investigated. The theoretical model of the hybrid nanofiber jets formation had been established in the thesis.The AFM force-distance curves and film elongation tests were employed to analyze the strength of single nanofiber and the elongation behaviors of nanofiber films, the results revealed that the mechanical properties were obvious improved after organic/inorganic hybridization. The DSC and TG analysis presented a better thermal stability after hybridization. The surface wettability mathematical model for nanofiber surface was established based on coarse surface moistening model. The static contact angle analyzer was employed to test the wettability of hybrid nanofiber films, the results showed that the wettability was decreased first then increased as the increasing of TiO2 sol contents.On the research process of preparing the TiO2 nanofibers based on PVAc/TiO2 precursor, the diacetone was used as the inhibitor to prepare the PVAc/TiO2 precursor. After electrospinning and calcinations process, the TiO2 nanofibers obtained. The SEM observations presented a significant difference in the surface morphologies and porous structures as the calcinationtemperature increased, the XRD was employed to analyze the change of crystal forms. The experimental results indicated that the hybrid nanofibers went through polymer decomposition, carbonization and inorganic nanofibers formation process. The results also revealed that the porous structures of these nanofiber films were changed a lot and the crystal forms also changed from amorphous to anatase and rutile mixture crystal form.TiO2 nanofiber films with different contents of Fe3+doped, La3+doped and Fe3+, La3+co-doped were prepared for improving the photocatalysis properties, and the specific surface area, poredistribution and crystal structure were characterized.The results showed that the defined amount of metal ions doped in the TiO2 nanofiber films can obviously increase the specific surface area and porosity, it can also influence the cell parameter, grain size and degree of crystallinity in different extents. The degradation of methylene blue properties and the reaction kinetics mechanism under UV-Vis compose illuminants were investigated. The results from the photocatalysis measurements indicated that the photocatalytic activity of TiO2 nanofibers were improved by doping the defined amount of Fe3+, La3+ all together.更多还原