低温静电纺丝技术制备多孔结构微纳米陶瓷纤维及其成孔机理研究

The porosity and specific surface area are key factors for the performances of micro-nano ceramic fibers when applied in the fields of high temperature filtration, sound absorption and efficient catalysis, which makes it necessary to increase porosity and specific surface area of ceramic fiber to improve its performance. Fabrication of porous ceramic fibers having higher porosity and specific surface area than ordinary ceramic fibers is an important issue in the field of ceramic materials. In this project, freeze drying technology is introduced to the process of electrospinning. Two spinning solutions (the spinning sol and spinning suspension) are electrospun in the low-temperature environment, during which the liquid fibers (stretch the spinning solution into the silks) do not volatilize or only a little. Then, the solvent of liquid fibers is frozen in low-temperature environment. Porous ceramic fibers are obtained by freeze drying using solvent crystals as templates. To control the size, morphology, distribution and quantity of pores in porous ceramic fibers, key technologies of the porous ceramic fibers made by freeze-electrospinning and the crystallization law of decentralized system with one-dimensional structure in the electrostatic field are studied. This project will lay a foundation for paperation of high performance ceramic fiber materials.

微、纳米陶瓷纤维在高温过滤、吸声隔音和高效催化等领域应用时，其孔隙率和比表面积是影响性能的关键因素。如果在陶瓷纤维中制备一定数量的孔洞，则可以获得相对更高的孔隙率和比表面积，从而表现出优异的性能，所以制备具有多孔结构的陶瓷纤维成为目前陶瓷材料领域中的研究热点之一。本项目在静电纺丝过程中引入冷冻干燥技术，将纺丝液（纺丝溶胶和纺丝悬浊液）在低温环境中静电纺丝，控制电纺形成的液态纤维（拉伸成丝的纺丝液）不挥发或极少量挥发，并使其中的溶剂在低温下结晶，溶剂的结晶体在冷冻干燥后留下孔洞，最终获得多孔陶瓷纤维。重点研究低温静电纺丝制备多孔陶瓷纤维的工艺，揭示微米或纳米尺度下一维结构的分散体系在静电场下的低温结晶规律，并总结其成孔机理，实现对多孔陶瓷纤维中孔的尺寸、形态、分布和数量等的控制，为制备高性能陶瓷纤维材料奠定基础。

微纳米陶瓷纤维在高效过滤和高效催化等方面应用时，其孔隙率和比表面积是影响性能的关键因素，如何增大陶瓷纤维的孔隙率和比表面积以提高其性能是一个亟待解决的问题。由于多孔陶瓷纤维具有孔洞结构，相对于普通纤维可以获得更高的孔隙率和比表面积，所以研究多孔陶瓷纤维的制备技术是目前陶瓷纤维领域中的重要课题。本项目在静电纺丝过程中的引入冷冻干燥技术，将纺丝液在低温环境中静电纺丝，控制电纺形成的液态纤维极少量挥发，使其中的溶剂在低温下结晶，以溶剂的结晶体为模板在冷冻干燥后留下孔洞，来获得多孔陶瓷纤维，并对孔形成的机理进行了深入的研究。首先，研究了适于低温静电纺丝的三种体系纺丝液的物理性质和可纺性，以及纺丝液在温度场和静电场作用下的结晶行为；其次，研究了静电纺丝工艺和冷冻干燥工艺对多孔陶瓷纤维中孔的形态、分布以及纤维性能的影响；最后，揭示了微米或纳米尺度下一维结构的分散体系在静电场下的低温结晶规律，从而得出陶瓷纤维上孔洞的形成机理；此外，还探索了多孔陶瓷纤维的辅助成孔工艺以及提高陶瓷纳米纤维比表面积的新方法。项目研究取得了系列有重要创新意义的基础研究成果，部分工作达到国际前沿水平，已经在国际学术刊物（SCI）上发表学术论文8篇，申请了中国发明专利5项。