绿色热致相熔融纺丝工艺制备PVDF中空纤维膜成膜机理研究

Polyvinylidene fluoride (PVDF) hollow fiber membranes production process requires a large amount of organic solvent, environmental pollution and the waste of raw materials is very serious. PVDF hollow fiber membranes will be prepared by thermally induced phase melt spinning technology which takes PVDF as membrane material and uses ionic liquids to replace organic solvent as diluents in this study. The membrane formation mechanism of thermal induced phase melt spinning process for preparation of PVDF hollow fiber membrane will be researched, and the membrane microporous structure design, construction, reorganization and optimization mechanism will be explored in the membrane making process. Ionic liquids are expensive，so it will be recycled and reused with hollow fiber nanofiltration membrane. The influence of hollow fiber nanofiltration membrane microstructure, ionic liquid concentration and composition in the spinning waste water, liquid flow status and other factors on the mass transfer performance will be studied. The mass transfer model for the description of ionic liquids through the hollow fiber nanofiltration membrane will be established on the basis of experimental research, and the mass transfer mechanism of recycling ionic liquid in the spinning waste water by hollow fiber nanofiltration membrane will be explored. The membrane formation mechanism of green thermally induced phase melt spinning membrane technology with ionic liquids as diluents for preparation of PVDF hollow fiber membrane will be studied in order to provide theoretical basis and technical supporte for preparation of high performance polymer membrane.

聚偏氟乙烯（PVDF）中空纤维膜工业化生产中需要大量有机溶剂，环境污染和原材料浪费十分严重。本项目以PVDF为膜材料，使用离子液体替代有机溶剂作为稀释剂，采用热致相熔融纺丝工艺研制新型高性能PVDF中空纤维膜，并对热致相熔融纺丝工艺制备PVDF中空纤维膜成膜机理进行研究，探索制膜过程中膜微孔结构的设计、构建、重组及优化机制。离子液体价格昂贵，采用中空纤维纳滤膜对离子液体进行回收再利用，研究中空纤维纳滤膜微观结构、纺丝废水中离子液体浓度和组成、流体的流动状况等因素对传质性能的影响，在实验研究的基础上，建立描述离子液体通过中空纤维纳滤膜的传质模型，并探索中空纤维纳滤膜回收纺丝废水中离子液体传质机理。对以离子液体作为稀释剂的绿色热致相熔融纺丝工艺制备PVDF中空纤维膜成膜机理进行研究，可以为高性能高分子分离膜制备提供理论基础和技术支持。

本项目使用离子液体替代有机溶剂作为稀释剂，采用热致相分离法制备PVDF膜，并对热致相分离法制备PVDF膜成膜机理进行研究，探索制膜过程中膜微孔结构的设计、构建、重组及优化机制。离子液体价格昂贵，本项目采用中空纤维纳滤膜有效回收离子液体，提高其使用效率。.通过热重和电镜测试分析，从7种离子液体中选取1-丁基-1甲基吡咯烷四氟硼酸盐[BMPr][BF4]作为本次研究的主要离子液体。然后，以[BMPr][BF4]为绿色环保稀释剂通过热致相分离(TIPS)熔融工艺制备PVDF中空纤维膜。绘制了PVDF/[BMPr]BF4混合物的相图，并研究了影响PVDF膜形态及性能的因素。对聚偏氟乙烯(PVDF)聚合物在稀释剂[BMPr][BF4]中的结晶演化过程进行了研究，结果发现，膜孔隙率、纯水通量和断裂伸长率随着聚合物浓度的增加而减小，而膜的断裂强度则相应增加，空气浴中纯水通量在PVDF质量分数为30%最高达1892.8L/m2h。同样的，凝固浴对膜性能影响也很大。通过差示扫描量热(DSC)和红外光谱分析(FTIR)等研究了在不同PVDF浓度下的结晶行为，实验发现，在该体系中，离子液体对其没有影响。中空纤维纳滤膜可以对纺丝废水中的离子液体进行有效截留，回收的离子液体性质稳定，回收效果良好。.对以离子液体为稀释剂的绿色热致相熔融工艺制备PVDF膜成膜机理进行研究，为高性能高聚物分离膜的制备提供理论基础和技术支持。