PVDF微孔膜的制备和性能研究

Preparation and properties of PVDF microporous membranes

针对聚偏氟乙烯(PVDF)膜的生产工艺中有机溶剂消耗量大、环境污染和原料浪费严重的问题,提出以绿色热致相分离法制备PVDF微孔膜的方法。该方法以聚偏氟乙烯为制膜材料,以绿色溶剂-离子液体1-丁基-3-甲基咪唑四氟硼酸盐([BMIm]BF4)为稀释剂,替代传统工艺中的有机溶剂。通过研究PVDF/[BMIm]BF4二元体系中膜的形态、晶体结构、膜的性能等探讨了改变PVDF和[BMIm]BF4二元体系中PVDF的质量分数对PVDF微孔膜的成膜过程、膜结构和膜性能的影响。研究结果表明:随PVDF质量分数增大,微孔膜纯水通量和孔隙率降低,结晶温度呈上升趋势;冷却高温的PVDF/[BMIm]BF4混合溶液将发生固-液相分离;PVDF初始质量分数的变化不会影响PVDF微孔膜的晶型结构。该研究优化了绿色热致相熔融纺丝工艺技术路线,为高分子分离膜制备提供了理论指导和技术支持。

In the production process of polyvinylidene fluoride（PVDF）films,the organic solvent consumption,environmental pollution,and waste of raw materials were serious.To solving these problems,a method for preparing PVDF microporous membrane by green thermally induced phase separation method was proposed.The polyvinylidene fluoride were selected as the film forming material,and a green solvent-ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate（[BMIm]BF4）was used as a diluent to replace the organic solvent in the conventional process.The effects of PVDF mass fraction on the film formation,structure and properties of PVDF microporous membranes were investigated by membrane morphology,crystal structure and membrane performance of PVDF/[BMIm]BF4binary system,.It was found that the flux and porosity of microporous membrane decreased while the crystallization temperature increased with the increase of PVDF concentration.The PVDF/[BMIm]BF4 mixed solution will undergo solid-liquid phase separation during the cooling process.The crystalline structure of PVDF microporous membrane was not affected by the initial concentration of PVDF.The green thermotropic phase melt spinning technology route were optimized in this work,which provided theoretical guidance and technical support for the preparation of polymer membrane.