聚全氟乙丙烯中空纤维膜研究

以聚全氟乙丙烯(FEP)为成膜聚合物,复合无机粒子为成孔剂,邻苯二甲酸二辛酯(DOP)为稀释剂,采用熔融纺丝工艺制备得到FEP中空纤维膜.分析和讨论了不同成膜体系对FEP中空纤维膜热性能、动态力学性能和力学性能的影响,并对膜的纯水通量和孔径分布进行表征.用扫描电子显微镜(SEM)观察了膜的横断面和表面形貌.结果表明,所得FEP中空纤维膜为由溶出微孔和界面微孔组成的海绵状孔结构.随着成孔剂含量的增加,成孔剂在成膜体系中分散程度变差,容易发生团聚,最终导致膜孔径变大,孔径分布变宽.成孔剂和稀释剂对FEP中空纤维膜的热性能和动态力学性能影响较小.当FEP含量增加到70 wt％时,膜表面容易形成一层致密层,降低了膜的通透性.

STUDIES ON POLY(TETRAFLUOROETHYLENE-co-HEXAFLUOROPROPYLENE) HOLLOW FIBER MEMBRANES

Poly(tetrafluoroethylene-co-hexafluoropropylene)(FEP) hollow fiber membranes were prepared by melt spinning method with FEP as polymer matrix,composite of inorganic particles as pore-forming agent and dioctyl phthalate(DOP) as the diluent.The pure water flux and pore size distribution of the hollow fiber membranes were tested.Effect of FEP and composite of inorganic particles contents on the thermal properties,changes in thermodynamic properties and mechanical properties of the hollow fiber membranes were analyzed and discussed.The cross-section and surface morphologies of the hollow fiber membranes were observed by scanning electronic microscopy(SEM).The results showed that the spongy-like structure could be observed obviously in the cross-section of the hollow fiber membrane,which consisted of dissolved micro-voids and interfacial micro-voids formed by stretching.As the pore-forming agent contents increasing,the dispersed homogeneous degree became worse,which would brought about not only larger pores but also wider pore size distribution.The impact of pore-forming and diluent on the thermal properties and thermodynamic properties of the hollow fiber membranes was little.As the FEP contents reached 70 wt%,the compact layers formed on the hollow fiber surface induced the decrease of FEP hollow fiber membrane permeability.