混合稀释剂配比对热致相分离法聚偏氟乙烯中空纤维膜的影响

Effect of Diluent Mixing Ratio on PVDF Hollow Fiber Membrane Fabricated by Thermally Induced Phase Separation

基于聚合物溶剂相容性原理,以γ-丁内酯和十二醇混合溶剂作为热致相分离法制备聚偏氟乙烯(PVDF)中空纤维膜的稀释剂,在聚合物含量固定的前提下,考察了混合稀释剂配比对PVDF中空纤维膜结构和性能的影响。结果表明,当混合稀释剂中γ-丁内酯含量超过30%(质量分数,下同)时,PVDF/稀释剂体系在降温过程中优先发生固液相分离,膜断面呈现球状粒子结构,该结构膜孔间贯通性较差,对应孔隙率和纯水通量最低,抗化学性能差;当γ-丁内酯含量低于30%时,PVDF/稀释剂体系在降温过程中优先发生液液相分离,体系能够通过旋节分相得到的双连续结构,交错互联的膜结构保证了中空纤维膜拉伸强度和抗化学性能更为优异。

This paper reported an investigation on the effect of mixing ratio of γ-butyrolactone and dodecanol on the morphology and properties of poly（vinylidene fluoride） （PVDF） hollow fiber membranes fabricated by a thermally induced phase separation method on the basis of principle of polymer-solvent compatibility. It was found that a solid-liquid phase separation between PVDF and dilutes occurred with a decrease of temperature when the fraction of y-butyrolactone in the mixing diluents exceeded 30 wt %. A spherical structure was formed in the membrane, thus resulting in poor pore connectivity, low porosity, low pure water permeability and poor chemical resistance.When the fraction of y-butyrolactone was less than 30 wt %, a liquid-liquid phase separation took place with a decrease of temperature. In this case, a cross-linking bi-continuous structure was formed, which led to high tensile strength and good chemical resistance for the hollow fiber mem-branes.