稀释剂种类对聚偏二氟乙烯多孔膜性能的影响

Effects of Diluent Types on Properties of Poly(vinylidene fluoride)Porous Membrane

以聚偏二氟乙烯(PVDF)为原料,邻苯二甲酸二丁酯(DBP)和二苯甲酮(DPK)为稀释剂,通过不同的相分离机理(固-液相分离或液-液相分离)制备了不同结构和性能的多孔膜。建立了聚合物/稀释剂体系的二元相图,同时采用扫描电子显微镜(SEM)、孔隙率和水通量测试、差示扫描量热仪(DSC)和X射线衍射仪(XRD)对多孔膜的结构和性能进行表征。研究结果表明:由PVDF/稀释剂体系制备的多孔膜断面结构主要为表面带有微孔的球粒。PVDF/DPK体系在PVDF含量为20wt%、0℃水浴冷却的条件下获得了双连续结构的多孔膜,其孔隙率和水通量优于同体系其它多孔膜。PVDF多孔膜的结晶度随稀释剂含量的增大而增大,随冷却介质温度的升高而增大。PVDF多孔膜的晶型为α晶型,该晶型不随聚合物含量和冷却介质温度发生变化。

Porous membranes with various structures and properties have been prepared with PVDF as the raw material and DBP or DPK as the diluents through different phase separation mechanisms(Solid-liquid separation or liquid-liquid separation).Phase diagrams of PVDF and the diluents have been established,SEM,Porosity and Water Flux Measurement,DSC and XRD have been used to characterize structures and properties of the porous membranes.The results of the experiments show that the cross-section of the porous membranes prepared by PVDF/diluent system is mainly composed of spherical particles with microporous surface.And bicontinuous structure of membrane can be obtained when the content of PVDF in PVDF/DPK system is 20 wt%and the cooling temperature is 0 ℃.Moreover,both the porosity and water flux of this membrane are better than those membranes prepared under different conditions in PVDF/DPK system.The crystallinity of the membrane increases with the increase of the diluents content and the cooling temperature.The crystal type(α)is not affected by the change of cooling temperature and the content of PVDF.