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以磷酸三乙酯(TEP)为溶剂,采用复合热致相分离法制备聚偏氟乙烯(PVDF)平板膜。借助WXRD、SEM等技术手段,考察了铸膜液中稀释剂二乙二醇单乙醚醋酸酯DCAC含量及凝固浴水中N-N-二甲基乙酰胺(DMAC)含量,对膜结晶行为、结构特征及渗透性能的影响。结果表明,随稀释剂DCAC含量增加,PVDF膜中α晶相增多,膜外表面由光滑变为多孔,内表面由致密的网状连续结构变为球晶,且球晶体积及间隙不断增大。膜断面由对称的致密连续结构转变为球晶结构,且球晶间隙随DCAC含量增加而增大。凝固浴中DMAC含量增加导致膜表皮层变薄,断面球晶孔隙增加,膜厚度增大。球晶间隙的增大有利于膜渗透通量增加,但拉伸强度有所下降。
Polyvinylidene fluoride (PVDF) plate membrane was prepared by the composite thermal induced phase separation method using triethyl phosphate (TEP) as the solvent. With the help of WXRD and SEM, the DCAC content of diethylene glycol monoethyl ether acetate and the content of NN-dimethylacetamide (DMAC) in the casting bath were investigated. The crystallization behavior, structural characteristics, Effect of permeability. The results showed that with the increase of DCAC content, the α crystal phase increased in the PVDF membrane, the outer surface of the membrane changed from smooth to porous, the inner surface changed from dense network structure to spherulite, and the spherulite volume and gap increased . The cross-section of the film transforms from a symmetrical dense continuous structure to a spherulitic structure, and the spherulite gap increases with increasing DCAC content. The increase of DMAC content in the coagulation bath led to the thinning of the epidermis, the increase of the spherulite porosity and the increase of the membrane thickness. The increase of the spherulite gap favors the increase of membrane permeation flux but the decrease of tensile strength.