【作者】 王庐岩；

【导师】 钱英；

【作者基本信息】 北京工业大学 ， 环境工程， 2002， 硕士

【摘要】 聚偏氟乙烯(PVDF)作为膜材料由于其疏水性而在应用中受到限制。本论文中，通过加入亲水性聚合物聚甲基丙烯酸甲酯(PMMA)与聚砜酰胺(PSA)与PVDF分别进行共混以提高PVDF膜材料的亲水性，并对PVDF／PMMA与PVDF／PSA共混体系的相容性及成膜机理进行研究。 利用溶解度参数法、绝对粘度法、玻璃化转变温度法等方法确定了共混体系的相容性：PVDF／PMMA共混体系为完全相容体系，PVDF／PSA共混体系为部分相容体系。根据共混体系的相容性等因素对膜性能的影响，采用正交设计方法，利用浸入沉淀相转化法制备共混分离膜，得到具有最佳成膜性能的铸膜液组成及凝胶条件。其中对PVDF／PSA共混膜的研究具有创新性。 在总结单组分聚合物相转化法成膜机理的基础上，利用浊点相图、测定凝胶速度等方法对PVDF共混体系在PEG、LiCl作添加剂，以及水、乙醇水溶液、氯化钠水溶液、DMAC水溶液为凝胶剂条件下成膜的相分离和凝胶传质过程进行了研究。在PVDF／PMMA体系中，PEG含量增加使体系相分离过程延长，膜孔径变小。而在PVDF／PSA体系中，PEG为成孔剂，LiCl为增容剂，两者相互作用使膜结构致密且孔隙率较高。两共混体系在不同凝胶剂中按照溶剂-非溶剂相互作用由大到小，分相时间逐渐延长，膜由大孔向致密结构变化。PVDF／PMMA体系的凝胶传质过程服从Fick扩散定律，并且由于其完全相容性，成膜时PVDF与PMMA同时沉淀，膜中不含PVDF结晶。PVDF／PSA体系凝胶过程不服从Fick扩散，体系的部分相容导致成膜时两组分独立沉淀，膜中存在少量PVDF结晶。更多还原

【Abstract】 Due to the hydrophobicity of poly(vinylidene fluoride)(PVDF), the application of PVDF membrane was limited. In this paper, poly(methyl methacrylate)(PMMA) and polysulfonamide(PSA) were respectively introduced as the second polymer component to hydrophilized PVDF membrane. The miscibility of PVDF blends and the formation mechanism of PVDF blend membranes were investigated.The miscibility of PVDF blends in N,N-dimethyl acetamide(DMAC) were characterized by solubility parameter, glass transition temperature and viscosity, etc. The result showed PVDF/PMMA blend system is completely miscible while PVDF/PSA blend system is partially miscible. Based on the miscibility, hydrophilicity, polymer concentration etc.,the optimal composition and conditions for preparing PVDF membranes was obtained by normalization design method.According to the formation mechanism of single-polymer casting solution by immersion precipitation phase inversion process, we studied the formation mechanism of PVDF blend membranes under different conditions. Poly(ethylene glycol) (PEG) and (lithium chloride) (LiCl) were selected as additives ,and water, ethanol aqueous solution, sodium chloride aqueous solution and DMAC aqueous solution as coagulating bath, when the content of PEG in PVDF/PMMA casting solution rised, the phase separationiiwas delayed, which resulted in compacted membranes structure. For PVDF/PSA casting solution, PEG was the pore-former and LiCl was the cosolvent. With the decreasing of solvent-nonsolvent interaction, the phase separation time of PVDF blend casting solutions in different coagulation became longer and macrovoids in membrane structures smaller. The diffusion of solvent-nonsolvent in the gelation process of PVDF/PMMA accorded with Pick diffusion law, and PVDF and PMMA precipitated simultaneously because of the good miscibiiity between them. So PVDF crystal grain was not found in membranes. While the diffusion in the formation process of PVDF/PSA membrane did not obey Pick diffusion law, and the partial miscibiiity made PVDF and PSA precipitated respectively. Therefore, a few PVDF crystal grains could be observed in PVDF/PSA blend membranes.更多还原