热致相分离法制备聚偏氟乙烯中空纤维膜

发布时间：2018-05-25 01:16

本文选题：聚偏氟乙烯 + 中空纤维膜　；参考：《北京工业大学》2015年硕士论文

【摘要】：聚偏氟乙烯(PVDF)是一种半结晶型聚合物,晶区赋予其很好的热稳定性,无定形区使其较柔韧。同时,聚偏氟乙烯具有很好的化学稳定性,在室温下不被酸、氧化剂和卤素所腐蚀,对脂肪烃、芳香烃、醇和醛等有机溶剂也很稳定,并且耐γ射线和紫外线辐射。近年来,聚偏氟乙烯作为一种性能优异的膜材质,越来越得到人们的认可。制备聚偏氟乙烯微孔膜的常用方法包括熔融拉伸(MS-S)法、非溶剂致相分离(NIPS)法和热致相分离(TIPS)法。相比于熔融拉伸法和非溶剂致相分离法,用热致相分离法制备的聚偏氟乙烯微孔膜具有渗透性能好、孔径可调、孔径分布窄和机械性能优异等优点。然而,国内真正商业化生产的热致相分离法聚偏氟乙烯微孔膜并不多,而进口产品的价格又昂贵。因此开展热致相分离法聚偏氟乙烯中空纤维膜的研制以及相关技术问题的研究很有必要。本文基于聚合物溶液相容性原理,以邻苯二甲酸二丁脂(DBP,聚偏氟乙烯强稀释剂)和邻苯二甲酸二辛酯(DOP,聚偏氟乙烯弱稀释剂)混合物作为聚偏氟乙烯膜材料的稀释剂,通过绘制体系的热力学相图和观察体系相分离行为两种方法来确定了聚偏氟乙烯/邻苯二甲酸二丁酯/邻苯二甲酸二辛脂三元体系的相分离行为。综合考察了稀释剂的挥发性、挤出机的操作温度、能耗以及聚偏氟乙烯的降解温度、熔点和浓度,并结合相图,确定了适宜的制膜温度为443-493K。同时,研究了聚合物分子量、聚合物浓度、稀释剂配比和冷却速率对相分离行为和膜形貌与性能的影响。最终确定了较佳的制膜聚合物浓度为35wt%,稀释剂配比为DBP/DOP(wt/wt)为1/2。本文还通过添加纳米碳酸钙颗粒,实现了中空纤维膜机械性能和制膜稳定性的提高,并且通过酸处理后去除纳米碳酸钙,实现了聚偏氟乙烯膜的孔隙率、渗透性能和耐化学性能的改善。
[Abstract]:Polyvinylidene fluoride (PVDF) is a semicrystalline polymer, which is endowed with good thermal stability by crystalline region and flexible by amorphous region. At the same time, polyvinylidene fluoride (PVDF) has good chemical stability. It is not corroded by acid, oxidant and halogen at room temperature, and is stable to organic solvents such as aliphatic hydrocarbon, aromatics, alcohols and aldehydes, and is resistant to 纬-ray and ultraviolet radiation. In recent years, polyvinylidene fluoride (PVDF), as an excellent membrane material, has been more and more recognized by people. The common methods for preparing PVDF microporous membranes include melt stretching, non-solvent induced phase separation (NIPS) and thermally induced phase separation (TIPS). Compared with the melt drawing method and the non-solvent induced phase separation method, the PVDF microporous membranes prepared by thermal phase separation have the advantages of good permeability, adjustable pore size, narrow pore size distribution and excellent mechanical properties. However, there are not many polyvinylidene fluoride microporous membranes produced commercially in China, and the price of imported products is expensive. Therefore, it is necessary to develop thermal phase separation polyvinylidene fluoride hollow fiber membrane and related technical problems. Based on the principle of compatibility of polymer solution, the mixture of dibutyl phthalate (DBP) and dioctyl phthalate (DOP) was used as the diluent of PVDF membrane material. The phase separation behavior of poly (vinylidene fluoride) / dibutyl phthalate / dioctyl phthalate was determined by drawing the thermodynamic phase diagram and observing the phase separation behavior of the system. The volatility of diluent, operating temperature of extruder, energy consumption, degradation temperature, melting point and concentration of polyvinylidene fluoride (PVDF) were investigated, and the optimum film preparation temperature was determined to be 443-493K combined with phase diagram. At the same time, the effects of polymer molecular weight, polymer concentration, diluent ratio and cooling rate on the phase separation behavior, morphology and properties of the film were studied. The optimum polymer concentration is 35 wt.The diluent ratio is DBP / DOP / WT / WT = 1 / 2. The mechanical properties and membrane stability of hollow fiber membrane were improved by adding nano-calcium carbonate particles, and the porosity of polyvinylidene fluoride membrane was realized by removing nano-calcium carbonate after acid treatment. Improved permeability and chemical resistance.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893

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