热致相分离法PVDF微孔制备与性能研究

发布时间：2018-04-26 01:27

本文选题：聚偏氟乙烯 + 热致相分离法　；参考：《天津工业大学》2017年硕士论文

【摘要】：聚偏氟乙烯(PVDF)是一种性能优良的半结晶性聚合物,具有机械强度高、热稳定性好、耐化学性和高疏水性等优点。作为一种广受关注的膜制备聚合物原料,PVDF目前已被广泛应用于超微滤膜制备,其所制备的膜已被应用于饮用水净化、工业及市政污水处理、膜蒸馏、生物燃料回收以及聚合物电池等多个领域。与传统非溶剂致相分离法(NIPS)相比热致相分离法(TIPS)制得的膜具有强度高、孔隙率高、孔径分布窄等优点。本文以PVDF为成膜聚合物,采用TIPS法制备了 PVDF多孔膜,并对其结构与性能进行了研究。以邻苯二甲酸二丁酯(DBP)与已二酸二辛脂(DOA)组成混合稀释剂,通过TIPS法制备了 PVDF平板膜。研究了稀释剂配比、固含量变化以及无机粒子对膜微观结构与性能的影响。结果表明,PVDF/DBP/DOA成膜体系以S-L相分离为主,呈典型的球晶结构。随PVDF浓度和混合稀释剂中DOA比例增加,膜横截面球晶结构尺寸及球晶结构晶粒间空隙均变小,同时膜表面孔隙率减小,致密度增加。此外,混合稀释剂中DOA比例增加,能够改善膜力学性能,但会减小膜纯水通量。无机添加剂纳米Si02的添加,可明显降低膜孔隙率,提高膜疏水性和断裂强度。以DBP和邻苯二甲酸二辛酯(DOP)组成混合稀释剂,以纳米Si02、石墨烯为添加改性剂,采用TIPS法制备了 PVDF中空纤维杂化膜。结果表明,所得膜为均质海绵状孔结构,外表面较光滑孔径较小,内表面粗糙且疏松多孔,随纳米Si02添加量的增加膜横截面孔径、断裂强度与断裂伸长率均呈先增大后减小的趋势。石墨烯以片层形式均匀分散在膜内,添加石墨烯后膜纯水通量增加,膜孔隙率高于70%。同时加入3wt%纳米Si02与0.5wt%石墨烯所制备中空纤维杂化膜渗透性能较好,纯水通量可达418L/m2·h,力学能较单一组分添加剂所制备中空纤维杂化膜有所改善。
[Abstract]:Polyvinylidene fluoride (PVDF) is a kind of semi-crystalline polymer with excellent properties, such as high mechanical strength, good thermal stability, chemical resistance and high hydrophobicity. As a kind of membrane preparation material, PVDF has been widely used in ultrafiltration membrane preparation, which has been used in drinking water purification, industrial and municipal wastewater treatment, membrane distillation. Biofuel recovery and polymer batteries and other areas. Compared with the traditional non-solvent induced phase separation method (NIPS), the membrane prepared by thermal phase separation method has the advantages of high strength, high porosity and narrow pore size distribution. In this paper, PVDF porous membranes were prepared by TIPS method using PVDF as film forming polymer. The structure and properties of PVDF porous membranes were studied. Dibutyl phthalate (DBP) and dioctyl adipate (DOAA) were used as diluents to prepare PVDF flat membrane by TIPS method. The effects of diluent ratio, solid content and inorganic particles on the microstructure and properties of the film were studied. The results show that the membrane forming system of PVDF / DBP / DOA is dominated by S-L phase separation with typical spherulite structure. With the increase of the concentration of PVDF and the proportion of DOA in the mixed diluent, the size of the spherulite structure and the voids between the spherulites become smaller, while the porosity of the film surface decreases and the density increases. In addition, the increase of the ratio of DOA in the mixed diluent can improve the mechanical properties of the membrane, but reduce the pure water flux of the membrane. The addition of inorganic additive nanometer Si02 can obviously reduce the membrane porosity and improve the hydrophobicity and fracture strength of the membrane. The hybrid membrane of PVDF hollow fiber was prepared by TIPS method using DBP and dioctyl phthalate (DOP) as a mixed diluent and nano-Si _ (02) and graphene as modifiers. The results show that the membrane is homogeneous and spongy, the outer surface is smaller than the smooth pore size, the inner surface is rough and porous, and the cross-section pore size of the membrane increases with the increase of nano- content. The fracture strength and elongation showed a trend of first increasing and then decreasing. Graphene was uniformly dispersed in the membrane in the form of lamellar, and the pure water flux of the membrane increased with the addition of graphene, and the membrane porosity was higher than 70. At the same time, the hollow fiber hybrid membrane prepared by adding 3wt% nanometer Si02 and 0.5wt% graphene has good permeability and pure water flux up to 418L/m2 h. The mechanical properties of the hybrid membrane are better than that prepared by single additive.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

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