Development of hollow fiber membrane with organic-inorganic composite structure used for water recycle system

以聚偏氟乙烯（PVDF）/邻苯二甲酸二乙酯为原料，采用热致相分离法（TIPS）制备了PVDF中空纤维膜。熔融温度对膜的结构影响很大。当熔融温度为180℃时，由于聚合物结晶而形成球晶结构，而在150℃时形成互连结构（花边结构）。根据DSC数据讨论了膜结构的形成机理。球晶结构的材料具有较高的透水性和较低的机械强度。另一方面，互连结构表现出较高的强度。考察了粘土的加入对膜性能的影响。粘土的加入有利于形成相互连接的结构。采用非溶剂诱导相分离法（NIPS）制备了PVB-TiO_2复合中空纤维膜。二氧化钛（TiO_2）粒子具有在紫外光照射下使表面亲水的特性。TiO_2的加入对膜的透水性影响不大，但膜的拉伸强度和弹性有所提高。当PVB浓度为10wt%时，TiO_2与PVB的质量比从1变为2。随着TiO_2含量的增加，复合材料的透水性增加。此外，对于所有膜，随着时间的推移，水渗透性增加，并且在约15天后变得恒定。另一方面，拉伸强度和弹性随时间的推移而保持恒定。另外，PVB-TiO_2复合膜经紫外光照射后，膜表面的水接触角减小，表明复合膜表面亲水性增强。

Poly (vinylidene fluoride) (PVDF) hollow fiber membrane was prepared from PVDF/diethyl phthalate system via thermally induced phase separation (TIPS). The melting temperature greatly affected the membrane structure. When the melting temperature was 180℃, spherulite structure due to the polymer crystallization was obtained, while the inter-connected structure (lacy structure) was formed at 150℃. The formation mechanism of the membrane structure was discussed based on the DSC data. The spherulite structure showed the higher water permeability with the lower mechanical strength. On the other hand, the inter-connected structure showed the fairly high strength. The effect of the addition of clay on the membrane performance was also investigated. The addition of clay was useful to form inter-connected structure. The resultant hollow fiber membrane had higher membrane strength and membrane elongation.PVB-TiO_2 composite hollow fiber membranes were prepared via nonsolvent induced phase separation (NIPS) method. Titanium dioxide (TiO_2) particle has the property that makes the surface to be hydrophilic by the irradiation of ultraviolet (UV). Though the water permeability for membranes hardly changed with the addition of TiO_2, the tensile strength and elasticity increased. When PVB concentration is 10wt%, the weight ratio of TiO_2 to PVB changed from 1 to 2. The water permeability increased with the increase of TiO_2 content. Furthermore, for all the membranes, with the elapse of time, the water permeability increased, and it became to be constant after about 15days. On the other hand, tensile strength and elasticity kept constant with the elapse of time. In addition, for PVB-TiO_2 membrane, the water contact angle on the membrane surface decreased after the irradiation of UV, which means that the surface of the composite membrane became to be more hydrophilic.