【作者】 沈立强；

【导师】 徐又一； 徐志康；

【作者基本信息】 浙江大学 ， 高分子化学与物理， 2002， 博士

【摘要】 通过对聚醚酰亚胺(PEI)制膜体系的相分离行为研究，本文以PEI为膜材料制备了中空纤维超滤膜，并通过对PEI的磺化，制备了磺化聚醚酰亚胺(SPEI)/PEI中空纤维共混超滤膜，提高了膜的亲水性能。 首先，结合线性浊点关系(LCP关系)，根据浊点测定实验，通过三元相图研究了PEI制膜体系的相分离行为。研究结果表明：LCP关系可以用于描述PEI/N，N-二甲基乙酰胺(DMAc)/水、PEI/DMAc/乙醇和PEI/DMAc/乙酸三元体系在相分离时的浊点组成，并可以依据LCP关系外推计算三个体系的双节线；对于PEI/(DMAc+乙酸)/水四元体系，发现水和乙酸作为一个组分处理时，体系仍然符合LCP关系；水和乙酸对PEI/DMAc溶液在浊点组成上具有加和性，可以通过PEI/DMAc/水及PEI/DMAc/乙酸体系的LCP关系计算PEI/(DMAc+乙酸)/水体系的浊点组成；根据由LCP关系计算得到的PEI/DMAc/(水+DMAc)、PEI/DMAc/(乙醇+DMAc)及PEI/DMAc/(乙酸+DMAc)体系的双节线发现，当凝固浴中DMAc加入量在50％以上时，体系的双节线偏离DMAc/PEI轴的速度明显加快；随着非溶剂凝固能力的下降，加入DMAc对体系双节线在相图中位置的影响也越来越大。 在对PEI制膜体系的相图研究的基础上，以PEI为原料制备了中空纤维超滤膜。通过对膜结构的扫描电镜(SEM)观察，发现随着内凝固浴中DMAc的加入，PEI中空纤维膜的内表面出现微孔，纤维断面中的孔结构从指状孔向海绵状孔转化。同时，膜的分离性能测试表明随着内凝固浴中DMAc的加入，膜的水通量逐渐下降，截留率变化不大。此外，通过改变纺丝液中PEI浓度制备了中空纤维超滤膜，SEM观察发现，随着PEI浓度的提高，膜中指状孔结构减少，膜变的致密，膜的分离性能测试表明膜的水通量降低，截留率有所提高。同时，随着纺丝液中PEI浓度的提高，中空纤维膜的力学性能也逐步提高。 在PEI制膜液中加入低分子添加剂乙酸，研究了其对PEI中空纤维膜的结构与性能的影响。发现随着乙酸的加入，促进了制膜体系发生旋节相分离，抑制了大孔的形成，膜的水通量也得到提高。通过提高内凝固浴流速，PEI中空纤维膜 摘 要的水通量得到提高，而截留率变化不大。 为了提高PEI膜的亲水性，采用氯磷酸对PEI进行了磺化，在PEI分子中引入磺酸基团，得到了SPEI，并通过红外光谱、核磁共振氢谱、差热分析、热失重、接触角及离子交换容量（IEC）等手段对 SPEI进行了分析。发现 SPEI的玻璃化转变温度高于PEI，热失重温度略低于区I。同时，随着Na型SPEI的IEC提高，其吸水率也随之提高，甚至部分溶于水。用Na型SPEI与PEI共混制备平板膜，发现随SPEI的IEC提高及共混物中SPEI含量提高，膜的亲水性逐渐提高，膜断面的海绵状孔结构的尺寸逐渐变大。研究发现，以 IEC为 2．88m mol电的SPEI与PEI以2用（wt／则比例共混时，膜经碱液中和后，接触角从PEI膜的gi‘降低 为 73’。 得到了亲水性的SP阳后，将SPEI与防I共混，制备了中空纤维超滤膜，研究了共混膜的结构与性能。发现随着制膜液中SPEI的加入，体系发生旋节相分离，大孔的形成受到抑制。改变制膜的空气间隙距离，发现随着空气间隙的增加，中空纤维膜外壁形成微孔并逐渐变大，制膜液发生旋节相分离的趋势减弱。通过对SPE厂P0中空纤维超滤膜的分离性能测试，发现其水通量随着空气间隙距离的增加存在一个最大值，而膜的截留率一直呈下降趋势。通过改变SPEI的添加比例及纺丝的空气间隙距离，得到了水通量为 54．ZI／m’h （．IMPal，对分子量 4万的葡聚糖截留率为78％的中空纤维超滤膜。 通过SPEI／PEI共混膜的牛血清白蛋白（BSA）溶液过滤实验，研究了其抗污染性能。发现随着共混膜中SPEI含量的提高，膜的通量衰减中由于可逆性BSA吸附导致的比例提高，膜变的容易清洗。同时，膜的抗污染性能随BSA溶液pH值的降低而降低。以 IEC为 2．88 m mol／g的 SPEI与 PEI共混制膜，当 SPEI含量为共混物的15 Wt％时，膜的可逆性通量衰减约为乃％。 通过将制备的中空纤维膜经 80吐的水浸泡 12l 小时，研究了膜的耐热性。发现PEI中空纤维膜的水通量及截留率几乎不受影响，而肥E厂PEI共混膜经浸泡后其水通量及截留率均有提高。实验中得到了水通量为 73．sl／m‘hN．IMPaX对分子量4万的葡聚糖截留率为87％的SPEI／PEI中空纤维超滤膜。更多还原

【Abstract】 Polyetherimide (PEI) hollow fiber membranes were prepared by phase inversion method based on the phase separation behavior of PEI dope. Moreover, in order to improve the hydrophilicity of the membrane, PEI was sulfonated and the sulfonated polyetherimide (SPEI) was blended with PEI to prepare membranes.The phase separation behavior of PEI dope was studied according to the linerized cloud point (LCP) correlation. It was found that the phase separation behavior of the three systems, i.e., PEI/DMAc/H2O, PEI/DMAc/ethanol and PEI/DMAc/acetic acid (AA), all agree with the LCP correlation. The binodal lines of the three systems were calculated according to the LCP correlation. The binodal lines of the PEI/DMAc /(H2O+DMAc), PEI/DMAc/(ethanol+DMAc) and PEI/DMAc/(AA+DMAc) systems were also calculated according to the LCP correlation. It was found that the binodal lines of the systems are shifted away the PEI/DMAc axis with the addition of DMAc into the nonsolvent/DMAc mixture. Moreover, the shift of the binodal line is more remarkable when the coagulation ability of the nonsolvent is weaker. Furthermore, because of the additive property for cloud point component, the phase separation of PEI/DMAc/(H2O+AA) system also agrees with the LCP correlation,PEI ultrafiltration (UF) hollow fiber membranes were prepared by phase inversion method and some spinning parameters were investigated. With the addition of DMAc into the internal coagulant solution, micropores are found in the inner surface of the hollow fiber, and formation of the finger-like macrovoid is suppressed in the cross section of the hollow fiber by SEM examination. With higher dope concentration, the pore structure is tighter, and a membrane with higher retention and lower pure water flux is obtained.A A was used as an additive to improve the PEI UF membrane performance. With the addition of AA into the dope solution, spinodal phase separation is induced and the finger-like macrovoid formation is suppressed. In addition, the water flux of themembrane was improved.PEI was sulfonated by chlorosulfonic acid (CSA) in order to impart hydrophilicity to the polymer. With the increase of the CSA/PEI repeat unit ratio and/or reaction time, ion exchange capacity (IEC) of the sulfonated polyetherimide (SPEI) increases accordingly. Water absorption test and contact angle measurement showed that the hydrophilicity of the SPEI increases with the increasing of IEC. Membranes were fabricated from SPEI/PEI blend with different ratios. The morphologies of the blend membranes were observed by SEM. It was found that the membrane pore size became larger when SPEI with higher IEC was used. With the increasing of SPEI ratio in the blend membranes, the membrane pore size increased, too. The contact angle data of the membranes showed that the hydrophilicity of the blend membrane was elevated because of the sulfonate group on the SPEI molecular chain. At last, a blend membrane with contact angle of 73?was obtained, in contrast to 91?for the PEI membrane.SPEI was blend with PEI to prepare hollow fiber UF membranes and several spinning parameters were investigated. With the addition of SPEI, spinodal phase separation was observed. Increasing the air gap distance, micropores were found in the outer fiber surface and the pore size was larger with longer air gap distance. The tendency to induce spinodal phase separation was suppressed at longer air gap distance. The water flux of the membrane showed a maximum with different air gap distance and the retention decreased with increasing of air gap distance. A SPEI/PEI hollow fiber membrane with water flux of 54.2 1/m2 h (0.1 MPa) and 78% retention of dextran (Mw=40 000) solution was obtained.The filtration of Bovine serum albumin (BSA) solution was carried out in order to examine the fouling tendency of the SPEI/PEI blend membranes. With increasing the SPEI ratio in the blend membrane, the membrane flux lost due to the reversible adsorption of BSA increases, and the BSA adhered to the membrane surface is more easily washed更多还原