【作者】 朱思君；

【导师】 王庆瑞；

【作者基本信息】 东华大学 ， 材料学， 2006， 博士

【摘要】 在对聚醚砜(PES)制膜体系的相分离行为和对PES／二甲基乙酰胺(DMAc)体系流变性能研究的基础上，本文以PES为主要膜材料制备了平板膜和中空纤维膜，并通过共混，制备了酚酞基聚醚砜(PES—C)／PES平板膜和中空纤维膜，提出了PES／PES-C共混膜表层成孔机理。一、研究了聚醚砜／溶剂／非溶剂体系相分离行为结合线性浊点关系(LCP关系)，根据浊点测定实验，通过三元相图研究了PES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PES／DMAc／水和PES／DMAc／1，2丙二醇三元体系在相分离时的浊点组成，并可以依据LCP关系外推计算二个体系的双节线；对于PES／(DMAc+1，2丙二醇)／水四元体系，发现水和1，2丙二醇作为一个组分处理时，体系仍然符合LCP关系；水和1，2丙二醇对PES／DMAc溶液在浊点组成上具有加和性，可以通过PES／DMAc／水及PES／DMAc／1，2丙二醇体系的LCP关系计算PES／(DMAc+1，2丙二醇)／水体系的浊点组成；根据由LCP关系计算得到的PES／DMAc／(水+DMAc)和PES／DMAc／(1，2丙二醇+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／PES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。二、研究了PES／DMAc溶液的流变性能在所研究溶液的浓度范围内(18％～28％)，PES溶液属于切力变稀流体，随着PES浓度的增加，非牛顿指数降低，零切粘度上升。给出了零切粘度与浓度的关系式。讨论了温度对流变性的影响，在所研究的温度范围内(20℃～100℃)，随着溶液温度的升高，非牛顿指数上升，零切粘度降低。由零切粘度与铸膜液温度之间的关系，根据Arrhenius方程计算出了溶液的粘流活化能。三、研究了PES平板膜和中空纤维膜的成形、结构和性能及其相互关系以PES为主要材料，以1，2丙二醇为制膜液的低分子添加剂，聚乙二醇为制膜液的大分子添加剂，制备平板膜以研究制膜液浓度、添加剂、预蒸发时间、凝固浴组成等制膜工艺条件对膜的结构与性能的影响。纺制中空纤维膜以研究内凝固浴组成、内凝固浴压力和外凝固浴中溶剂浓度等制膜条件对膜的结构与性能的影响。实验结果表明：随着铸膜液浓度的上升，PES平板膜的水通量、孔隙率和平均孔径总体呈下降的趋势；而膜对牛血清白蛋白的截留率则上升。随着低分子添加剂1，2-丙二醇添加量的增加，PES平板膜的水通量和平均孔径呈上升趋势；而孔隙率没有明显的变化；随着1，2-丙二醇添加量的增加，膜对的牛血清白蛋白的截留率先上升，然后再下降。大分子添加剂PEG作为致孔剂可以改变膜孔的大小、数量，进而改变膜的性能。随着PEG添加量的上升，PES平板膜的水通量、孔隙率和平均孔径均呈上升趋势。截留率则随着添加量的增加，先增加，当PEG添加量较多(＞3％)时，截留率随PEG添加量增加而下降。随着预蒸发时间的延长，PES平板膜的水通量略有上升，孔隙率变化不明显，平均孔径略有增加。截留率先是略有降低而后呈升高的趋势。随着凝固浴温度的上升，PES平板膜的水通量、平均孔径和孔隙率都呈上升的趋势，截留率下降。随凝固浴中DMAc含量的增加，PES平板膜的水通量、孔隙率和平均孔径下降，截留率上升。随着内凝固浴压力的提高，PES中空纤维膜的内、外径增加，壁厚减小，水通量、膜孔隙率和平均孔径增大，中空纤维膜对牛血清蛋白的截留率则呈逐渐下降的趋势。随着外凝固浴浓度的增大，纤维的内外径和厚度基本不变，而PES中空纤维膜的外径与内径之比也没有规律性的变化；膜的水通量、孔隙率和平均孔径先下降后增大，在外凝固浴浓度为20％出现一个最小值，截留率则先增大后下降，在外凝固浴浓度为20％出现一个最大值。四、研究了聚醚砜／酚酞基聚醚砜相容性及共混溶液的流变性能采用稀溶液粘度法和相差显微镜等手段探讨了聚醚砜(PES)与酚酞基聚醚砜(PES-C)的相容性，讨论了聚醚砜／酚酞基聚醚砜共混浓溶液的流变性。实验结果表明：PES／PES-C是一个在任意配比下都具有动力学稳定性的体系，在其共混比为1左右时，PES／PES-C体系又具有热力学不稳定性。在共混比为1左右时，PES／PES-C体系既可以获得澄清透明的铸膜液又能在成膜过程中产生相分离。共混溶液的非牛顿指数均小于1，并随着PES与PES-C比例的变化而变化。随着PES与PES-C比例的接近，两者相容性的变化导致非牛顿指数不断增加，在PES／PES-C=1：1时出现了最大值。共混溶液的零切粘度随PES—C含量的增加，溶液的零切粘度逐渐增大。在共混比例为1：1时，随溶液浓度的增加，非牛顿指数逐渐减小，更加偏离牛顿流体。在共混比例为1：1时，共混溶液的零切粘度与总固浓度之间具有较高的浓度依赖性。共混溶液的非牛顿指数随温度的上升而上升并逐渐趋近于1。根据Arrhenius方程计算出了共混比为1：1时，不同浓度的粘流活化能，由结果可知随溶液浓度的增加，E_η的值增加，且共混比为1：1共混溶液粘流活化能的值介于PES溶液和PES-C溶液的粘流活化能值之间。五、研究了PES／PES-C共混膜成形、结构和性能及其影响因素将PES与PES-C共混制备平板膜和中空纤维膜，研究了PES与PES-C的共混比及其它因素对共混膜结构和性能的影响，提出了PES／PES-C共混膜表层成孔机理。实验结果表明：与单组分聚合物膜的规律相似，随着铸膜液中聚合物总浓度的上升，PES／PES-C共混膜的水通量、孔隙率和平均孔径呈下降的趋势；而膜对牛血清白蛋白的截留率则呈现上升的趋势。无论平板膜还是中空纤维膜，即随着铸膜液中PES与PES-C共混比接近于1，膜水通量、孔隙率和平均孔径呈现上升的趋势而截流率下降。随着铸膜液温度的上升，水通量、孔隙率和平均孔径呈现下降的趋势，而膜对牛血清白蛋白截流率逐渐上升。根据实验现象，提出了PES／PES-C共混膜表层成孔机理，可应用此膜表层孔的形成机理，共混时选择不同比例的PES／PES-C及不同的铸膜液温度，以此调节相容性，控制膜的孔径和孔隙率，制备不同性能和用途的膜。更多还原

【Abstract】 In this work, the phase separation behavior and the rheological properties of thecasting solution of Polyethersulfone （PES） prepared with dimethyI lacetamide（DMAc） were studied, and PES flat-sheet membranes and hollow fiber membraneswere prepared. Moreover PES and Phenolphthalein polyethersulfone（PES-C） wereblended, and PES/ PES-C blend membranes including flat-sheet membranes andhollow fiber membranes were prepared, The mechanism about pores forming on theskin layer of PES/PES-C blend membranes is put forward.The research is as follows:1. The phase separation behavior of PES/DMAc/nonsolvent systems wasinvestigated.The phase separation behavior of PES dope was studied according to the linerizedcloud point （LCP） correlation. It was found that the phase separation behavior of thetwo systems, i.e., PES/DMAc/H₂O and PES/DMAc/C₃H₆（OH）₂, both agree with theLCP correlation. The binodal lines of the two systems were calculated according tothe LCP correlation. The binodal lines of the PES/DMAc/（H₂O+DMAc） andPES/DMAc/（C₃H₆（OH）₂+DMAc） systems were also calculated according to the LCPcorrelation. It was found that the bimodal lines of the systems shifted away the PES/DMAc axis with increasing the content of DMAc into the nonsolvent/DMAc mixture.Moreover the shift of the binodal line is more remarkable when the coagulationability of the nonsolvent is weaker. Furthermore, the phase separation behavior ofPES/DMAc/（H₂O+C₃H₆（OH）₂） system also agrees with the LCP correlation, and theeffects of H₂O and C₃H₆（OH）₂ on the composing of cloud point are additive.2. The rheological properties of PES/DMAc solutions were investigated.The solution behaves shear-shinning characteristics within the concentration studiedfrom 18% to 28%. Non-Newtonian index decreases and the zero shear viscosityincreases with increasing the concentration of PES. Dependence of zero shear viscosity on concentration of PES is formulated. Non-Newtonian index increases andthe zero shear viscosity decreases with solution temperature rising from 20℃to 100℃. The viscous flow activation energy is calculated after Arrhenius equation.3. The structure and properties of PES flat-sheet membranes and hollow fibermembranes were investigated.The PES membranes prepared from the casting solution containing low molecularweight additive such as propylene glycol and high molecular weight additive such aspolyethylene glycol （PEG）. The effects of the concentration of casting solution,additives, pre-vaporizing time, the composing of coagulation bath on the structureand properties of PES flat-sheet membranes and hollow- fiber membranes werestudied. Moreover the effects of the composing and pressure of coagulation bathinside hollow fiber membranes and the concentration of coagulation bath outerhollow fiber membranes on the structure and properties of PES hollow fibermembrane were also studied.For PES flat-sheet membranes, the pure water flux, porosity and average pore sizesdecrease, and retention to bovine serum albumin （BSA） increases with increasing theconcentration of PES. The pure water flux and average pore sizes increases, porositychanges little, and the retention to BSA reaches the maximum with increasing theconcentration of low molecular weight additive, propylene glycol. The sizes andamount of pores on the membranes are changed when high molecular weight additivesuch as PEG is added in the casting solution so that the properties of membrane arealso changed. The pure water flux, porosity and average pore sizes increase and theretention to BSA reaches the maximum when the concentration of PEG is 3% withincreasing the concentration of PEG. The pure water flux and average pore sizesincrease slightly and porosity changes little, and the retention to BSA reaches themaximum with extending pre-vaporizing time. The pure water flux, porosity andaverage pore sizes increase and the retention to BSA decreases with increasing theconcentration of DMAc in the casing solution. For PES hollow fiber membranes, the inner diameter and outer diameter of hollowfiber membranes increase, the thickness of wall decreases, the pure water flux,porosity and average pore sizes increase and the retention to BSA decreases withincreasing the pressure of coagulation bath inside hollow fiber membranes. The innerdiameter, outer diameter and thickness of wall of hollow fiber membranes changelittle, the pure water flux, porosity and average pore sizes reaches the minimum andthe retention to BSA reaches the maximum when the concentration of coagulationbath outer hollow fiber membranes is 20% with increasing the concentration ofcoagulation bath outer hollow fiber membranes.4. The compatibility and rheological properties of PES/PES-C blend solutions wereinvestigated.The compatibility of PES/PES-C blend solutions was investigated by dilute solutionviscometry and phase difference microscope method. The results show that PES/PES-C blend system is miscible at any blend ratios. But the system is instable whenblend ratio of PES and PES-C is 1.The rheological properties of PES /PES-C blend solutions were investigated. Theblend solution behaves shear-shinning characteristics. Non-Newtonian increases andreaches the maximum when the blend ratio of PES and PES-C is 1. The zero shearviscosity of blend solutions increases with increasing the concentration of PES-C.Non-Newtonian index decreases and the zero shear viscosity increases when blendratio is 1 with increasing the concentration of blend solutions, and the dependence ofzero shear viscosity on concentration is formulate& The viscous flow activationenergies at different concentrations of blend solutions are calculated after Arrheniusequation.5. The structure and properties of PES/PES-C blend membranes were investigated.PES and PES-C were blended to prepare PES/ PES-C blend membranes includingflat-sheet membranes and hollow fiber membranes. The effects of the blend ration ofPES and PES-C and other factors on the structure and properties of PES/PES-C blend membranes are studied. The mechanism about pores forming on the skin layer ofPES/PES-C blend membranes is put forward.For PES/PES-C blend membranes including tim-sheet membranes and hollow fibermembranes, the pure water flux, porosity and average pore sizes decrease and theretention to BSA increases with increasing the concentration of blend solution. Thepure water flux, porosity and average pore sizes increases and the retention to BSAdecreases with increasing the blend ratio of PES and PES-C until it is close to 1. Thepure water flux, porosity and average pore sizes decreases and the retention to BSAincreases with the temperature of blend solution rising.The mechanism about pores forming on the skin layer of PES/PES-C blendmembranes is put forward after the experimental data. The blend ratio of PES andPES-C and temperature of the casting solution after the mechanism could be changedto adjust compatibility of blend solution, the pore sizes and porosity of membranes sothat the membranes with different properties and applications are prepared.Zhu Sijun （Material Science and Technology）Supervised by Prof. Wang Qingrui更多还原