聚醚砜中空纤维膜的成形条件与形态结构研究

采用扫描电镜探讨经双向拉伸聚醚砜(PES)中空纤维膜的纺制工艺条件与结构之间的关系。在膜的中部通入填充液,随着填充液压力的增大,中空纤维膜的壁厚明显减小,同时纤维膜表面的孔明显增多。随着凝固浴质量分数的增加,中空纤维膜表面的孔径先减小后增大,而中空纤维膜接近外表面的皮层逐渐变厚。随着凝固浴拉伸率的提高,中空纤维膜在外径不变的情况下壁厚减小,内表面积增加;纤维变薄而且更为致密。     

聚醚砜中空纤维膜的制备

讨论了在二次成形聚醚砜(PES)中空纤维膜的制备中,PES浓度和不同的填充液对中空纤维膜结构和性能的影响。结果发现:随着PES浓度的增大,中空纤维膜的水通量呈下降的趋势,确定了二次成形PES中空纤维膜制备中PES最佳浓度为24%;不同填充液与溶剂之间的相互扩散速率不同,得到了具有不同结构的聚醚砜中空纤维膜。随着填充液压力的提高,纤维的内径、外径增加,壁厚减小,水通量增大,一般填充液压力为0.020MPa。     

双向拉伸法制备聚醚砜中空纤维

采用双向拉伸的方法制备了聚醚砜中空纤维,探讨了工艺条件对聚醚砜中空纤维取向度和水通量的影响。结果表明:随着纺丝速度的提高,纤维的取向度上升,水通量下降;在总拉伸倍数不变的前提下,随着凝固浴拉伸倍数的提高,纤维的取向度和水通量都减小;随着填充液压力的提高,纤维的取向度下降,水通量增加;随着凝固浴中二甲基亚砜含量的提高,纤维的取向度先增大后减小,出现了一个最大值,水通量先减少后增加,出现了一个最小值。     

凝固浴质量分数对聚醚砜中空纤维膜结构和性能的影响

采用干喷湿纺法纺制成聚醚砜中空纤维膜,研究了凝固浴质量分数与PES中空纤维结构和性能之间的关系。结果表明：在凝固浴质量分数10％～40％的范围内,中空纤维膜的水通量先减少再增加;中空纤维的取向度则先增大后减小;膜表面孔的数量及孔径都有一个先减后增的现象。     

聚醚砜中空纤维血浆分离膜的孔径大小及分布

本文采用场致扫描电镜的显微观察法和膜对溶质的粒子筛分法测定聚醚砜中空纤维血浆分离膜的孔径大小及分布。通过显微镜观察统计得到膜的几何平均孔径为229nm,膜孔孔径分布在150nm,-350nm,筛分法测试得到膜的平均孔径为197nm。平均孔径大小约为200nm的聚醚砜中空纤维膜适合做血浆分离膜。     

非溶剂添加剂对聚醚砜酮中空纤维纳滤膜结构和性能的影响

以新型杂萘联苯聚醚砜酮(PPESK)为膜材料,N-甲基-2-吡咯烷酮(NMP)为溶剂,乙二醇甲醚(EGME)、冰醋酸(AA)以及AA/EGME作为复合添加剂,采用干-湿相转化技术制备了中空纤维非对称纳滤膜,重点考察了非溶剂添加剂对中空纤维膜结构和性能的影响。结果表明非溶剂添加剂的加入导致了中空纤维膜孔结构由指状转变为海绵状,从而引起中空纤维膜性能的变化。当聚合物质量分数为23%,铸膜液溶剂体系为m(AA)∶m(EGME)∶m(NMP)=5.7∶16.5∶54.8时,中空纤维膜对PEG600的截留率高于96%,纯水通量为211 L/(m2.h)。     

非溶剂添加剂对聚醚砜中空纤维膜的结构调控

采用非溶剂致相分离法,以聚醚砜(PESU)为膜材料、N,N-二甲基乙酰胺(DMAc)为溶剂、水为非溶剂添加剂、聚乙烯吡咯烷酮(PVP)为改性致孔剂,纺制了不同非溶剂水含量(质量分数)以及不同湿态壁厚的PESU中空纤维膜,通过改变纺丝溶液配方中水含量和膜丝湿态壁厚来研究中空纤维膜结构的调控机制,考察了膜丝的外表面孔径及分布、内部孔隙率、干燥收缩比、爆破压力等参数。结果表明,纺丝溶液配方中水含量的提升以及湿态壁厚的增加均可以增大膜丝外表面平均孔径,在湿态壁厚为60 μm、水含量为7%时,可以使得中空纤维膜外表面平均孔径达到最大值0.557 2 μm,相较于湿态壁厚45 μm、水含量0%时的外表面孔径0.267 4 μm,增加了约108.4%;同时,随着水含量从0%提升至7%,膜丝的内部从相对松散的海绵状孔结构趋于形成更加致密的海绵状孔结构,膜丝孔隙率从90.1%下降到79.9%,平均干燥收缩比从25.2%下降到16.3%,爆破压力从0.34 MPa升高至0.44 MPa。     

聚醚砜纤维及织物性能研究

将聚醚砜(PES)进行熔融纺丝,制得PES纤维,并织成布样,对纤维及其织物的性能进行了研究。结果表明:PES纤维的力学性能不稳定,放置一定时间,其强度下降,需经140℃高温热定型加以改善。纤维回潮率为2．33%;织物极限氧指数为26．9%,紫外吸光度低于1．6,体积比电阻为8．13×10~(13)Ω·cm,摩擦静电压为7 272 V,1 min后衰减电压为5 519 V。     

聚苯硫醚纤维与聚醚砜纤维的结构与性能

分别以聚苯硫醚(PPS)、聚醚砜(PES)切片为原料,在一位4头的熔融纺丝实验机上,制备了PPS及PES纤维,并对两者结构与性能的差异进行比较。结果表明:PPS和PES的初生纤维都具有光滑的表面,PES的流动性能比PPS差,表观黏度也比PPS要大;PPS纤维的玻璃化转变温度为90¹00℃,结晶温度为130.09℃,熔融温度为279.56℃,初始热分解温度为500℃,半寿温度为625℃;PES纤维的玻璃化转变温度为225℃,初始热分解温度为460℃,半寿温度为600℃,没有结晶温度和熔融温度;PPS纤维为半结晶聚合物,结晶速率为0.045 s-1,而PES纤维属于无定形或极低结晶度材料;PES纤维和PPS纤维都具有优异的热稳定性和阻燃性,都非常适合应用在阻燃及耐高温场合。     

高性能中空纤维超滤膜结构和性能研究

以含二氮杂萘酮结构的聚醚砜酮(PPESK)为膜材料,N-甲基-2-吡咯烷酮为溶剂,一缩二乙二醇、乙二醇甲醚和丁酮为添加剂,采用干-湿相转化技术制备了中空纤维非对称超滤膜。结果表明,聚合物浓度、添加剂类型和添加剂浓度的变化导致了超滤膜的形态逐渐由长而宽的指状孔结构变为海绵状结构,同时也对超滤膜的性能产生了较大的影响,所制得的PPESK超滤膜在0 1MPa的操作压力下对PEG10000的截留率高于95%,纯水通量可高达约159L/(m2·h)。     

Preparation of poly(phthalazinone ether sulfone ketone) hollow fiber membrane for gas separation

Poly(phthalazinone ether sulfone ketone) (PPESK) asymmetric hollow fiber membranes for gas separation were prepared by dry/wet phase inversion technique. The effects of various preparation conditions such as solvent, nonsolvent-additives(NSA), PPESK concentration, and air gap on the membrane performance were studied. The heat resistance of the PPESK hollow fiber membrane was also examined. The hollow fiber membrane prepared from solvent with stronger solubility showed low gas permeation and high O₂/N₂ selectivity due to the denser skin layer. Hollow fiber membrane made from PPESK/DMAc/EtOH/THF system had thicker skin layer than that made from PPESK/DMAc/GBL system with the same ratio of near-to-cloud-point of NSA, which resulted in the higher O₂/N₂ selectivity. Along with the increase of NSA content, the gas permeation increased and the O₂/N₂ selectivity decreased. The O₂/N₂ selectivity of hollow fiber membranes made from PPESK/DMAc/GBL and PPESK/DMAc/EtOH/THF systems were 4.9 and 4.8 respectively, when the membrane forming systems contained appropriate content of NSA. The high polymer concentration resulted in low gas permeation and high O₂/N₂ selectivity. When the air gap was excessively long, the membrane performance dropped because of the damage to the dense skin layer. There was no significant drop on the membrane performance when the operation temperature was elevated to 90°C. The average O₂/N₂ selectivity was higher than 3.0 at 70°C during a long period of 55 days' test time. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Continuous phenol biodegradation at high concentrations in an immobilized‐cell hollow fiber membrane bioreactor

Phenol degradation at high concentrations was investigated under continuous operation in an immobilized‐cell hollow fiber membrane bioreactor. Pseudomonas putida ATCC49451 was immobilized in asymmetric polysulfone hollow fiber membranes through entrapment within the porous regions and through attachment on the membrane surfaces. Bioreactor performance was assessed based on the startup period, the effect of feed rate (ranging from 21 to 120 mL/h), the relative contribution of the lumen and the shell sides to phenol degradation, the effect of feed phenol concentration (1000–2000 mg/L) and the long‐term operation of the bioreactor. The bioreactor startup was very short, and steady state was accomplished within 160 h. An optimum degradation capacity with respect to phenol loading rate was observed because of the tradeoff in the amount of phenol degraded against the increase in feed rate. It was also found that at higher feed rate, the shell side contributed to a larger proportion of the total phenol degraded compared with the lumen. On the basis of these results, it was found that options abound for the operating conditions of the bioreactor. These can be chosen depending on whether complete phenol degradation or high degradation capacity is desirable. Finally, long‐term sustainable continuous operation of the bioreactor was demonstrated without significant biofilm fouling on the membranes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of PES on the morphology and properties of proton conducting blends with sulfonated poly(ether ether ketone)

Development of alternate materials to Nafion, based on ionically conducting polymers and their blends is important for the wider applications of proton exchange membrane fuel cells. In this work, blends of sulfonated poly(ether ether ketone) (SPEEK) with poly(ether sulfone) (PES) are investigated. SPEEK with various ion exchange capacity (IEC) was prepared and blended with PES, which is nonionic and hydrophobic in nature. A comparative study of the water uptake, proton conductivity, and thermo‐mechanical characteristics of SPEEK and the blend membranes as a function of the IEC is presented. Addition of PES decreases the water uptake and conductivity of SPEEK. Chemical and thermal stability and mechanical properties of the membrane improve with the addition of PES. The effect of water content on the thermo‐mechanical properties of membranes was also studied. The morphology of blend membranes was studied using SEM to understand the microstructure and miscibility of the components. On the basis of the results, a plausible microstructure of the blends is presented, and is shown to be useful in understanding the variation of different properties with blending. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and performances of poly(phthalazinone ether sulfone ketone) hollow fiber membranes with excellent thermotolerance

The cloud points of PPESK/NMP/H₂O ternary system at different temperatures were measured by titrimetric method. The binodal lines in the ternary phase diagram of the poly(phthalazinone ether sulfone ketone (PPESK) dope system was determined, on the basis of the cloud point experimental data being linearly fitted with the semiempirical linear cloud point correlation. Furthermore, phase separation behavior during the phase inversion of PPESK membrane‐forming system was discussed in terms of the phase diagram. Then, dry–wet spinning technique was employed in manufacturing PPESK hollow fiber membranes by immersion precipitation method. The cross‐section morphologies of hollow fibers were observed by scanning electronic microscopy. Also, the effects of dope solution composition and spinning parameters, including the coagulant composition and the spinning temperature on the separation performances of fibers, were evaluated by permeability measurements. The thermotolerance of the PPESK hollow fiber membranes prepared in the work was examined for the permeation operation at different temperatures and pressure differences. The experimental results showed that pure water flux increases several fold along with the temperature increases from 20 to 80°C at different operation pressures, while the solute rejection only decreases slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 878–884, 2006     

Thermal,crystalline, and tribological properties of PEEK/PEI/PES plastics alloys

PEEK/PEI/PES plastics alloys in weight ratios of 70/30/0, 70/25/5, 65/30/5, 60/30/10, 60/35/5, and the three kinds of single high performance engineering plastics 100/0/0, 0/100/0, 0/0/100 were prepared by twin‐screw extrusion molding. A single glass‐transition temperature (T_g) of each alloy in the former five kinds of the plastics alloys could be measured by DSC and always rose to higher one than that of the pure PEEK by about 20°C. The crystalline degrees of these alloys could also ascended to more than 35.81% higher than that of the pure PEEK, especially for the alloy of the ratio 60/30/10 reached the maximum crystalline degree 37.76%. Adding PEI or PEI and PES, the crystalline temperatures of the PEEK alloys were decreased. The wear resistances of the alloys under dry sliding condition were considerably improved compared with pure PEI or PES, and the specific wear rate of the pure PEI or PES were four to six times as large as that of the alloys. However, the specific wear rates of the alloys were six to eight times larger than that of the pure PEEK, and the friction coefficients of the alloys were higher than that of the pure PEEK for 0.2–0.3. The polymeric transferred film on the steel ring surface against the alloys could be found, but no film on that against pure PES or PEI was found. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Pore structure and properties of poly(ether ether ketone) hollow fiber membranes: influence of solvent‐induced crystallization during extraction

Poly(ether ether ketone) (PEEK) hollow fiber membranes were prepared by a thermally induced phase separation method with polyetherimide as diluent, and N‐methyl pyrrolidone (NMP), dichloromethane and a composite extractant composed of NMP, ethanolamine and water as extractant. The effects of the different solvents induced crystallization on the pore structure during extraction and the properties of the PEEK hollow fiber membranes were investigated in detail. The crystallization behaviors of the membranes were characterized by DSC and XRD. The effect of the extractants on the microscopic morphologies, pore structures, water fluxes and mechanical properties of the membranes were investigated. The results showed that the extraction ability of the composite extractant was the most significant, followed by NMP and dichloromethane. The crystallinity of the hollow fiber was 39.0% before extraction and was elevated to 39.2% after the extraction with NMP, 46.6% with dichloromethane and 46.7% with the composite extractant, which shows that dichloromethane and the composite extractant have strong ability to induce the crystallization of PEEK. The inner and outer surfaces of the membranes obtained after extraction by the composite extractant had the largest pore size and the highest surface porosity. The most probable pore diameter of the membranes obtained after extraction by NMP, dichloromethane and the composite extractant was 23.26 nm, 24.43 nm and 24.43 nm, respectively, which indicated that solvent‐induced crystallization was beneficial for the formation of larger pores. The pure water flux of the PEEK membrane prepared by the composite extractant was the largest, but the tensile strength was the lowest. © 2019 Society of Chemical Industry