热致相分离法制备聚酰胺纤维增强PAN中空纤维膜研究

以聚丙烯腈(PAN)为基体材料,聚酰胺纤维为增强材料,采用热致相分离法制备了聚酰胺纤维增强PAN的中空纤维膜,观察了中空纤维膜的微观结构,并研究了混合稀释剂、PAN及聚酰胺纤维对中空纤维膜性能的影响.结果表明:中空纤维膜表层分子排列致密,分离层存在纤维状孔隙结构;PAN与聚酰胺纤维的相容性良好;混合稀释剂用量为10％(...     

热致相分离法iPP/nano-SiO2杂化中空纤维膜的结构与透过性能

通过熔融共混等规聚丙烯(iPP)/邻苯二甲酸二丁酯(DBP)/邻苯二甲酸二辛酯(DOP)/纳米二氧化硅(nano-SiO2)体系,采用热致相分离法(TIPS)制备了iPP中空纤维膜。对膜结构与透过性能进行了表征。用示差扫描量热仪(DSC)测定了体系的iPP动态结晶温度,融化峰值温度数值表明结晶只存在α晶型。X光电子能谱(XPS)表明nano-SiO2向膜表面发生了迁移,使得膜的亲水性有所提高,膜的接触角由120.05°降低到101.05°,降低了19.7%。随着nano-SiO2添加量的增加,膜的孔隙率和纯水通量均呈现先增大后减小的趋势。膜的孔隙率增加了20.2%,纯水通量增大了21.7%。经过拉伸后的杂化膜,孔隙率增大了27.4%,纯水通量增加了211%。研究表明:通过向铸膜液中添加nano-SiO2,可以优化膜结构,并改善膜的亲/疏水性以及透过性能。     

热致相分离制膜方法的研究及应用进展

本文综述了热致相分离法制备微孔膜的最新研究进展.首先介绍了热致相分离法的成膜机理,其次逐一重点阐述了聚合物和稀释剂不同体系对所制备膜的结构和性能的影响,并就这种方法所制备的微孔膜在不同领域中的应用进行了介绍.最后指出,制造精确化可控的膜结构有利于膜的高效广泛应用,未来绿色、高性能膜的发展将会是研究的重点.     

稀释剂极性对TIPS法制备聚丙烯中空纤维膜的影响

以聚丙烯(PP)为原料,以极性低和极性高的两种溶剂作为复配稀释剂,用热致相分离法(TIPS)制备PP中空纤维膜,利用称重法计算孔隙率,利用自制通量装置测试气通量。结果表明,稀释剂极性对膜结构和性能影响较大,极性高的溶剂含量为6.67份时,孔隙率和气通量最大,分别为78.29%和211.2 m3/(m2?h)。用扫描电镜对膜的形貌结构进行了研究,讨论了膜的力学性能。     

稀释剂对热致相分离法制备聚偏氟乙烯膜结构的影响

以聚偏氟乙烯(PVDF)和一种在常温下为固态的水溶性潜溶剂己内酰胺(CPL)为膜材料和稀释剂,基于热致相分离原理,制备了PVDF微孔膜,通过差示扫描量热仪对不同条件下二元共混物的结晶性能进行了分析,利用扫描电镜研究了稀释剂含量对膜微观结构的影响。结果表明,PVDF质量分数小于25%,PVDF/CPL高温溶液体系在降温过程中发生液-液相分离,主要形成了双连续网络孔结构。研究了PVDF浓度对膜水通量、BSA截留率、膜强度等的影响,该研究为用单一水溶性稀释剂制备PVDF微孔膜定了基础。     

混合稀释剂对热致相分离法制备聚偏氟乙烯膜性质及结构的影响

采用邻苯二甲酸二丁酯(DBP)为稀释剂,通过加入部分N,N-二甲基乙酰胺(DMAc)或邻苯二甲酸二辛酯(DOP),分别在150℃和220℃下,采用热致相分离法制备了聚偏氟乙烯(PVDF)平板膜,研究了在较低温度下或高温下制得膜的性能和结构。结果表明,加入质量分数10%的DMAc在150℃下制膜,比采用纯的DBP为稀释剂时膜的通量提高了28%,过多DMAc的加入反而会使膜的通量降低;加入质量分数10%的DOP在220℃下制膜,膜的通量则下降了62%。同时采用扫描电镜观察了膜的截面结构,解释了采用不同混合稀释剂时膜形成不同结构的原因。     

聚丙烯/稀释剂溶液的热致相分离动力学研究

原位观察了聚合物/稀释剂体系的分散相液滴粗化过程,应用傅里叶变换对图像进行了分析,结果表明:随着相分离结构的生长,傅里叶变换光斑半径变小,散射矢量qm总体向减小的方向移动。研究表明:实验体系的相分离后期存在聚结熟化机理向水力学流动机理的转变。     

混合稀释剂制备PVDF微孔膜的结构与性能研究

以邻苯二甲酸二甲酯(DMP)和N,N-二甲基乙酰胺(DMAc)作为混合稀释剂,采用复合热致相分离法制备聚偏氟乙烯(PVDF)微孔膜,并用扫描电镜、差示扫描量热分析仪、拉伸压缩材料试验机等测试仪器对微孔膜结构和性能进行了研究。结果表明:随着PVDF含量增加,体系的结晶度下降;随着混合稀释剂中DMP含量增加,膜强度先增大后减小,而水通量增加,截留率减小;冷却速率对孔隙率影响不大,但冷却速率减小,水通量增加,而截留率下降;DMAc与DMP质量比为1/2时,膜强度以及水通量均比单纯采用DMP做稀释剂时的好,前者的水通量达247 L/h.m2,比后者的增加了28%。     

稀释剂对TIPS法等规聚丙烯中空纤维微孔膜孔径及其连通性的影响

热致相分离（TIPS）法制备等规聚丙烯（iPP）中空纤维微孔膜,邻苯二甲酸二丁酯（DBP）与邻苯二甲酸二辛酯（DOP）的混合溶剂作为制膜稀释剂。干/湿氮气流量法测定了α（稀释剂中DBP的质量分数）和β（铸膜液中聚合物的质量分数）对膜样品的平均孔径及其分布的影响,并采用膜孔曲折因子定量表达膜孔连通性。发现全部膜样品均体现窄孔径分布特征。对于相同的β, α增加导致平均孔径及膜孔连通性下降。α=0.20时,β增加,膜的平均孔径先增加后降低,膜孔曲折因子稍下降; α=0.35或0.50时,β增加,膜的平均孔径降低,膜孔曲折因子下降。膜孔连通性体现了膜内部的拓扑结构,共溶剂组成和铸膜液固含量能够调节iPP中空纤维微孔膜的孔径及其连通性。     

我国复合热致相法PVDF中空膜实现产业化

北京格兰特膜分离设备有限公司在全球范围内率先实现了复合热致相分离法生产聚偏氟乙烯（PVDF）微滤／超滤中空纤维膜的产业化,目前已经形成了25万m2／a生产能力,今年年底还将扩能至100万m2／a。该产品不仅质量提高,而且价格比国外同类产品低一半左右。     

萃取和干燥对热致相分离制备聚丙烯微孔膜的影响

应用相对膜体积变化对萃取和干燥的影响进行表征,研究了萃取剂表面张力、沸点以及相互作用与微孔收缩之间的关系,实验结果表明随普萃取剂表面张力的增大、沸点的升高、相互作用的增强,相对膜体积呈下降趋势。这说明毛细管压力的大小、作用时间以及萃取剂对微孔壁的软化作用都会对微孔收缩产生重要影响。     

螺旋片导流式气液分离器的数值模拟与试验研究

The gas/liquid spiral separator, a key component in the compressed air system, was used to remove liquid and oil from gas stream by centrifugal and gravitational forces. To optimize the design of the separator, the relationship between the performance and structural parameters of separators is studied. Computational fluid dynamics （CFD） method is employed to simulate the flow fields and calculate the pressure drop and separation efficiency of air-liquid spiral separators with different structural parameters. The RSM （Reynolds stress model） turbulence model is used to analyze the highly swirling flow fields while the stochastic trajectory model is used to simulate the traces of liquid droplets in the flow field. A simplified calculation formula of pressure drop in spiral structures is obtained by modifying Darcy＇s equation and verified by experiment.     

Formation of microporous membrane of isotactic polypropylene in dibutyl phthalate‐soybean oil via thermally induced phase separation

Isotactic polypropylene (iPP) microporous membranes were prepared via the thermally induced phase separation (TIPS) process with the diluents being dibutyl phthalate (DBP) and soybean oil mixture. By changing the weight ratio of DBP to soybean oil systematically, it was determined experimentally that the cloud‐point curves were influenced to a great extent, while the crystallization curves showed much less dependence on the diluents composition. Scanning electron microscopy (SEM) showed that the resulting membrane morphologies changed significantly by varying the composition of the diluents, i.e., by changing the interaction parameter and other characteristics of diluents, the interwoven or celluar structure can be fabricated successfully at a fixed polymer concentration under the same cooling conditions. Different growth rates of iPP spherulite were obtained in the diluents with different composition. It is shown that the spherulites growth rates may be also attributed to the great variations of the final microporous morphology to a certain extent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

用拟二元方法研究iPP-DBP-DOP三元体系的热致相分离热力学

采用拟二元方法研究等规聚丙烯（iPP）‐邻苯二甲酸二丁酯（DBP）‐邻苯二甲酸二辛酯（DOP）三元聚合物溶液的热致相分离热力学,得出了拟二元相图的数学关联方法.采用光学显微镜法测定浊点温度, 采用差式扫描量热法（DSC）测定熔点、动态结晶温度.利用浊点测定数据回归聚合物-共溶剂的交互作用参数 χ的表达式,χ是共溶剂配比和温度的函数,以此为基础计算的拟二元相图与实验数据吻合较好.发现共溶剂中DBP份数增加,相分离类型由单纯固液分相形式转变为液液分相、固液分相依次发生形式,共溶剂配比能调控拟二元相图结构.研究表明,只需测定一个较低冷却速率下几种共溶剂配比的拟二元溶液的浊点温度、分别测定几个冷却速率下iPP–DOP二元溶液的动态结晶温度即可掌握该三元溶液热致相分离热力学的全部信息.其可用来指导制膜过程,并能准确预测形成的膜结构形貌.     

Preparation and characterization of several types of polyvinyl butyral hollow fiber membranes by thermally induced phase separation

Hollow fiber membranes were prepared by thermally induced phase separation from three types of polyvinyl butyral (PVB) and a blend of two of these polymers. Although the difference in the chemical composition of the PVB polymers used was not remarkable, their respective membrane performances were quite different. With a high phase separation temperature the pore size of the prepared membrane was large, because structure growth occurred for a long time. Water permeability tests of the wet membranes showed the results that corresponded to the pore sizes of the membranes. By contrast, the results for the dried membrane appeared to be related to the hydrophilicity of the PVB polymer and independent of pore size in the wet condition. Although the membrane with high wettability had low mechanical strength, the membrane from the polymer blend of two different PVB polymers showed adequate wettability and mechanical strength. This produced a hollow fiber membrane with favorable characteristics for application in water treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

热致相分离技术制备组织工程支架

用生物可降解材料制备细胞生长支架是组织工程的关键技术之一,而热致相分离技术是制备生物可降解三维多孔支架的重要方法.综述了凝胶浇铸、热致凝胶化、乳化/冷冻干燥、固液相分离和液液相分离等几种相分离技术的原理及应用,并预测了相分离技术的应用前景.     

热致相分离法平片式聚(乙烯-乙烯醇)微孔膜的制备和表征

以丙三醇为稀释剂,用热致相分离方法(TIPS)制备了无纺布支撑的平片式聚(乙烯-乙烯醇)(EVOH)微孔膜。实验研究了冷却速率及EVOH初始浓度对膜结构及性能的影响,测定了EVOH／丙三醇体系的相图．用扫描电子显微镜(SEM)及泡点法表征了微孔膜的微观结构及表面孔径,同时测试了膜的纯水通量。结果表明,随着冷却速率的加快,结晶曲线向低温移动。EVOH初始浓度决定了体系的相分离方式．由液-液相分离及固-液相分离机理形成的膜分别具有花边结构与球间缝隙结构;冷却速率影响膜的孔径大小和形态。随着冷却速率及EVOH初始浓度的降低,膜的孔径及纯水通量均逐渐增大。     

壁面粗糙度对气粒两相流动中颗粒行为影响的实验研究

The effect of wall roughness on particle behavior in two-phase flows in a horizontal backward-facing step is studied using a phase-Doppler particle anemometer. The results show that the wall roughness widens the particle velocity probability density distribution, enhances the redistribution of particle velocity into different directions,reduces the particle longitudinal mean velocity and increases the longitudinal and transverse fluctuation velocities and Reynolds shear stress. The effect of roughness on particle motion in the recirculation zone is weaker than that in the fully developed flow region. The effect of roughness for small particles is restricted only in the near-wall region, while that for large particle diffuses to the whole flow field.