海藻酸钠与PVA共混膜用于渗透汽化分离乙醇┐水混合物

制备了天然高分子海藻酸钠与ＰＶＡ的不同比例共混膜，并用于渗透汽化法分离乙醇－水混合物。结果表明，与均质ＰＶＡ膜相比，透过系数及分离系数均大幅度提高，尤其是当乙醇浓度低于８０％时，共混膜依然保持较高分离系数，在共混膜中，ＰＶＡ可起到增强力学强度，易于交联的作用。     

海藻酸钠与PVA共混膜用于渗透汽化分离乙醇—水混合物

制备了天然高分子海藻酸钠与ＰＶＡ的不同比例共混膜，并用于渗透气化法分离乙醇－水混合物。结果表明，与均质ＰＶＡ膜相比，透过系数及分离系数均大幅度提高，尤其是当乙醇浓度低于８０％时，共混膜依然保持较高分离系数，在共混膜中，ＰＶＡ可起到增强力学强度，易于交联的作用。     

壳聚糖-醋酸纤维素共混膜的制备及其渗透汽化性能

研究了壳聚糖（ＣＳ）与醋酸纤维素（ＣＡ）渗透汽化共混膜的制膜条件，测定了该膜对乙醇－水混合液的渗透汽化性能及平衡溶解吸附性能实验表明，壳聚糖－醋酸纤维素共混膜对乙醇质量分数为５０％～９５％的乙醇－水溶液具有良好的渗透汽化分离性能     

壳聚糖—醋酸纤维互共混膜的制备及其渗透汽化性能

研究了壳聚糖（ＣＳ）与醋酸纤维素（ＣＡ）渗秀汽化共混膜的制膜条件，测定了该膜对乙醇－水混合液的渗透汽化性能及平衡溶解吸附性能、实验表明，壳聚糖－醋酸纤维素共混膜对乙醇质量分数为５０－９５％的乙醇－水溶液具有良好的渗透汽化分离性能。     

聚偏氟乙烯/聚丙烯腈共混超滤膜的研究

讨论了聚偏氟乙烯／聚丙烯腈共混体系的相容性,对ＰＶＤＦ／ＰＡＮ共混体系的相容性进行了理论分析和相容性预测,并通过实验对相容性进行了评价。结果表明,ＰＶＤＦ／ＰＡＮ属部分共混体系。利用该体系可制得性能优良的ＰＶＤＦ／ＰＡＮ共混超滤膜,讨论了铸膜液的组成、制膜条件对膜性能的影响。并对膜性能和膜结构进行了测试。得到了较好的结果。     

渗透汽化复合膜的支撑层对分离性能的影响

研究了多种聚合物膜作为复合膜的多孔支撑层时的性能及其复合膜分离乙醇水给 物时的渗透汽化性能。结果表明,ＣＡ、ＰＡＮ－ＳＳ和ＰＳＡ分别为多孔支撑层的膜材料时,ＰＶＡ复俣的渗透汽化性能优良,尤其是ＰＶＡ／ＣＡ复合膜表现出特别优异的渗秀汽化分离性能。用国产涤纶布增强、聚合物浓度较高的铸膜液制备成厚度适宜的膜为支撑层,可获得理想分离性能的渗透汽化复合物。     

丙烯酸-丙烯酰胺共聚物渗透汽化分离性能研究

将丙烯酸 (AA) -丙烯酰胺 (AM)共聚物与聚乙烯醇 (PVA)共混制得优先透水的渗透汽化膜用于分离 4 0 %～ 95%的乙醇水溶液 ,研究了膜的热处理温度、分离温度、共聚单体摩尔比、制膜液 p H值等因素对膜分离性能的影响。当用 AA∶ AM=1∶ 1(mol)的共聚物与 PVA等质量共混 ,制膜液 p H=7,制得的膜经 16 0℃热处理后用于分离 95%的乙醇水溶液 ,其分离系数和透过速率分别为 PVA膜的 1.3倍和 8倍     

丙烯酸—丙类酰胺共聚物渗透汽化分离性能研究

将丙烯酸（AA）-丙烯酰胺（AM）共聚物与聚乙烯醇（PVA）共混制得优先透水的渗透汽化膜用于分离40%～95%的乙醇水溶液,研究了膜的热处理温度、分离温度、共聚单体摩尔比,制膜液pH值等因素对膜分离性能的影响,当用AA:AM=1：1(mol）的共聚物与PVA等质量共混,制膜液pH=7,制得的膜经160℃热处理后用于分离95%的乙醇水溶液,其分离系数和透过速率分别为PVA膜的1.3倍和8倍。     

壳聚糖渗秀汽化复合膜的研究

用聚丙烯腈（ＰＡＮ）超滤膜为底膜制成的壳聚糖（ＣＳ）复合膜，对乙醇／水溶液２的渗秀汽化分离性能具有较好的稳定性，复合膜用于运行低浓度的乙醇溶液后，再运行质量为９５％的乙醇溶液，膜的性能变化不大，稳定性优于均质膜，研究了用于多种试剂来代替硫酸交联剂处理膜，表明有些可有效地提高膜的涌透选择性，特别是用聚苯乙烯磺酸钾（ＰＳＳＫ）处理，膜的渗透通量达３１０－３３５ｇ／（ｍ＾２．ｈ），ｘｘ ｄｙｃ ｓｇｃｔ     

亲水性渗透蒸发脱盐膜的研究

将聚乙二醇（ＰＥＧ）分别与明胶（ＧＬＴ）、聚丙烯酰胺（ＰＡＭ）及聚乙烯醇（ＰＶＡ）等成膜高分子共溶于水中,制备亲水性高分子共混膜．对膜的微相结构和渗透蒸发脱盐性能进行了研究．结果表明,ＰＶＡ为理想的成膜聚合物．乙酸钠的引入改变了ＰＶＡ－ＰＥＧ体系的高分子网络结构和膜形态结构,提高了膜的通量．在５５℃时,其水通量为１４ｋｇ／（ｍ２·ｈ）,并具有极高的一次分离度．     

磺化聚芳醚酮砜/PVA复合质子交换膜的制备与性能

为了进一步提高质子交换膜在中高温时的质子导电率,文中以高磺化度的磺化聚芳醚酮砜(SPAEKS)和聚乙烯醇(PVA)为原料,通过溶液共混法制备了PVA不同含量的磺化聚芳醚酮砜/PVA复合膜。通过对复合膜的性能测试发现,PVA的引入提高了膜的热稳定性、吸水率和保水能力。而且SPAEKS/PVA复合膜的质子传导率高于SPAEKS膜,在80℃时,复合膜的质子传导率都在0.07 S/cm以上,能够满足中高温质子交换膜燃料电池的使用要求。     

聚丙烯接枝聚丙烯酸微滤膜的pH响应性

研究了聚丙烯接枝聚丙烯酸微滤膜的pH响应性及其在牛血清蛋白溶液过滤中的抗污染性。聚丙烯酸(PAA)接枝链可提高膜亲水性,但会造成膜孔堵塞:在低接枝率(<17%)下,PAA大幅度提高膜亲水性,膜通量和pH响应性随接枝率的增加逐渐增大;接枝率过大(>17%)时,PAA对膜孔的堵塞作用占主导,膜通量和pH响应性逐渐下降。与未接枝膜相比,在碱性条件下接枝膜对牛血清蛋白(BSA)分子具有一定的抗污染性能,而酸性条件下则加剧BSA对膜的污染,但改性后接枝膜的通量大幅度增长,使这种膜在BSA类蛋白质的微滤领域仍有较好的应用前景。     

氯化锂对聚乙烯醇／聚醚砜膜透湿性能的影响

把LiCl当作添加剂加入到聚乙烯醇(PVA)铸膜液中,以聚醚砜膜(PES)作为支撑层,制备PVA/PES复合膜.测试了复合膜的透湿性能.结果表明:由X射线衍射图得LiCl的加入降低了PVA膜的结晶度.PVA/PES复合膜与水的接触角随着LiCl含量的增加而逐渐减少,即随着LiCl含量的增加,复合膜的亲水性增强,这是由于LiCl具有强吸湿性.在保持铸膜液中PVA含量为8%,交联剂(苹果酸)、催化剂(乙酸)浓度不变的情况下,改变LiCl的含量,膜的水蒸气总传质系数、渗透速率和湿交换效率随着LiCl含量的增加呈上升趋势,数据趋势与X射线衍射图、接触角等现象相符合.添加LiCl所制的复合膜不仅不能透过CO2,而且还具有良好的水蒸气渗透性能.     

Polyetherurethaneurea reinforced poly(vinyl alcohol) dialysis membranes: studies on permeability and mechanical strength

Poly(vinyl alcohol) is a hydrogel which is extensively studied for a variety of biomedical applications. Membranes developed from crosslinked poly(vinyl alcohol) (PVA) is having excellent permeability to solutes. However its wet breaking strength is low. Polyetherurethaneurea (PEUU), having an excellent mechanical strength is blended with PVA as a reinforcement, and membranes developed are studied for its permeability and mechanical strength. The optimum membrane selected, is having permeability and wet breaking strength almost equal to the commercially available cellulose acetate membrane.     

聚四氟乙烯微孔膜及其无机粒子共混膜的结构及性能

以聚乙烯醇(PVA)为成膜载体,由聚四氟乙烯(PTFE)分散乳液制得PTFE微孔膜,通过对不同烧结温度的研究得出PTFE烧结模型,在烧结初期有利于PTFE形成微孔结构.在成膜体系中引入纳米无机粒子,得到PTFE/无机粒子共混平板膜.研究了无机粒子对共混膜结构及性能的影响,结果表明PTFE与碳酸钙(CaCO_3)粒子的粘结性差,在烧结成型过程中PTFE基质相与CaCO_3产生界面相分离形成微孔,形成的界面微孔不同于PTFE双向拉伸产生的纤维-结点状裂隙孔结构.共混膜经适当拉伸后孔隙率显著提高.     

Plasma-treated polyethersulfone coated with crosslinked poly(vinyl alcohol): composite membranes for pervaporation dehydration of ethanol

Composite membranes with crosslinked poly(vinyl alcohol) matrix as selective layer coated on a polyethersulfone supporting porous layer were prepared aiming at separating ethanol/water mixtures by pervaporation. A polyethersulfone asymmetric microporous membrane was synthesized by the wet phase inversion process. The support membrane was then exposed to air plasma to activate the surface. The selective dense layer was obtained by coating of PVA and a crosslinking agent over the polyethersulfone substrate, followed by thermal treatment. The morphology was examined by scanning electron microscopy (SEM) for both, support membrane and the coated polymeric layers. Surface physicochemical properties were evaluated through measuring the contact angle (θ) and the estimation of surface free energy (γ_S) and adhesion work. The surface chemical composition of support membrane and coated hydrophilic layers were characterized by infrared spectra with horizontal attenuated total reflectance (FT-IR/HATR). The swelling degree of PVA dense membranes, and the pervaporation performance of the crosslinked PVA/PES composite membranes, manufactured with several coating steps, were evaluated with water/ethanol (20/80 wt%) mixtures at temperatures in the range of 30–60 C. Results of the effective pervaporation dehydration of ethanol are discussed in terms of membrane morphology and the solution-diffusion transport mechanism.     

Ion-exchange membranes made of semi-interpenetrating polymer networks,used for pervaporation-assisted esterification and ion transport

Ionic membranes were prepared by blending poly(vinyl alcohol) (PVA) with an ionic polymer. Semi-interpenetrating polymer networks (sIPN) in which the crosslinked PVA chains trap the ionic polymer were obtained by using a heat treatment at 180 °C or dibromoethane vapor at 140 °C, respectively, for poly (styrene sulfonic acid) (PSSH), poly (sodium styrene sulfonate) (PSSNa), poly (acrylic acid) (PAA) or poly (dimethyl dimethylene piperidinum chloride) (PDMeDMPCl) as the ionic polymer. The stability of the sIPN membranes in some liquid media was studied to select the appropriate membranes for the envisaged applications. The thermally crosslinked PVA/PSSH membranes showed an effective catalytic effect on the esterification reaction between n-propanol and propanoic acid. An active composite membrane made of a layer of PVA/PSSH deposited on a dense PVA layer of an industrial dehydration membrane exhibited both high catalytic activity and high selectivity to water in the pervaporation-assisted esterification. The values of the counter-ion transport number indicated that some crosslinked ionic membranes have good ion permselectivity.     

Removal of water from aroma aqueous mixtures using pervaporation processes

In the field of food technology the main applications of pervaporation through hydrophilic membranes are the removal or extraction of water from aroma azeotropic aqueous mixtures. In this study, experiments for removal of water containing aroma compounds of ethanol, propanol, butanol, hexanol, ethyl acetate and acetic acid were performed through a composite, plate and frame type hydrophilic PVA (poly vinyl alcohol) membrane in a 0.5 m² plane module at constant feed temperature and permeate Vacuum pressure. The analysis is presented in terms of variations in permeation flux and separation factor. The results show the decrease in separation factor as well as permeation flux with the increase of alcohol in feed. Hexanol does not permeate through PVA membrane. Activity coefficient of water is higher than that of organic. Pervaporation selectivity differ from Liquid-vapor thermodynamic equilibrium.     

聚四氟乙烯膜的制备及性能

以聚乙烯醇(PVA)为成膜载体,由聚四氟乙烯(PTFE)分散乳液制得PTFE疏水膜,分析和讨论了膜烧结后的组成、动态力学性能的变化,用扫描电子显微镜(SEM)观察了膜表面形貌。结果表明:(1)制备的PTFE膜较PTFE在组成上无明显变化;(2)经定长和松弛状态烧结的PTFE膜,其DMA谱图的α转变较PTFE未发现较大变化;(3)经定长状态下烧结后所得PTFE膜中原纤网络结点之间构成了较为疏松的微孔结构,而在松弛状态下烧结所得膜的微孔结构较为致密。     

Effect of blending ratio on pervaporative separation of 1,4-dioxane/water mixtures through PVA-PEI membranes

Blend membranes were made by mixing aqueous solutions of hydrophilic polymers poly(vinyl alcohol) (PVA) and polyethyleneimine (PEI) in different ratios for investigating the separation of 1,4-dioxane/water azeotropic mixture by pervaporation (PV). Water forms azeotrope at 18 wt% concentration with 1,4-dioxane. The resulting membranes were characterized by FTIR to verify the interaction between the homopolymers, wide-angle X-ray diffraction (WAXD) to observe the effect of blending on crystallinity and thermal gravimetric analysis (TGA) to investigate the thermal stability. Sorption studies were carried out to evaluate the extent of interaction and degree of swelling of the blend membranes in pure liquids as well as binary mixtures. The effect of blend composition ratio on membrane parameters such as flux and selectivity was analyzed. An increase in PVA content in the blend caused a reduction in the flux and an increase in selectivity. Among the blends tested in the study, the 5:1 PVA/PEI blend membrane showed the highest separation factor of 44.01 and exhibited a flux of 0.733 kg/m² h 10 μm for azeotropic feed composition at ambient temperature (30 °C).