共查询到20条相似文献,搜索用时 114 毫秒
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Robert Blank Karl-Heinz Muth Sabine Proske-Gerhards Eberhard Staude 《Colloids and surfaces. A, Physicochemical and engineering aspects》1998,140(1-3):3-11
Asymmetric ultrafiltration membranes were prepared from fully aromatic polyamides differing in the diamine monomers of the polymeric backbone and from polysulfone. Nanofiltration membranes were made from polysulfone and polyethersulfone. The polysulfone as well as the polyethersulfone were chemically modified to change the surface charges of the membranes that were made from these polymers. This means neutral, positively as well as negatively charged membranes could be employed for the measurements. The surface properties of the membranes as a function of pH were determined by measuring the streaming potential in a perpendicular and horizontal mode. Applying proteins the values of the streaming potential changed depending on the original charges of the membranes as well as on the pH of the solution. The values shifted to either higher or lower absolute values. Thus, characterization of unused and used membranes can be carried out by electrokinetic measurements. This was also demonstrated using a membrane fitted out with invertase. The zeta potential of nanofiltration membranes, however, was only evaluated from the results obtained with the horizontally run cell. 相似文献
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The effects of water vapor on the separation of CO2 and CH4 using cellulose acetate, polyethersulfone, polysulfone and sulfolene modified poly(vinylidene fluoride) membranes were determined. Response surfaces of flux on a dry basis and separation factor clearly show the effects of feed gas water vapor content and temperature on the permeation characteristics of the film. Strong trends of a plasticizing effect due to the concentration of water in the membranes were apparent. In general, in the commercial films, the flux went through a maximum with increasing feed water content while the separation factor decreased. These variables changed little in the sulfolene modified film. At 90°C, water permeation accounted for up to 35 percent of the total permeate. 相似文献
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Changes in the contact properties of the surface of polyethersulfone films modified at the cathode and the anode by dc discharge with varying the treatment time and discharge current have been studied. It has been shown that the treatment imparts hydrophilicity to the films, which persists for a long time. The chemical composition and structure of the surface of the modified films has been examined using X-ray photoelectron spectroscopy. 相似文献
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《Journal of membrane science》1997,129(1):125-133
Streaming potential measurement of ultrafiltration (UF) membranes have been realised a new design. This new design is more convenient to determine the streaming potential on a function of the pressure for all kinds of modules (planar, hollow fiber.h.). The effects of pH, ionic strength and size of pores have been studied. Isoelectric points of different materials (polyethersulfone, celloulse acetate, cellulose triacetate and polysulfone membranes) have been experimentally determined from ν variations with pH at a given ionic are, respectively, 3.1, 4.2, 3.4 and 0.5. The study of the charge organic membranes studied has been shown that adsorbing ions are those of water itself. Then the surface charge of the membrane is a dependent on the pH and at the isoelectric point, the charge density and the streaming potential vanished. The polyethersulfone membrane surface has been modified with TX100 adsorption and the modification observed with our design compared to contact angle and permeabilities measurements. The orientation angle of the surfactant at the membrane surface is obtained: θ=5°, and shows that a flat adsorption occurs. The impact of membranes cleaning procedures have been studied in term of permeability completed by streaming potential measurements. It appeared clearly that streaming potential is a useful tool for the control of cleaning procedures. 相似文献
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Water sorption and transport properties for a series of polysulfones are presented and interpreted in terms of the changes in the structure of the repeat unit compared to that of bisphenol A polysulfone. The differences between the sorption and diffusion of water and of permanent gases in these materials are also discussed. Water has the ability to interact with the polymer and with itself through hydrogen bonding in a way that permanent gases cannot. The equilibrium solubility of water in the polymer, unlike permanent gases, does not have a simple dependence on free volume but correlates more strongly with the frequency of hydrogen bonding sites on the polymer. Analysis of the sorption isotherms using the method of Zimm and Lundberg suggests that water molecules cluster in these polysulfones to various extents. For each polysulfone except polyethersulfone, the water diffusion coefficient decreases with increasing activity, which also suggests water clustering. For most of these materials, the water diffusion coefficient is larger than that of bisphenol A polysulfone and is directly related to the polymer free volume. Water permeability in these materials broadly correlates with the polymer free volume, but a favorable water-polymer interaction can be an overriding factor. © 1996 John Wiley & Sons, Inc. 相似文献
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F. Schu G. Clarotti J. Sledz A. Mas K.E. Geckeler W. Gpel A. Orsetti 《Macromolecular Symposia》1993,73(1):217-236
The deposition of films from an argon plasma containing a mixture of ethylene oxide or hydrogen and perfluorohexane was tried to obtain very hydrophobic, less hydrophobic and intermediate coatings. This paper studies more extensively the deposition of a thin coating from a perfluorohexane and hydrogen plasma on polysulfone and polyhydroxybutyrate membranes to optimize their surface properties without affecting their filtering properties. The plasma deposition of smooth and very hydrophobic fluorocarbon coatings seems to increase the bio- and hemocompatibility of poorly biocompatible membranes. The treated substrates were characterized by measuring the mass variations, surface profilometry and contact angle measurements, as well as scanning electron microscopy and electron spectroscopy for chemical analysis. 相似文献
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Yuying Yang Xiuli Shang Chao Kong Hongxiao Zhao Zhong’ai Hu 《Frontiers of Chemistry in China》2006,1(4):484-487
Polyaniline (PANI)/polysulfone (PSF) composite films are successfully prepared by phase separation and one-step in-situ polymerization.
It is found that the head-on face (in contact with solution) of the films is green while the back face is white. The chemical
component and the surface morphology of both surfaces of the films are characterized by FT-IR spectra and SEM, respectively.
The effect of the polymerization temperature, time and concentration of the reactants on the electrical properties of the
films are discussed in details. The thermo-oxidative degradation of the films is studied by thermogravimetric analysis (TGA).
The results indicate that the thermal stability of the PANI/PSF films is higher than that of the pure PSF film.
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Translated from Journal of Northwest Normal University (Natural Science), 2005, 39(11) (in Chinese) 相似文献
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One of the critical issues for membrane application in wastewater treatment is membrane fouling majorly caused by dissolved
organic matters. The aim of the present study was to lower membrane fouling by adsorption of polyelectrolytes. In the paper,
the feasibility of coating for diverse ultrafiltration membrane materials was investigated and their filtration performance
was compared to that of the unmodified ones. Different ultrafiltration flat-sheet membranes, polyvinylidene fluoride, polyethersulfone,
polysulfone and cellulose acetate were coated by branched poly(ethyleneimine) (PEI), poly(diallyldimethylammonium chloride)
(PDADMAC) and poly(allylamine chloride) (PAH) and filtrated with sludge supernatant. Short term experiments showed a substantial
drop of permeability: almost 40 % for PEI, 23 % for PDADMAC, and about 19 % for PAH coating. This deterioration resulted from
the additional resistance of the deposited layers. On the other hand, coating led to lower fouling rates during filtration.
In the stable state of filtration, coated membranes showed higher permeabilities compared to the uncoated ones. For the polyethersulfone
membrane, the average permeability enhancement was 11 %. For polysulfone and cellulose acetate membranes, the permeability
improved by 28 % and 15 % respectively. For polyvinylidene fluoride membranes only coating with PDADMAC enhanced the permeability,
by 13 %. PEI and PAH modified membranes featured lower permeabilities than the uncoated ones.
Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May
2008. 相似文献
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Comparison of redox initiated graft polymerisation and sulfonation for hydrophilisation of polyethersulfone nanofiltration membranes 总被引:1,自引:0,他引:1
B. Van der Bruggen 《European Polymer Journal》2009,45(7):1873-5980
Three polyethersulfone nanofiltration membranes, including two commercial membranes (NFPES10 and N30F) and one lab-made membrane (N71), were hydrophilised in view of an increased water flux and a reduction of membrane fouling.Non-modified as well as modified membranes were characterized using contact angle measurements, water fluxes and retention of sugars.At first, redox initiated graft polymerization was applied, and the influence of reaction time, initiator concentration and monomer concentration were investigated. It was observed that grafting always resulted in a significant reduction of the contact angle. The higher the reaction time, the lower was the contact angle, but the initiator and monomer concentration had no effect when above a threshold value. Grafting results in a decrease of the water flux, while the retention of raffinose increased.A comparison was made with the addition of sulfonated polyethersulfone to the polymer solution. By blending polyethersulfone and sulfonated polyethersulfon, a sufficiently high viscosity could be achieved. The influence of the blending ratio was investigated. The larger the fraction of sulfonated polyethersulfon, the more hydrophilic the membrane became. The addition of sulfonated polyethersulfon, however, has also an influence on the water flux and on the retention of sugars. An important conclusion is also that the membranes containing sulfonated polyethersulfone are significantly more hydrophilic than the ones that have been modified through the grafting technique. 相似文献
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Surface and interfacial segregation of polyethersulfone deuterated chain ends determined by neutron reflectivity 下载免费PDF全文
Katrina M. Knauer Joel Pollino Jonathan Schwartz Levi M. J. Moore Sarah E. Morgan 《Journal of Polymer Science.Polymer Physics》2017,55(3):293-301
The surface localization of polymer chain ends has been shown to be an effective method for surface composition control in amorphous polymer films. This work determines chain end distribution in thin polyethersulfone (PESU) films end‐capped with deuterated compounds of varying size and composition. Neutron reflectivity revealed the preferential localization of chain ends to the PESU‐air interface, independent of chain end identity. The length scale of the chain end concentration gradient was determined to differ from that predicted for flexible chain polymers. Atomic force microscopy and contact angle analysis demonstrated that chain end localization allows for improved control of nanoscale and macroscale surface properties of PESU films. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 293–301 相似文献
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Partial vapor pressures were measured for the volatiles of solutions of polysulfone or polyethersulfone in mixtures of N,N‐dimethylformamide (DMF, solvent) and water or acetone (precipitants) by means of headspace gas chromatography. The results demonstrate that the enrichment of water in the gas phase increases exponentially with rising polymer concentration, in contrast to that of acetone which remains constant. The reinforced expulsion of water resulting from the presence of polymers is theoretically conceivable and should be useful in the field of separation techniques. 相似文献
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用4种热致液晶聚合物分别与聚丙烯,聚对苯二甲酸丁二酯,聚碳酸酯,聚醚砜和聚砜搭配,在各聚合物对的“加工窗口“温度范围内熔融共混并挤塑得到6种共混物。藉流变仪,扫描电子显微镜,偏光显微镜,动态力学谱仪等重点研究了原位复合材料中微纤结构的形成,组分特性,熔体粘度,挤塑温度和浓度等因素对各向异性结构形成的贡献,以及液晶聚合物对聚合物结晶的诱导作用和两相间的相互作用。 相似文献
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The aim of this study was to investigate physical and mechanical properties of graphene oxide (GO)/polyethersulfone (PES) nanocomposite films. The films were produced by solution casting method. The mechanical properties of composite films were evaluated by tensile test. A significant enhancement in the mechanical properties of neat PES films was obtained incorporating a small amount of GO loading (0.05–1 wt.%). The highest tensile strength was observed at 1 wt.% of GO. Comparisons were made between experimental data and the Halpin–Tsai model predictions for the tensile strength and modulus of GO/PES composites. The effect of an orientation factor on model predictions was also acquired. The hydrophilicity of the nanocomposite was evaluated by assessing contact angle and enhanced wet ability of the films was obtained with increasing the amount of GO up to 1%. The morphology of the nanocomposites was investigated using scanning electron microscopy and transmission electron microscopy and the results revealed a good dispersion of GO in the PES matrix. The thermal behavior of the composite was also studied. Thermal stability of composites was increased by adding the GO. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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《Colloids and surfaces. B, Biointerfaces》2010,78(2):270-278
Polyelectrolyte multilayer (PEM) films have been recently applied to surface modification of biomaterials. Cellular interactions with PEM films consisted of weak polyelectrolytes are greatly affected by the conditions of polyelectrolyte deposition, such as pH of polyelectrolyte solution. Previous studies indicated that the adhesion of several types of mammalian cells to PAH/PAA multilayer films was hindered by low pH and high layer numbers. The objective of this study is to evaluate whether the hemocompatibility of polysulfone can be modulated by deposition of poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA) multilayer films. PAH/PAA multilayer films with different layer numbers were assembled onto polysulfone at either pH 2.0 or pH 6.5. The number of platelet adhesion and the morphology of adherent platelets were determined to evaluate hemocompatibility of modified substrates. Compared to non-treat polysulfone, the PEM films developed at pH 2.0 decreased platelet adhesion, while those built at pH 6.5 enhanced platelet deposition. Platelet adhesion was found positively correlated to polyclonal antibodies binding to surface-bound fibrinogen. The extent of platelet spreading was increased with layer numbers of PEM films, suggesting that the adherent platelets on thick PEM films were prone to activation. In conclusion, PAH/PAA films with few layers developed at pH 2.0 possessed better hemocompatibility compared to other substrates. 相似文献
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Sara Pedram Hamid R. Mortaheb Houssam Fakhouri Farzaneh Arefi-Khonsari 《Plasma Chemistry and Plasma Processing》2017,37(1):223-241
Thin films of fluorocarbon were deposited on polyethersulfone membranes via argon plasma sputtering of a poly(tetrafluoroethylene) (PTFE) target in an RF magnetron plasma reactor. The obtained deposited ultrathin coatings had nanoscale roughnesses and high degrees of fluorination. The intensity of fluorine atom in plasma environment during fluorocarbon deposition was investigated. Depending on the deposition conditions comprising working gas pressure, applied RF power, and distance between the target and the substrate, polymeric films with different chemical compositions and/or morphologies were obtained. The morphologies of the films were analyzed by means of SEM, XPS, and AFM. The results suggested that the sputtered film deposited at a higher pressure and longer target–substrate distance and moderate RF power had a surface composition and chemical structure closer to those of the PTFE film. The treated hydrophobic PES membranes with water contact angles as high as 115° were applied for the first time in an air gap membrane distillation setup for removal of benzene as a volatile organic compound from water. The results showed that the plasma-treated membranes have a comparable or superior performance to that of commercial PTFE used in membrane distillation with similar permeate flux and separation factor after 20 h long term performance. 相似文献
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Doris Pospiech Liane Häußler Dieter Jehnichen Wolfram Kollig Kathrin Eckstein Karina Grundke 《Macromolecular Symposia》2003,198(1):421-434
The goal of the investigation presented here is the development of extremely hydrophobic materials based on polysulfone that can be applied, for instance, as fouling-resistant membrane materials. The concept used is the addition of semifluorinated polymers to polysulfone in suitable blend compositions. The influence of molecular parameters like chain structure of the semifluorinated polymer (segmented block copolymers, random copolymers) and segment molecular weight on the state of phase separation in the bulk and its influence on the surface properties have been systematically examined. It could be shown that segmented block copolymers with semifluorinated polyester segments with intermediate segment molecular weight are more suitable in blends with polysulfone than random polysulfone copolymers having semifluorinated side chains with respect to form homogeneous thin films (coatings) with highly non-wetting properties. 相似文献