Studies on syntheses and permeabilities of special polymer membranes

Summary An active transport of alkali metal ion through cation exchange membranes was studied under various conditions. This active transport was facilitated by using a greater anion species on an acidic side in a diaphragm cell, in which one side of the solution was adjusted to be acidic and the other side alkaline across the membrane. An active transport fraction of alkali metal ion was in order poly(styrenesulfonate)>benzenesulfonate>Cl^– >I^–>Br^– of anion species on the acidic side. A rate, fraction and period of the active transport of metal ion were significantly influenced by an electric potential gradient in the membrane.     

Studies on syntheses and permeabilities of special polymer membranes.: 15. Permeation characteristics of nylon-12 cellulose acetate blends

The permeation characteristics of nylon-12-cellulose acetate polymer blend membranes in the separation of polymers, poly(vinyl alcohols), from their aqueous solutions were investigated under various conditions. The permeation characteristics were influenced markedly by the ratio of nylon-12-cellulose acetate, the feed concentration, the operating pressure and temperature. It was found that the changes of polymer ratio and the concentration of blended polymer were related to the change of microporous structure of the resulting membranes. When the cellulose acetate content was higher a significant compaction of the membrane occurred under pressure. It was found that there was a concentration polarization of poly(vinyl alcohol) molecules on the membrane surface, whose thickness increased with increase in molecular weight of poly(vinyl alcohol) and in feed concentration. The bursting strength of the polymer blend membranes swollen with water increased considerably as the cellulose acetate content in the blended polymer increased.     

Studies on syntheses and permeabilities of special polymer membranes. IV. Permeation characteristics of improved cellulose nitrate membranes

For the purpose of the application of cellulose nitrate membranes for artificial kidneys, the permeation characteristics and the bursting strength of three types of membranes, which were prepared from a system of cellulose nitrate/methyl alcohol/1,4-dioxane/barium perchlorate (CN-1), from a system of cellulose nitrate/methyl alcohol/formamide (CN-2), and a poly(ethylene terephthalate) cloth coated with the casting solution of CN-2 (CN-3), were investigated under various conditions. It was found that permeabilities of these membranes were influenced significantly by the preparation methods of the membranes and the permeation conditions, and they depended upon the structure of the resulting membranes and the interaction between the polymer in the membrane and the feed. In blood filtrations, the permeation rates of our three types of membranes had about four-fold values than a cuprophane membrane, and moreover no protein was found in the blood filtrate. The bursting strength of the membranes swollen with water was in the order CN-3 > cuprophane > CN-2 > CN-1, and this ratio was calculated to be about 5.9:1.0:0.5:0.3     

Preparation of polydimethylsiloxane/polystyrene interpenetrating polymer network membranes and permeation of aqueous ethanol solutions through the membranes by pervaporation

Polydimethylsiloxane (PDMS)/polystyrene (PSt) interpenetrating polymer network (IPN) membranes were prepared by the bulk copolymerization of styrene and divinylbenzene in the PDMS networks. The interpenetration of PDMS and PSt resulted in the improvement of mechanical properties of PDMS. Transmission electron microscope (TEM) observation demonstrated that the PDMS/PSt IPN membranes have microphase-separated structures consisting of a continuous PDMS phase and a discontinuous PSt phase. When an aqueous ethanol solution was permeated through the PDMS/PSt IPN membranes by pervaporation, the PDMS/PSt IPN membranes exhibited ethanol permselectivity, regardless of the PDMS content. The effects of their microphase-separated structures on the permeability and selectivity for aqueous ethanol solutions are discussed experimentally and theoretically. © 1996 John Wiley & Sons, Inc.     

Separation of aqueous organic liquid solutions through polymer membranes

Characteristics of permeation and separation for aqueous dimethyl sulfoxide, acetic acid and ethanol solutions through some polymer membranes such as chitosan, poly(vinyl chloride) and poly(dimethyl siloxane) membrane were studied by evapomeation. In temperature difference controlling evapomeation (TDEV), when the temperature of the feed solution was kept constant and the temperature of the membrane surroundings was changed, permselectivity for water increased in the chitosan and poly(vinyl chloride) membranes; in the poly(dimethyl siloxane) membrane the perm-selectivity for ethanol increased while decreasing the temperature of the membrane surroundings. Permeation and separation mechanisms for aqueous organic liquid solutions through the above polymer membranes by the TDEV method are discussed.     

Hydrogen production by hybrid process combined with assistance of solar and electric energies

To increase the efficiency for hydrogen production by solar decomposition of water in the photoelectrochemical local cell, it was advantageous to decompose an acidic aqueous electrolyte containing Fe³⁺ ions. In the photo-cell having an n-type semiconductor anode illuminated with solar light, the electrolyte decomposed to oxygen and Fe²⁺ ions with a quantum efficiency of ca 38% for light below 400 nm. The electrolyte containing the Fe²⁺ ions produced was electrolysed in the cell having a packed bed carbon anode and a platinum cathode deposited on a cation exchange membrane, producing hydrogen and Fe³⁺ ions with less than 1.0 V at 50 mA cm^?2 and was then fed back to the photo-cell.     

Studies on syntheses and permeabilities of special polymer membranes. 27. Concentration of poly(styrene sulphonic acid) in various aqueous solutions using poly(vinylidene fluoride) membranes

The permeation characteristics of poly(vinylidene fluoride) membranes in the separation and concentration of poly(styrene sulphonic acid), from various aqueous solutions were investigated under various conditions. The rejection of the polymer from its aqueous solution was high, because electrostatic repulsions between the charges along polymer chains cause chain extension. When a salt, such as sodium chloride, and sulphuric acid were added to the aqueous solution and the pH was changed, the configuration of the poly(styrene sulphonic acid) molecules changed significantly with the added amounts of salt. The permeation characteristics were influenced markedly by the conformational changes of polymer molecules and the viscosities of permeating liquids. The rejections were dependent on the conformational changes: the permeation rates were mainly governed by the viscosities. Poly(vinylidene fluoride) membranes had much superior resistance to acid, i.e. even when immersed in concentrated sulphuric acid for 7 days, the permeation characteristics did not change at all. The membranes were also effective for the concentration of poly(styrene sulphonic acid) and the removal of sulphuric acid from aqueous mixtures since the concentration of these solutes were optimum.     

Studies on syntheses and permeabilities of special polymer membranes: 24. Permeation characteristics of poly(vinylidene fluoride) membranes

The permeation characteristics of poly(vinylidene fluoride) membranes were investigated by changing the preparation conditions of the membranes, the composition of the casting solution, membrane thickness, time of heat treatment and temperature, etc.; and by changing the permeation conditions, operating temperature, the feed concentration, and the feed solute, etc. Aqueous solutions of poly(vinyl alcohol) and poly(ethylene glycol) were used as feed. The permeation characteristics were influenced significantly by the change of the above conditions and were dependent on the structure of resulting membrane, the viscosity of feed, the form of polymer molecules in aqueous solution, and the concentration polarization of polymer solute molecules onto the membrane surface. The permeation through very swollen membranes (ca. 85% in water content) followed the viscous flow.     

Properties of organic–inorganic composite materials prepared from acrylic resin emulsions and colloidal silicas

To design an organic–inorganic composite material with colloidal silica as the inorganic component, an acrylic resin emulsion and an organic silane hybridized acrylic resin emulsion were prepared by emulsion polymerization. The organic–inorganic composite films were prepared by blending the emulsion and the colloidal silica. The contact angles for water, gloss at 60°, and the transparencies of those films were measured. The dispersion state of colloidal silica in films was observed with a scanning electron microscope (SEM) and a transmission electron microscope (TEM). From these results, the contact angle for water of the organic–inorganic composite film obtained from the silane hybridized acrylic resin emulsion was lower than that of the organic–inorganic composite film obtained from an acrylic resin emulsion. The contact angles for water in organic–inorganic composite films with colloidal silicas were lower than those of the films without the colloidal silicas. The films prepared from silane hybridized acrylic resin emulsion composites with colloidal silicas of less than 100 nm were more hydrophilic. SEM and TEM observations demonstrated that some aggregations of the small colloidal particle silica were densely dispersed on the film surface. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2051–2056, 2006     

Studies on syntheses and permeabilities of special polymer membranes. 37. Permeabilities of poly(γ-methyl L-glutamate) membranes

The permeation characteristics of poly(γ-methyl L-glutamate) (PMLG) membranes in the separation of polymers, poly(ethylene glycol) and poly(vinyl alcohol), from their aqueous solutions were influenced by the compaction of membrane swollen with water under pressure. The rate of pure water permeability up to an operating temperature of 70°C was governed by a change in the secondary-structure of PMLG. In addition, the permeabilities of alcohols through PMLG membrane were discussed.