Studies on syntheses and permeabilities of special polymer membranes, 32. New preparation method of cellulose membranes

The preparation of cellulose membranes from mixtures of cellulose, nonprotonic polar organic solvents, paraformaldehyde, and basic catalyst was studied. When dimethyl sulfoxide was used as casting solvent, the resulting membrane was the densest. An increase of an additional amount of triethyl amine used as basic catalyst gave denser membranes.     

Studies on syntheses and permeabilities of special polymer membranes. 22. Ultrafiltration characteristics and membrane structure of cellulose nitrate membranes

The formation mechanism of anisotropic polymer membranes formed by a system of cellulose nitrate (CN)/n-propyl alcohol (n-PrOH)/N,N-dimethyl formamide (DMF) was investigated. The ultrafiltration characteristics and the membrane structure were influenced significantly by the casting solvents (ratio of n-PrOH to DMF) and the evaporation period during the membrane formation process. The finger-like structure in the sponge layer was observed in all systems except that of n-PrOH/DMF = 2/1 and increased with the evaporation period, after 2 min in the system of pure DMF and after 5 min in the system of n-PrOH/DMF = 1/3. The formation mechanism of the anisotropic CN membranes and the ultrafiltration characteristics were discussed in detail.     

Preparation and Characterization of Hybrid Chitosan/Acrylic Resin Emulsions and Their Films

Summary: Solutions containing chitosan of different molecular weights and several acidic monomers were prepared under various aging conditions. Hybrid chitosan/acrylic resin emulsions were prepared from these solutions by emulsion polymerization. The viscosities of the hybrid chitosan/acrylic resin emulsions were influenced significantly by the molecular weight of chitosan, the acidic monomer used, and the aging conditions. DSC and FT‐IR spectroscopy of the hybrid chitosan/acrylic resin films indicated that chitosan was well distributed in the films. The water absorption and formaldehyde adsorption abilities of the acrylic resin films prepared with chitosan were higher than the corresponding films prepared without chitosan, and they increased with increasing molecular weight of the chitosan. The morphology of these films, studied by TEM, revealed that the distribution of chitosan in the hybrid chitosan/acrylic resin emulsion was dependent on the molecular weight of chitosan, the acidic monomer used, and the aging conditions.

Chitosan salts with acrylic acid (R = ? CH?CH₂), methacrylic acid (R = ? C(CH₃)?CH₂) and itaconic acid (R = ? CH₂(COOH)C?CH₂).     

Studies of syntheses and permeabilities of special polymer membranes

Summary A new method of enzyme immobilization by a polyion complex was proposed. An enzyme immobilizing membrane was prepared by ultrafiltrating a mixture consisted of quarternized chitosan, sodium polyacrylate and invertase in an aqueous NaBr solution. The permeation and hydrolysis characteristics of aqueous sucrose solution through the invertase immobilizing membrane was studied under some conditions. A hydrolysis rate of sucrose by the invertase immobilizing membrane corresponded to the Michael is-Menten type reaction.     

Studies on syntheses and permeabilities of special polymer membranes

Summary An ion exchange membrane containing carboxyl groups, insoluble in acidic and alkaline aqueous solutions, was prepared from poly(isobutylene-alternating co-maleic anhydride) and poly(vinyl alcohol). Using the membrane in a diaphragm cell, one side being adjusted to be acidic and the other alkaline, it was possible to transport actively and selectively alkali metal ions through the membrane from the alkaline side to the acidic side.     

Studies on syntheses and permeabilities of special polymer membranes: 33. Permeation behaviour of aqueous alcohol solution through cellulose membranes

The permeabilities of various aqueous alcohol solutions through cellulose membranes were investigated by changing the preparation conditions of membranes, the feed concentration, and the feed solute, etc. The permeation rates for aqueous solutions of alcohols, glycols, glycerol, trihydroxyl benzene were greater than for pure water. This permeation phenomenon could be explained by some permeation models considering water cluster, activation of water molecules (second bound water-like) attached weakly to the bound water in cellulose membrane, and the surface of cellulose membrane, and plasticization of cellulose molecules.     

Permselectivities of poly(vinyl chloride) membrane for binary alcohol mixtures in pervaporation

Summary Permeation and separation characteristics of binary alcohol mixtures for relatively hydrophobic polymer, poly(vinyl chloride) (PVC), membrane were investigated on pervaporation. In single component measurements, it was found that small-sized alcohol had high solubility and high normalized permeation rate for the PVC membrane. In binary mixture measurements, small-sized alcohol was preferentially incorporated into the PVC membrane in all alcohol mixtures and was predominantly permeated through the membrane. It was found that the solubitity and diffusivity of small-sized alcohol was higher than those of other alcohols in all systems.     

Preparation and characteristics of a waterborne preventive stain coating material with organic-inorganic composites

With the goal of developing a waterborne coating material that prevents staining, organic-inorganic composites prepared from colloidal silica and two types of acrylic resin emulsions were investigated as exterior coatings. conventional acrylic resin emulsion and organic silane hybridized acrylic resin emulsion prepared by emulsion polymerization were mixed with colloidal silica to form organic-inorganic comiposite films. The addition of colloidal silica to emulsions yielded films with higher hydrophilicities, as indicated by lower water contact angles for these films in comparison to films without colloidal silica. The water contact angles of organic silane hybridized acrylic resin emulsion/colloidal silica films were lower than those of acrylic resin emulsion/colloidal silica films. Composite films containing colloidal silica particles smaller than 100 nm in diameter showed high hydrophilicities. Observations of the dispersed state of colloidal silicaparticles in organic-inorganic composite films by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that colloidal silica particles were densely aggregated on the film surface. Outdoor exposure tests of the coating materials prepared from organic silane hybridized acrylic resin and colloidal silica particles with diameters of 7.5 nm showed excellent stain resistance.     

Permeation and separation characteristics of alcohol–water mixtures through poly(dimethyl siloxane) membrane by pervaporation and evapomeation

Permeation and separation characteristics for aqueous alcoholic solutions such as methanol/water, ethanol/water and 1-propanol/water were studied using a poly(dimethyl siloxane) membrane by pervaporation and evapomeation. Poly(dimethyl siloxane) membrane preferentially permeated alcohol from aqueous alcoholic solutions in both methods. The concentration of alcohol in the permeate by evapomeation was higher than that by pervaporation. However, the permeation rate for the former method was smaller than that for the latter method. In evapomeation with a temperature difference between the feed solution and the membrane surroundings, when the temperature of the membrane surroundings was kept constant and the temperature of the feed solution was raised, both the permeation rate and the permselectivity for ethanol increased with increasing temperature of the feed solution. On the other hand, as the temperature of the feed solution was kept constant and the temperature of the membrane surroundings was changed, the permeation rate decreased, but the permselectivity for ethanol increased remarkably with dropping temperature in the membrane surrounding. Under permeation conditions of a feed solution of 40°C and a membrane surrounding temperature of ?30°C in evapomeation, an aqueous solution of 10 wt % ethanol in the feed was concentrated to about 90 wt % in the permeate. The permselectivity for alcohol was in the order of methanol <ethanol <1-propanol. The above permeation and separation characteristics are discussed from the viewpoint of the physicochemical properties of the poly(dimethyl siloxane) membrane and the permeating molecules.     

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.