Porous Polypropylene Films Research Articles

DSC studies on bound water in polypropylene films plasma-grafted with 2-hydroxyethyl acrylate and acrylic acid or methacrylic acid

Water sorbed on porous polypropylene films, grafted to various extents by plasma-graft copolymerization of 2-hydroxyethyl acrylate with acrylic acid or methacrylic acid, was examined using differential scanning calorimetry. From the heat of crystallization or melting of water in the grafted membrane, the non-freezing water content ( W nf) was calculated using the relationship W c = W f + W fb + W nf, where W t is the total water content in the membrane and W f is the free water content with phase transition temperatures similar to those of ordinary water and W fb is freezing bound water. The W nf values became larger with increase in the number of hydrophilic groups (graft ratio) in the membrane. The separation factor of water-ethanol was correlated with W nf value. A simplified static heterogeneous model is suggested to explain the dynamic process of membrane separation for water and ethanol.

Plasma graft polymerization of N,N‐dimethylaminoethyl methacrylate and water–ethanol separation by pervaporation through the grafted membranes

AbstractN,N‐dimethylaminoethyl methacrylate was graft‐polymerized onto the porous polypropylene films of Celgard 2400 and 2500 which have been previously surface‐activated by glow discharge plasmas. The grafting was dependent on various factors both in the plasma pretreatment and the post‐polymerization with the monomer. The reaction was discussed from the aspects of the dependences of graft polymerization on discharge power, plasma pretreatment period, etc. When the grafting exceeded a critical amount depending on the size of pores on the substrate film, pervaporation of water‐ethanol separation functioned through these grafted membranes. The water permselectivity was improved by the ammonium ionization of the pendant N,N‐dimethylamino group using dimethyl sulfate or chloroacetic acid, although the increase of prevaporation performance was not so high as those previously obtained by the grafted poly(sodium acrylate) ‐type membranes. Pervaporation characteristics of these membranes were discussed from the ionized states of the permselective layers analyzed by IR and ESCA.

Application of a thermo-responsive membrane to the transdermal delivery of non-steroidal anti-inflammatory drugs and antipyretic drugs

Abstract A thermo-responsive membrane was incorporated into a transdermal therapeutic system (TTS) which responds to thermal stimuli associated with skin temperature changes. The thermo-responsive membrane was prepared by pouring monooxyethylene trimethylolpropane tristearate (MTTS) between two porous polypropylene films. The TTS with this thermoresponsive membrane as a rate controlling membrane released non-steroidal anti-inflammatory drugs (indomethacin, ketoprofen) and antipyretic drugs (acetoaminophen, ethenzamide) in response to temperature changes between 32 and 38°C in the in vitro experiments. It was then shown that the temperature-activated TTS was operative in vivo in a rabbit model .

Transportation of Zinc(II) Ion through a Supported Liquid Membrane

Abstract The transportation system of the zinc ion using a driving force supplied by the concentration gradient of the anion is studied in terms of permeation through a supported liquid membrane (SLM) containing a carrier. The SLM was prepared by impregnating a porous polypropylene film with a 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline (bathocuproine) solution with dibenzyl ether as the carrier. The zinc ion permeation behavior through the film is studied under various experimental conditions. The effects of the zinc ion concentration, anion, and carrier are determined, and a permeation velocity equation for the zinc ion through the membrane is proposed. The effects of types of carrier as well as of anions are also investigated.

Effects of hydroxyl group on water-ethanol separation by pervaporation using plasma grafted membranes.

2-Hydroxyethyl acrylate and 2-hydroxyethyl methacrylate were graft-polymerized onto plasma-pretreated porous polypropylene films, and their water-ethanol separation characteristics were investigated by pervaporation method. These composite membranes were hydrophilic, and water-permseparation was achieved. The results were compared to those obtained with the membranes grafted with 2-methoxy-ethyl acrylate and 2-methoxyethyl methacrylate for elucidating the effects of hydroxyl group on water-permselectivity. When the performance was compared by the relationship of separation factor and flux, the better pervaporation characteristics were observed generally in the hydroxyl group containing membranes. The properties were attributed to the higher adsorption of water through hydroxyl group in the grafted membranes.

Water-ethanol separation by pervaporation through plasma-graft-polymerized membranes of 2-hydroxyethyl methacrylate with acrylic acid or methacrylic acid

Membranes which selectively permeate water from water-ethanol mixtures were prepared by plasma-graft copolymerization of 2-hydroxyethyl methacrylate with acrylic acid or methacrylic acid in various mixing ratios on to porous polypropylene films that had previously been surfaceactivated by glow discharge plasma. Graft polymerization depended on the monomer composition, the mixing ratio, and the polymerization conditions, such as reaction period and temperature, as well as the plasma pre-treatment conditions. It was suggested by ESCA analysis that acrylic acid and methacrylic acid were copolymerized and that their extent of incorporation increased with the addition ratios. By control of the grafted amount of these polymers on the porous substrate films, water separation occurred by pervaporation. The minimum amount of graft polymers depended on the state of the membranes produced: i.e., polymer species, pore size of the substrate, etc. Flux was usually increased, and as a result permselectivity was decreased, by the copolymerization of acrylic acid and methacrylic acid to 2-hydroxyethyl methacrylate, and this tendency was greatly increased, as a rule, by ionization of these membranes in the sodium salt form.

Preparation of a single bipolar membrane by plasma-induced graft polymerization

A new type of single bipolar membrane was produced by plasma-induced graft polymerization. Acrylic acid was grafted on one side of a porous polypropylene film as a cation-selective region, and N-(2-methacryloyloxyethyl)- N,N,N-trimethylammonium chloride (QDM) on the other as an anion-selective region. The interface between the two regions consists of a porous structure retaining the original porous polypropylene framework. The rectification phenomenon, which is characteristic of the bipolar membrane, was observed for electric current and voltage between two membrane surfaces. As the membrane has the advantages of comparatively simple production, both in the laboratory and in industry, and the characteristic structure cited above, it should prove applicable to investigations on ion transport, as a biological model membrane in the field of biophysics, or to the production of chemical compounds as a novel membrane reactor in the field of biotechnology.

Enzyme immobilization in an asymmetric charged membrane

An entrapped enzyme asymmetric membrane was prepared by treatment of a porous polypropylene or polyethylene film by plasma-induced graft polymerization of acrylic acid on one side and N-(2-methacryloyloxyethyl)- N,N,N-trimethylammonium chloride on the other, followed by enzyme absorption through the pores of the film. Such a single membrane is called an immobilized-enzyme bipolar membrane. In this system, the reaction of urea by urease is studied. Using Donnan equilibrium and electroneutrality conditions for 1-2-valent ions, the permeation behavior of the system is interpreted. Although this model is unsuitable for use when a current is flowing, it provides insight into membrane design because it depends on structural parameters such as fixed charge density in the equations rather than on nonequilibrium thermodynamic theory. This type of membrane is applicable for use in reaction-separation systems as a compact membrane reactor.

Water–ethanol permseparation by pervaporation through the plasma graft copolymeric membranes of acrylic acid and acrylamide

Acrylic acid was copolymerized with acrylamide onto the porous polypropylene film which had been previously treated by glow discharge plasma, and the partially ionized membranes were prepared with treating in dilute sodium hydroxide aqueous solution. Using these membranes with different ratios of polyacrylate ion, water–ethanol permseparation was investigated. The membranes were water-permselective because of the hydrophilicity, and the permselectivity was increased by ionization generally for the feeds with ethanol concentration more than 50%. In the lower ethanol concentration range, the permselectivity was not so good because of the much higher permeation rate. When the permselectivity was evaluated by the products of separation factor (a) and Flux (Q), the copolymerized membranes with the acrylic acid mixing at 0.4 were superior to the ion-exchange membranes, although somewhat inferior to the ionized membranes of acrylic acid grafting which had been attempted previously. In the ionized membrane of the copolymer, the activation energy for permeation lied between 4.2 and 5.5 kcal/mol, and was much smaller than that of the neutral membranes before ionization; i.e., the decrease of flux was depressed even at the lower temperature.

Water‐ethanol separation by pervaporation through plasma graft polymerized membranes

AbstractWater‐ethanol permselective membranes were prepared through plasma graft polymerization of acrylic acid, methacrylic acid, and acrylamide onto porous polypropylene film. In these membranes, the functions of permseparation and mechanical properties are shared respectively to the graft polymer layer and the substrate film. Higher permselectivity of water is achieved with the ionization of the acrylic acid and the methacrylic acid‐grafted membranes. Permselectivity is dependent on the degree of grafting, and it is necessary to fill the pores of substrate film with graft polymers. Permseparation of water was investigated with respect to the feed ethanol concentration and also to the temperature dependence.

Mass transfer rate through solid supported liquid membranes: Influence of carrier dimerization and feed metal concentration on membrane permeability

The coupled transport of Cu 2+ and H + ions through solid supported liquid membranes consisting of a porous polypropylene film immobilizing a β-hydroxy-oxime (carrier) in toluene has been studied as function of both the hydrodynamic conditions and the chemical composition of the system. Data have been obtained using a wide range of metal concentrations, up to complete loading of the membrane carrier with Cu 2+ ions. The experimental results have been quantitatively explained by a previously derived permeability coefficient equation taking into account both the self-association and the progressive saturation by copper ions of the membrane carrier. The thickness of the aqueous diffusion films and the membrane diffusion coefficient of the Cu 2+—carrier complex have been evaluated.

FACILITATED TRANSPORT OF HNO3THROUGH A SUPPORTED LIQUID MEMBRANE CONTAINING A TERTIARY AMINE AS CARRIER

ABSTRACT The facilitated transport of HN03 through a supported liquid membrane consisting of a porous polypropylene film containing a solution of trllaurylamine 1n diethyl benzene as carrier was studied as a function of the stirring speed of the aqueous solutions and the membrane composition. A physico-chemical model which takes Into account diffusion through an aqueous boundary layer, a fast Interfaclal chemical reaction leading to the formation of a membrane soluble alkylammonium salt and diffusion through the membrane was proposed. In this way, equations were derived which describe how composition changes, occurring In the course of the permeation process, Influence the membrane permeability. The experimental data were quantitatively explained by the derived equations. The results indicate that the monomerlc form of the trllaurylammonium nitrate salt 1s the species which 1s mainly responsible for the acid transport through the membrane. The diffusion coefficient of the permeating species and the order ...

Transport of Eu3+through a Bis(2-ethylhexyl)-phosphoric Acid,n-Dodecane Solid Supported Liquid Membrane

Abstract The coupled transport of Eu3+ and H+ ions through a solid supported liquid membrane consisting of a porous polypropylene film immobilizing an HDEHP solution in n-dodecane has been studied as a function of the membrane area, stirring speed of the aqueous solutions, membrane composition, and acidity of the feed solution. The experimental results are in agreement with predictions derived from a theoretical permeability coefficient equation which assumes that membrane diffusion and aqueous film diffusion are the only rate-controlling factors.

多孔質膜の気体透過性と孔径分布 金属コーティングの効果

The effect of the reduction in specific surface area and pore size distribution on the gas permeability has been studied in porous polypropylene film with sputtered metal coating.The results are as follows; 1) there is an empirical relation 1/Q=a+b/Δp between flux Q and difference pressure Δp in a porous membrane, 2) there exists a limit of flux Q in porous membrane and this shows drastic decrease with reduction in specific surface area, 3) pore size distribution changes remarkably with increasing the thickness of metal coating film on porous membrane, and 4) especially the coating effect appears in the pore size range from 20A to 80A.It was found that the gas permeability is affected largely by the change of pore size distribution.