Multilayer Composite Membranes Research Articles

中空糸膜を用いた海洋二酸化炭素の測定

In order to measure the CO 2 mixing ratios in air equilibrated with seawater (xCO 2 S ), we tested a multi-layered composite hollow-fiber membrane (MHF) module aboard the TS Hokuto-maru in the North Pacific in January-February 1996 and July-August 1996. The MHF module is much smaller (300 cm 3 ) than the currently used shower-head type equilibrator (110 dm 3 installation volume). The mean difference in xCO 2 S (ΔxCO 2 S ) values between the two systems determined 14 minutes apart was 1.6 ppm with a standard deviation of 2.2 ppm (n = 73) for the southbound cruise in January, and -1.9 ppm with a standard deviation of 1.8 ppm (n = 103) for the northbound cruise in February, 1996. The difference in average ΔxCO 2 S between the two legs was mainly caused by the effect of water temperature difference between the shower-head type equilibrator and the MHF module. By taking into account the effect on xCO 2 S of water-temperature difference between the two equilibrators, the mean ΔxCO 2 S was as low as 0.1 ppm (n = 732) with a standard deviation of 3.7 ppm for the cruise in July-August 1996. These results indicate that no systematic difference exists between the two equilibrators. The MHF has potential for future use as an equilibrator that is compact and easy to install.

Multilayer ultrathin-film composite membranes for oxygen enrichment

Multilayer composite membranes were made of poly(4-methylpentene-1) (PMP), an ethyl cellulose (EC) + heptyl cellulose (HC) blend, polycarbonate (PC), polysulfone, poly(2,6-dimethylphenylene oxide), cellulose triacetate ultrathin films as selective layers, and polysulfone, poly(ether sulfone), and poly(sulfone amide) ultrafiltration membranes with a 10–45 nm pore size and 100–120 μm thickness as porous support layers. The effects of the ultrathin-film type and its casting solution concentration, operating pressure, temperature, as well as time on the oxygen-enriched air (OEA) flux and oxygen concentration in the OEA permeated in a single step through the composite membranes were investigated using a constant pressure—variable volume method. The OEA flux increases significantly with an increasing transmembrane pressure difference and operating temperature. The oxygen concentration in the OEA also increases with an increasing pressure difference but decreases slightly with an increasing operating temperature. In long-term tests, the oxygen-enrichment properties were maintained almost constant for as long as 170 h. The composite membranes consisting of the bilayer ultrathin film cast from a more dilute solution (0.11–0.26 wt %) on the porous support with a smaller pore size combine a higher oxygen-enriching ability and a higher stability than do those of monolayer and tetralayer ultrathin films. The maximum OEA flux and oxygen concentration produced at 20–75°C and a 500 kPa transmembrane pressure difference in a single pass across the PMP/98EC + 2HC bilayer and PC bilayer ultrathin-film composite membranes are 3.1 × 10−3 cm3(STP)/s cm2 and 50%, respectively. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2139–2147, 1997

Multilayer ultrathin‐film composite membranes for oxygen enrichment

Multilayer composite membranes were made of poly(4-methylpentene-1) (PMP), an ethyl cellulose (EC) + heptyl cellulose (HC) blend, polycarbonate (PC), polysulfone, poly(2,6-dimethylphenylene oxide), cellulose triacetate ultrathin films as selective layers, and polysulfone, poly(ether sulfone), and poly(sulfone amide) ultrafiltration membranes with a 10–45 nm pore size and 100–120 μm thickness as porous support layers. The effects of the ultrathin-film type and its casting solution concentration, operating pressure, temperature, as well as time on the oxygen-enriched air (OEA) flux and oxygen concentration in the OEA permeated in a single step through the composite membranes were investigated using a constant pressure—variable volume method. The OEA flux increases significantly with an increasing transmembrane pressure difference and operating temperature. The oxygen concentration in the OEA also increases with an increasing pressure difference but decreases slightly with an increasing operating temperature. In long-term tests, the oxygen-enrichment properties were maintained almost constant for as long as 170 h. The composite membranes consisting of the bilayer ultrathin film cast from a more dilute solution (0.11–0.26 wt %) on the porous support with a smaller pore size combine a higher oxygen-enriching ability and a higher stability than do those of monolayer and tetralayer ultrathin films. The maximum OEA flux and oxygen concentration produced at 20–75°C and a 500 kPa transmembrane pressure difference in a single pass across the PMP/98EC + 2HC bilayer and PC bilayer ultrathin-film composite membranes are 3.1 × 10−3 cm3(STP)/s cm2 and 50%, respectively. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2139–2147, 1997

Calculation of the intrusion depth and its effects on microporous composite membranes

The intrusion of a polymer solution into microporous substrates may have a detrimental effect on the performance of air separation membranes. An extremely simple equation has been derived in this paper for the calculation of intrusion depth in a multi-layer microporous composite membrane. A modified resistance model has also been proposed in order to calculate the intrusion effects on microporous composite membrane performance. When comparing the calculated results to the previous experimental data on 6FDA-polyimide/polyacrylonitrile (PAN) hollow fibers, the new model accurately predicts the air-separation performance of multilayer microporous composite membranes. However, this model is only valid if the surface-porosity ratio multiplying the permeability difference (between the gutter and the substrate) is much greater than the substrate permeability.

Selective permeation of carbon dioxide through plasma polymerized membrane from diisopropylamine

For the purpose of the selective separation of CO 2 over CH 4, plasma polymerized membranes were prepared. They were multilayer composite membranes consisting of a top plasma polymer layer and a substrate consisting of a silicone skin layer and a porous polyimide support. As monomer, diisopropylamine was mainly used in order to utilize the acid-base interaction between CO 2 and amino groups. The separation coefficient and the permeation rate obtained were 17 and 1.5 × 10 −10 kmol/m 2s Pa (=4.5 × 10 −4 cm 3/cm 2s cmHg). This high permeation rate was characteristic of the plasma polymerized membrane which can be made very thin. The effects of the plasma conditions such as power input, monomer flow rate and plasma deposition time on the membrane properties were investigated in detail. It is suggested that the permeation of CO 2 can be explained by the partial immobilization model based on the acid-base interaction between CO 2 and amino groups incorporated into the membranes. The obtained membrane was stable for as long as 25 days. The structures of the plasma polymers were analyzed by FT-IR and XPS measurements. The change of the selectivity corresponded well to the changes of the amounts of nitrogen incorporated into the membrane.

Preparation of composite membranes by a spin coating process

The formation of composite membranes on a laboratory scale by spin coating a selective layer of poly (4-methyl-1-pentene) (PMP) onto a microporous polysulfone support is described. In most cases the support had been precoated with an intermediate layer of poly (dimethyl siloxane) (PDMS). The thickness of the PMP layer, determined indirectly from gas flux measurements on the composite membrane, can be controlled within certain limits by varying the spinning speed, the coating solution concentration or the number of selective layers coated onto the substrate. Coated skin thickness varies approximately with the inverse of the square root of spin speed and with the second power of the coating solution concentration. The model coefficients compare well with those of models proposed for the production of photoresists in which polymer films are spin coated onto non-porous substrates. Gas permeation characteristics of the composite membranes were adequately described by a series resistance model. Composite membranes made without a PDMS intermediate layer required more than one layer of the selective polymer to bridge the larger pores and ensure a defect-free skin. For thin selective layers, these membranes have selectivities somewhat higher thanthat of PMP, since the PSF matrix of the substrate participates in the separation. Thus, multilayer composite membranes formed directly on microporous PSF substrates can be superior to composites with a PDMS intermediate layer.

Long-Term Respiratory Assistance Using a Right Ventricular Assist Device System and a Membrane Oxygenator

A new method for long-term respiratory assistance using a right ventricular assist device (RVAD) system and a membrane oxygenator (MO) was designed and evaluated. An air-driven RVAD was implanted between the right atrium and the pulmonary artery in five goats and an MO was set on the outlet conduit of the RVAD 2 weeks postoperatively. Two types of MOs [the SciMed (Life Systems) silicone sheet MO and a prototype MO using a novel multilayered composite membrane] were used in this study. Respiratory support with this system under systemic heparinization could be conducted for 4-8 days without major problems accompanied with conventional extracorporeal membrane oxygenation (ECMO) such as surgical bleeding, destruction of the blood components, serum leakage, insufficient bypass flow, and fatal systemic thrombosis. This method opened the possibility for ECMO to be used as a bridge before lung or heart-lung transplantation.

A Novel Method for Long-term Respiratory Support

The authors designed a new extracorporeal membrane oxygenation (ECMO) method using a right ventricular assist device (RVAD) system and a membrane oxygenator (MO). An air-driven diaphragm type RVAD was implanted between the right atrium and the pulmonary artery in five goats, and an MO was set on the outlet conduit of the RVAD 2 weeks postoperatively. The MOs used in this study are silicon sheet MOs and prototype MOs using a novel multilayered composite membrane. Respiratory support with this system, under systemic heparinization, could be conducted for 4-8 days without major problems. This method solved several difficulties with ECMO, such as surgical bleeding, serum leakage, destruction of the blood components from the pump system, inadequate bypass flow, and fatal systemic thrombosis. This method is suitable for long-term respiratory support, especially as a bridge before lung or heart-lung transplantation.

A Novel Method for Long-term Respiratory Support

The authors designed a new extracorporeal membrane oxygenation (ECMO) method using a right ventricular assist device (RVAD) system and a membrane oxygenator (MO). An air-driven diaphragm type RVAD was implanted between the right atrium and the pulmonary artery in five goats, and an MO was set on the outlet conduit of the RVAD 2 weeks postoperatively. The MOs used in this study are silicon sheet MOs and'prototype MOs using a novel multilayered composite membrane. Respiratory support with this system, under systemic heparinization, could be conducted for 4–8 days without major problems. This method solved several difficulties with ECMO, such as surgical bleeding, serum leakage, destruction of the blood components from the pump system, inadequate bypass flow, and fatal systemic thrombosis. This method is suitable for long-term respiratory support, especially as a bridge before lung or heart-lung transplantation.

Analysis and construction of multilayer composite membranes for the separation of gas mixtures

Etude de trois types de membranes composites: membranes a deux couches [PAS(Poly(AminoSiloxane))/PS(PolySulfone) et PPO(Poly(dimethyl-2,6 p-phenylene oxyde))/PS] et membranes a trois couches [PPO/PAS/PS]

Development and in vitro evaluation of a novel multilayered composite hollow fiber membrane for artificial lungs

Development and in vitro evaluation of a novel multilayered composite hollow fiber membrane for artificial lungs

Diffusion and permeation of vapors in composite polymer thin films

The moisture barrier properties of polyimide (PI) thin films used for passivation in microelectronic devices are poorer than those of many other polymers. The enhancement of the barrier properties of PI films obtainable by coating them with polymers of lower permeability to form multilayer composite membranes was investigated. In this paper we report a study of the diffusion and permeation of water vapor in four composite PI/polymer thin films: PI/polyethylene, PI/polyethylene-acrylic acid, PI/polyvinylidene fluoride and PI/poly(chloro- p-xylylene). The temperature-dependent permeability coefficient of single-layer and composite thin films was measured and found to follow the Arrhenius relation with low activation energies (lower than 6 kcal mol −1). Enhancement in the barrier properties by a factor of 4–6 at 30°C is attained when 2–3 μm PI films are coated with 2 μm films of the four polymers investigated.