Increment Of Permeability Research Articles

Study of electrical and magnetic properties of Ni–Zn–Mg ferrite system

Polycrystalline nickel–zinc ferrites of chemical formula Ni 0.65-x Mg x Zn 0.35 Fe 2 O 4 (x = 0.00 to 0.2 in steps of 0.04) have been prepared by conventional ceramic technique. Calcination and sintering of all samples have been carried out in air atmosphere at 950°C and 1250°C, respectively, followed by natural cooling to room temperature. All the samples were characterized by the X-ray diffraction (XRD) for structure determination. These samples were then investigated for their magnetic and electric properties, including saturation magnetization, Curie temperature, initial permeability measurements and DC electrical resistivity. Porosity was decreased drastically from 15% to 5% showed better quality of the sintered samples. There were increments in initial permeability and DC electrical resistivity throughout the series of samples. Variations in the observed properties as a function of magnesium concentration have been discussed in light of the existing understanding.

Foliar trichome-aided formaldehyde uptake in the epiphytic Tillandsia velutina and its response to formaldehyde pollution

Epiphytic Tillandsia (Bromeliaceae) species have been found to be efficient biomonitors of atmospheric heavy metals and persistent organic pollutants, but have not been used to monitor or remove the primary indoor atmospheric pollutant formaldehyde (FA). The absorptive capacity of Tillandsia trichomes is well-established, but potential secondary effects of foliar trichomes on gas exchange remain unclear. Our study investigated whether Tillandsia species can absorb FA efficiently and if the leaf trichomes function to improve FA uptake, using Tillandsia velutina. Plants with intact trichomes, decreased FA concentration by 48.42% in 12h from 1060μgm−3 to 546.67μgm−3, while FA concentration decreased only by 22.51% in the plants without trichomes. Moreover, the more trichomes removed from the leaves, the lower the capability of FA uptake per unit leaf area, which suggested that T. velutina was capable of absorbing a large amount of FA via the leaves and specialized trichomes facilitated the whole leaf tissue FA absorption. In addition, all plants exposed to FA were chloric, had a reduction in measured leaf chlorophyll, and an increment in permeability of plasma membranes. However, plants in which trichomes had been removed declined or increased more quickly than plants with intact trichomes, indicating Tillandsia leaf trichomes also give the leaves some protection against this toxin.

144: Breast cancer tumor secreted factors induce both endothelial activation and increment of vascular permeability in vitro

144: Breast cancer tumor secreted factors induce both endothelial activation and increment of vascular permeability in vitro

SPEEK/amine-functionalized TiO2 submicrospheres mixed matrix membranes for CO2 separation

Mixed matrix membranes (MMMs) composed of sulfonated poly(ether ether ketone) (SPEEK) and amine-functionalized titania submicrospheres were prepared. TiO2 submicrospheres (~300nm) were amine-functionalized through a facile two-step method by using dopamine (DA) and polyethyleneimine (PEI) in succession. The resultant TiO2–DA–PEI microspheres were incorporated into SPEEK with a sulfonation degree of 67%. Grafting PEI with abundant amine groups onto the titania fillers remarkably increased the content of facilitated transport sites in the membranes, leading to an increment in both gas permeability and selectivity. High humidity also contributed to the facilitated transport of CO2 via the generation of HCO3−. The highest ideal selectivities of the SPEEK/TiO2–DA–PEI membranes for CO2/CH4 and CO2/N2 were 58 and 64, respectively, with a CO2 permeability of 1629Barrer. Besides, the mechanical and thermal stabilities of the membranes were also enhanced compared to pure SPEEK membrane.

PIM-1 as an organic filler to enhance the gas separation performance of Ultem polyetherimide

An assortment of Ultem/PIM-1 polymer blends was prepared and their transport properties to a series of gases were studied. Good dispersion between the PIM-1 and Ultem phases was found when the PIM-1 loading was low (<20wt%) or high (>90wt%). A slight shift of Tg was observed when the PIM-1 loading increased from 0wt% to 50wt%, suggesting likely partially miscibility. The molecular-level interactions were further confirmed by the FTIR and XRD data, where shifts of peaks were detected at several compositions. Gas transport properties of pure gases including He, N2, O2, CH4, CO2 for all polymer blends and mixed gases including CO2/CH4 (50/50) and CO2/N2 (50/50) gas pairs for Ultem/PIM-1 (90:10) and Ultem/PIM-1 (80:20) blends were explored. Considerable increments in gas permeability were observed by adding only 5 or 10wt% PIM-1 without much compromising gas pair selectivity, i.e., the CO2 permeability increased impressively over 47% and 167%, respectively, compared with the pristine Ultem. When comparing the gas permeation properties with the predictions from semi-logarithm and Maxwell equations, they follow nicely with the semi-logarithm addition when the PIM-1 loadings are low (<20wt%), indicting relatively homogenous blends at these compositions, while the transport properties match closely with the Maxwell prediction at high PIM-1 loadings (>90wt%) due to the good dispersion of Ultem inside PIM-1. This study opens up the potential of employing PIM-1 as an organic filler to improve the permeability of low permeable materials for other industrial membrane applications.

Mixed matrix membranes based on NH2-functionalized MIL-type MOFs: Influence of structural and operational parameters on the CO2/CH4 separation performance

Mixed matrix membranes (MMMs) based on NH2-functionalized MIL-53(Al) and MIL-101(Al) MOFs dispersed in polysulfone (PSF) and polyimide (PI) polymers have been investigated. The MOF loading was varied in the range of 8–25wt.%, while membranes with different thicknesses were obtained by two casting methodologies. The synthesized membranes were tested in the separation of CO2 from an equimolar CO2/CH4 mixture. At steady operation (T=35°C, ΔP=3bar), incorporation of the MOF filler has a positive effect on the separation performance which consists of a moderate enhancement of the separation selectivity, in certain cases along with an improvement in CO2 permeability. In general, higher separation factors and CO2 permeabilities are achieved with PI than with PSF. Our study reveals the relevance of the membrane thickness for both the separation performance under given conditions and the sensitivity to other structural and operational variables. The incorporation of NH2-MIL-53(Al) as filler in PI-based MMMs has a larger effect, particularly a beneficial increment in CO2 permeability at constant separation factor, for thinner membranes casted in a Doctor Blade system. This is tentatively attributed to the partial preservation of the original narrow pore configuration of this flexible MOF, unlike in thicker membranes casted in the absence of shear forces. Although improvements in the separation performance remain moderate with respect to the neat PI counterpart, the benefits of the incorporation of MOF as filler become more apparent at high pressures: while for pure polymeric membranes a decrease in the separation factor is observed at increasing ΔP, MMMs maintain large separation factors up to transmembrane pressures as high as 12bar, highlighting the application potential of these composites. On the other hand, reducing the membrane thickness limits the MOF loading that can be incorporated before the mechanical stability of the membrane becomes compromised. It also enlarges the impact of the temperature and trans-membrane pressure on the separation performance. Overall, this work reveals that an interplay between structural and operational variables determines the performance of MOF MMMs and calls for a multi-variable optimization to advance this technology.

Production and permeability of porous Si3N4 ceramics produced by starch addition

In this study, the possibility of enhancing permeability of porous Si3N4 ceramics was studied by using pore former additive (potato starch; 0–30 vol.%). The open porosity of samples changed between 52 and 66% as the mean pore channel size values ranged from 0.9 to 4 μm. Increasing starch addition provides bimodal distribution of pore size channels by accompanying abrupt increment in non-Darcian permeability. k2 value rised from 8.7 × 10−10 m to 30.1 × 10−10 m.

The relative impact of forest patch and landscape attributes on black howler monkey populations in the fragmented Lacandona rainforest, Mexico

Land-use change is forcing many animal populations to inhabit forest patches in which different processes can threaten their survival. Some threatening processes are mainly related to forest patch characteristics, but others depend principally on the landscape spatial context. Thus, the impact of both patch and landscape spatial attributes needs to be assessed to have a better understanding of the habitat spatial attributes that constraint the maintenance of populations in fragmented landscapes. Here, we evaluated the relative effect of three patch-scale (i.e., patch size, shape, and isolation) and five landscape-scale metrics (i.e., forest cover, fragmentation, edge density, mean inter-patch isolation distance, and matrix permeability) on population composition and structure of black howler monkeys (Alouatta pigra) in the Lacandona rainforest, Mexico. We measured the landscape-scale metrics at two spatial scales: within 100 and 500 ha landscapes. Our findings revealed that howler monkeys were more strongly affected by local-scale metrics. Smaller and more isolated forest patches showed a lower number of individuals but at higher densities. Population density also tended to be positively associated to matrices with higher proportion of secondary forests and arboreal crops (i.e. with greater permeability), most probably because these matrices can offer supplementary foods. The immature-to-female ratio also increased with matrix permeability, shape complexity, and edge density; habitat characteristics that can increase landscape connectivity and sources availability. The prevention of habitat loss and isolation, and the increment of matrix permeability are therefore needed for the conservation of this endangered Neotropical mammal.

Evaluation and modeling of gas permeability changes in anthracite coals

The gas permeability of anthracite coal is altered as a result of the effective stress increase, the coal matrix shrinkage and the gas slippage that occur during the gas pressure depletion process. This paper describes an investigation of changes in the adsorbing-gas (CO2) permeability of three anthracite coal cores (samples A, B and C). The changes in permeability under a constant confining stress condition (4.3MPa) were found to be distinct for the three cores, and these observations are considered as the superimposed results of the three effects based on the following findings. During the gas pressure depletion: (a) the permeability is negatively proportional to the effective stress, and the slopes of the straight lines are near unity when the mean gas pressures are greater than 0.2–0.4MPa; (b) the permeability increment induced by the gas slippage levels off to an approximately constant value (core A, 0.5μD; core B, 0.6μD; core C, 0.02μD) when the mean gas pressure is greater than 0.8MPa and subsequently becomes more significant at pressures less than 0.8MPa; (c) the matrix shrinkage-induced permeability increment increases linearly for cores A and B but increases logarithmically for core C; and (d) the effect on the permeability of the effective stress predominates for core A, but for core C, the effect of the matrix shrinkage is most significant. Furthermore, an empirical model that predicts the adsorbing-gas permeability change was proposed as a function of the permeability increments caused by the effective stress, the matrix shrinkage and the gas slippage at each gas pressure under a constant confining stress condition, and can be mathematically expressed as: kgt=koi+Δksli(pt)+Δkshr(pt)+Δkeff(pt). The results demonstrate that good agreement was achieved between the empirical models and the experimental data.

Developing cross-linked poly(ethylene oxide) membrane by the novel reaction system for H2 purification

In this study, a ‘green” method has been discovered by utilizing the amino functional poly(ethylene oxide) (PEO) and epoxy functional PEO with low molecular weights to synthesis cross-linked membranes for enhancing H2 purification and CO2 capture performance by retarding the crystallinity of semi-crystalline polymer of PEO. The cross-linking reaction can happen simply by mixing two materials without using any solvent. The reaction has been characterized by Fourier transform infrared-attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), solid-state 13C nuclear magnetic resonance (NMR) and the gel content test. Furthermore, X-ray diffraction (XRD) and differential scanning calorimeter (DSC) confirm the amorphous structure of cross-linked PEO membranes, which should benefit the gas transport. The gas transport properties and the plasticizing phenomenon of CO2 have been examined in detail. Interestingly, the investigation on CO2 plasticization phenomenon reveals that the cross-linked PEO membrane should be plasticized immediately after the pressure load. The pressure dependence of CO2 permeability in the pressure range from 0.25 atm to 30 atm can be separated into two stages based on the permeability increment although the CO2 permeability continuously increases with the loading pressure. The gas transport results illustrate that CO2 has much larger permeability than that of any tested gas (including H2, N2 and CH4) attributing to the CO2-philic characteristic of ethylene oxide (EO) groups in the cross-linked PEO membrane. The good permeability and selectivity make the developed PEO membrane promising for H2 purification and CO2 capture applications.

Pure and mixed gas CH4 and n-C4H10 permeation in PDMS-fumed silica nanocomposite membranes

Nanocomposite membranes of polydimethylsiloxane (PDMS) with different amounts of fumed silica were synthesized over a porous support of polyacrylonitrile. The prepared membranes were characterized using atomic force microscopy and thermal gravimetric analysis. AFM results indicated the nanoscale dispersion of silica particles in polymer matrix. TGA results indicated that increasing the silica content enhances the thermal stability of membranes. Permeation of methane and n-butane single gases at different upstream pressures and also permeation of a gas mixture containing 3mol% of n-butane in methane were studied and discussed. The results showed that the nanocomposite membrane containing 11wt% of fumed silica exhibited 38% increment in permeability of n-butane and simultaneously 30% increase in selectivity of n-butane over methane. The unusual property enhancement that contradicts to that of conventional filled polymer systems has been discussed based on density of membranes and free volume concept.

Molecular engineering of PIM-1/Matrimid blend membranes for gas separation

Abstract The polymers of intrinsic microporosity have gained the attention as one of the potential materials for membrane gas separation. The contorted ladder-like structure in polymers of intrinsic microporosity, specifically PIM-1 possesses high permeability but with moderate selectivity for O2/N2, CO2/N2 and CO2/CH4 separation. We report here the most convenient and time efficient strategy of tuning the permeability and selectivity by blending PIM-1 with different compositions of Matrimid. In this work, the physical properties, phase behavior and gas transport properties of PIM-1/Matrimid blends have been explored. The polarized light microscope (PLM) analyses evidence that most of the PIM-1/Matrimid blends reveal partially miscible behavior. The inclusion of PIM-1 in the Matrimid matrix results in a substantial increase in gas permeability and a slight decrease in selectivity. The additions of 5 and 10 wt% PIM-1 into Matrimid induce the permeability increments of 25% and 77%, respectively from the original 9.6 to 12 and 17 Barrer without compromising its CO2/CH4 selectivity. For O2/N2 separation, the incorporation of a small amount of Matrimid (e.g., 5–30 wt%) into PIM-1 promotes a fair increase in selectivity and drives the overall gas separation performance surpassing or close to the upper bound. At binary gas tests of CO2/CH4 (50%/50%), the 30 wt% PIM-1 in Matrimid membrane has a CO2 permeability of 50 Barrer and a CO2/CH4 selectivity of 31.

Nimodipine Attenuation of Early Brain Dysfunctions Is Partially Related to its Inverting Acute Vasospasm in a Cisterna Magna Subarachnoid Hemorrhage (SAH) Model in Rats

ABSTRACTSubarachnoid hemorrhage (SAH)-induced brain injury is highly related to neurological deficits and mortality. Regional cerebral blood flow (rCBF) changes and vasoconstriction are two complications that occur soon after SAH experimentally. In this study we investigated the changes in rCBF and vertebro-basilar arterial diameter in a cisterna megna SAH model in Sprague–Dawley rats and intended to explore whether improving early rCBF reduction and cerebral vasospasm could contribute to alleviating blood–brain barrier (BBB) dysfunction. In rats for rCBF, vasospasm and BBB permeability assessments, nimodipine (NDP) or saline was administered intravenously 5 minutes after SAH. rCBF within the first 60 minutes after SAH was measured by laser Doppler flowmetry. BBB permeability indexed by Evans Blue extravasation was assessed 4 hours after SAH. Angiography for the caliber changes of the vertebro-basilar artery were conducted 30 minutes post SAH. Pronounced rCBF reduction and vasospasm were observed soon after SAH, followed by BBB permeability increment. NDP administration could improve rCBF and attenuate vasospasm, followed by the alleviation of BBB permeability. Our results demonstrate that early improvement of cerebral circulation by NDP may contribute to the reduction in brain injury indexed by BBB disruption.

Extended power-law scaling of air permeabilities measured on a block of tuff

Abstract. We use three methods to identify power-law scaling of multi-scale log air permeability data collected by Tidwell and Wilson on the faces of a laboratory-scale block of Topopah Spring tuff: method of moments (M), Extended Self-Similarity (ESS) and a generalized version thereof (G-ESS). All three methods focus on q-th-order sample structure functions of absolute increments. Most such functions exhibit power-law scaling at best over a limited midrange of experimental separation scales, or lags, which are sometimes difficult to identify unambiguously by means of M. ESS and G-ESS extend this range in a way that renders power-law scaling easier to characterize. Our analysis confirms the superiority of ESS and G-ESS over M in identifying the scaling exponents, ξ(q), of corresponding structure functions of orders q, suggesting further that ESS is more reliable than G-ESS. The exponents vary in a nonlinear fashion with q as is typical of real or apparent multifractals. Our estimates of the Hurst scaling coefficient increase with support scale, implying a reduction in roughness (anti-persistence) of the log permeability field with measurement volume. The finding by Tidwell and Wilson that log permeabilities associated with all tip sizes can be characterized by stationary variogram models, coupled with our findings that log permeability increments associated with the smallest tip size are approximately Gaussian and those associated with all tip sizes scale show nonlinear variations in ξ(q) with q, are consistent with a view of these data as a sample from a truncated version (tfBm) of self-affine fractional Brownian motion (fBm). Since in theory the scaling exponents, ξ(q), of tfBm vary linearly with q we conclude that nonlinear scaling in our case is not an indication of multifractality but an artifact of sampling from tfBm. This allows us to explain theoretically how power-law scaling of our data, as well as of non-Gaussian heavy-tailed signals subordinated to tfBm, are extended by ESS. It further allows us to identify the functional form and estimate all parameters of the corresponding tfBm based on sample structure functions of first and second orders.

Albino strains of Ophiostoma spp. fungi effect on radiata pine permeability

Albino strains of Ophiostoma piliferum, Ophiostoma piceae and Ophiostoma floccosum used as single strain and in mixtures are tested for their abilities to increase the permeability of radiata pine sapwood after 2 and 4 weeks of incubation. The bio-treatments yielded permeability increments up to 1.9 and 2.4 times controls after 2 and 4 weeks, respectively. The fungus type involved in the treatments as well as the incubation time appeared as significant factors. Results also suggest that combinations of albino Ophiostoma spp. fungi could increase permeability to higher levels than individual ones, hinting at a possible synergistic relationship among them. Furthermore, treatments with a high concentration of O. floccosum seem particularly successful. Simultaneously to the increment of permeability such bio-treatment might also offer protection against blue sap-stain. Further research is recommended to refine and find an optimum time of incubation, as well as the most effective combination and concentration of fungi.

Fenofibric acid prevents retinal pigment epithelium disruption induced by interleukin-1β by suppressing AMP-activated protein kinase (AMPK) activation

The mechanisms involved in the beneficial effects of fenofibrate on the development and progression of diabetic macular oedema (DMO) remain to be elucidated. To shed light on this issue we have explored the effect of fenofibric acid on the barrier function of human retinal pigment epithelium (RPE) cells. ARPE-19 cells (a human RPE line) were cultured for 18 days under standard conditions and under conditions leading to the disruption of the monolayer (D-glucose, 25 mmol/l, with IL-1β, 10 ng/ml, added at days 16 and 17). Fenofibric acid, 25 μmol/l and 100 μmol/l, was added on the last 3 days of the experiment (one application/day). RPE cell permeability was evaluated by measuring apical-basolateral movements of FITC-dextran (40 kDa). The production of tight junction proteins and AMP-activated protein kinase (AMPK) phosphorylation was assessed by western blot. Immunohistochemical studies of tight junction proteins and small interfering RNA transfection to AMPK were also performed in ARPE-19 monolayers. Treatment of ARPE-19 cells with fenofibric acid significantly reduced the increment of permeability and the breakdown of the ARPE-19 cell monolayer induced by D-glucose, 25 mmol/l, and IL-1β, 10 ng/ml, in a dose-dependent manner. This effect was unrelated to changes in the content of tight junction proteins. Fenofibric acid prevented the activation of AMPK induced by IL-1β and the hyperpermeability induced by IL-1β was blocked by silencing AMPK. Disruption of RPE induced by IL-1β is prevented by fenofibric acid through its ability to suppress AMPK activation. This mechanism could be involved in the beneficial effects of fenofibrate on DMO development.

Effects of early endotoxemia and dextran-induced anaphylaxis on the size selectivity of the glomerular filtration barrier in rats

This study was performed to investigate the glomerular permeability alterations responsible for the microalbuminuria occurring in endotoxemia and during anaphylactic shock. In anesthetized Wistar rats, the left ureter was catheterized for urine collection while, simultaneously, blood access was achieved. Endotoxemia was induced by lipopolysaccharide (LPS) from Escherichia coli, and glomerular permeability was assessed at 60 and 90 (n = 7) and 120 (n = 7) min. Anaphylaxis was induced by a bolus dose of Dextran-70, and glomerular permeability assessed at 5 min (n = 8) and 40 min (n = 9). Sham animals were followed for either 5 or 120 min. The glomerular sieving coefficients (theta) to fluorescein isothiocyanate-Ficoll (70/400) were determined from plasma and urine samples and assessed using size-exclusion chromatography (HPLC). After start of the LPS infusion (2 h), but not at 60 or 90 min, theta for Ficoll(70A) had increased markedly [from 2.91 x 10(-5) +/- 6.33 x 10(-6) to 7.78 x 10(-5) +/- 6.21 x 10(-6) (P < 0.001)]. In anaphylaxis, there was a large increase in theta for Ficolls >60 A in molecular radius already at 5 min, but the glomerular permeability was completely restored at 40 min. In conclusion, there was a transient, immediate increment of glomerular permeability in dextran-induced anaphylaxis, which was completely reversible within 40 min. By contrast, endotoxemia caused an increase in glomerular permeability that was manifest first after 2 h. In both cases, theta to large Ficoll molecules were markedly increased, reflecting an increase in the number of large pores in the glomerular filter.

Proline and glycinebetaine induce antioxidant defense gene expression and suppress cell death in cultured tobacco cells under salt stress

Salt stress causes oxidative damage and cell death in plants. Plants accumulate proline and glycinebetaine (betaine) to mitigate detrimental effects of salt stress. The aim of this study was to investigate the protective effects of proline and betaine on cell death in NaCl-unadapted tobacco (Nicotiana tabacum) Bright Yellow-2 suspension-cultured cells subjected to salt stress. Salt stress increased reactive oxygen species (ROS) accumulation, lipid peroxidation, nuclear deformation and degradation, chromatin condensation, apoptosis-like cell death and ATP contents. Neither proline nor betaine affected apoptosis-like cell death and G(1) phase population, and increased ATP contents in the 200mM NaCl-stressed cells. However, both of them effectively decreased ROS accumulation and lipid peroxidation, and suppressed nuclear deformation and chromatin condensation induced by severe salt stress. Evans Blue staining experiment showed that both proline and betaine significantly suppressed increment of membrane permeability induced by 200mM NaCl. Furthermore, among the ROS scavenging antioxidant defense genes studied here, mRNA levels of salicylic acid-binding (SAbind) catalase (CAT) and lignin-forming peroxidase (POX) were found to be increased by proline and betaine under salt stress. It is concluded that both proline and betaine provide a protection against NaCl-induced cell death via decreasing level of ROS accumulation and lipid peroxidation as well as improvement of membrane integrity.

Synthesis of hexafluoroisopropylidene isophthalic polyesters and copolyesters and the relationship between their structure and gas transport properties

AbstractTwo aromatic polyesters and three copolyesters were synthesized by interfacial polycondensation using 4,4′‐(hexafluoroisopropylidene)diphenol (HFD) and two phthalic dichlorides, isophthaloyl dichloride (ISO) and 5‐tertbutyl‐isophthaloyl dichloride (TERT). The polymers obtained were soluble in common chlorinated solvents. The properties of these aromatic polyesters and copolyesters were characterized by FTIR, density, inherent viscosity, TGA, and DSC. Thermal properties such as glass transition temperature, onset of decomposition, and thermal stability of the homopolymer, poly(hexafluoroisopropilydene)5‐tertbutylisophthalate (HFD/TERT), were higher than those of homopolymer poly(hexafluoroisopropilydene)isophthalate (HFD/ISO). Thermal properties of the copolyesters HFD/TERT‐co‐HFD/ISO depend upon the amounts of the tertbutyl group HFD/TERT, present in the copolymer. Gas permeability coefficients of all polyarylates were measured at 35°C. The effect of different concentrations of the bulky tertbutyl group at the 5‐position in the isophthaloyl moiety on He, O2, N2, and CO2 permeability, diffusion, and solubility coefficients were determined. Gas permeability and diffusivity increase as the concentration of TERT moiety increases in the copolymers. The results indicate that polymers containing the largest amounts of the bulky lateral tertbutyl group show the highest gas permeability. The increment in gas permeability and diffusivity produces a decrease in selectivity, which is attributed to the effect of the large pendant tertbutyl groups in the aromatic polyesters and copolyesters, which decrease the chain packing efficiency and induce a larger fractional free volume. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2207–2216, 2007

Enhanced gas permeability of cellulose acetate membranes under microwave irradiation

In this study, the permeability coefficients of various gases for a cellulose acetate (CA) and polystyrene (PS) membrane were measured under microwave irradiation by using a handmade apparatus, which can irradiate a microwave (2450 MHz). Permeability in the PS membrane that have no polar functional groups was not affected by irradiating microwave, while permeability coefficients for various gases in the CA membrane that have polar functional groups were more than these without microwave irradiation. Further, the degree of increment in permeability coefficients with microwave depended on kinds of permeation gas. The increment of Kr permeability under microwave irradiation was most remarkable. It could be expected that microwave accelerate the mobility of polar functional groups in polymeric membranes, and then, gas permeability improve due to an extension of diffusion path in membranes.