Permeability Of Polymer Membranes Research Articles

Permeability of Polymer Membranes Based on Polyimides Towards Helium

Permeability of Polymer Membranes Based on Polyimides Towards Helium

Effect of Nanofillers on Properties and Pervaporation Performance of Nanocomposite Membranes: A Review.

In recent years, a well-known membrane-based process called pervaporation (PV), has attracted remarkable attention due to its advantages for selective separation of a wide variety of liquid mixtures. However, some restrictions of polymeric membranes have led to research studies on developing membranes for efficient separation in the PV process. Recent studies have focused on preparation of nanocomposite membranes as an effective method to improve both selectivity and permeability of polymeric membranes. The present study provides a review of PV nanocomposite membranes for various applications. In this review, recent developments in the field of nanocomposite membranes, including the fabrication methods, characterization, and PV performance, are summarized.

Evaluation of Hydrogen Permeability of Polymer Membranes

Evaluation of Hydrogen Permeability of Polymer Membranes

Percolation Effects in Mixed Matrix Membranes with Embedded Carbon Nanotubes.

Polymeric membranes with embedded nanoparticles, e.g., nanotubes, show a significant increase in permeability of the target component while maintaining selectivity. However, the question of the reasons for this behavior of the composite membrane has not been unequivocally answered to date. In the present work, based on experimental data on the permeability of polymer membranes based on Poly(vinyl trimethylsilane) (PVTMS) with embedded CNTs, an approach to explain the abnormal behavior of such composite membranes is proposed. The presented model considered the mass transfer of gases and liquids through polymeric membranes with embedded CNTs as a parallel transport of gases through the polymeric matrix and a "percolation" cluster-bound regions around the embedded CNTs. The proposed algorithm for modeling parameters of a percolation cluster of embedded tubular particles takes into account an agglomeration and makes it possible to describe the threshold increase and subsequent decrease permeability with increasing concentration of embedded particles. The numerical simulation of such structures showed: an increase in the particle length leads to a decrease in the percolation concentration in a matrix of finite size, the power of the percolation cluster decreases significantly, but the combination of these effects leads to a decrease in the influence of the introduced particles on the properties of the matrix in the vicinity of the percolation threshold; an increase in the concentration of embedded particles leads to an increase in the probability of the formation of agglomerates and the characteristic size of the elements that make up the percolation cluster, the influence of individual particles decreases and the characteristics of the percolation transition determine the ratio of the sizes of agglomerates and matrix; and an increase in the lateral linear dimensions of the matrix leads to a nonlinear decrease in the proportion of the matrix, which is affected by the introduced particles, and the transport characteristics of such MMMs deteriorate.

Toward predictive permeabilities: Experimental measurements and multiscale simulation of methanol transport in Nafion

AbstractA polymer membrane's permeability to solutes determines its suitability for various applications: a permeability value is essential for predicting performance in diverse contexts. Using aqueous methanol permeation through Nafion as an example, we describe a methodology for determining membrane permeability that accounts for boundary layer effects and the possibility of swelling. For the materials and apparatus used herein, analysis of a permeance measurement and computational fluid dynamics simulations show that the mass transfer boundary layer is on the order of ones to tens of microns. The data are used to develop and validate a multiscale model describing solute permeation through a hydrated membrane as a series of physical mechanistic steps: reversible adsorption from solution at the membrane interface, diffusion driven by a concentration gradient within the membrane, and reversible desorption into solution at the opposite membrane interface. The validated model is used to predict methanol transport across a solar‐driven CO2 reduction device and to assess the impact of polymer changes on the measured value. The approach of combining experimental data, computational fluid dynamics, and the mechanistic multiscale model is expected to provide more accurate analysis of membrane permeation data in cases with polymer swelling or unusual device geometries, among others.

Development of highly gas-permeable polymers by metathesis copolymerization of 1-(p-trimethylsilyl)phenyl-1-propyne with tert-butyl and silyl group-containing diphenylacetylenes.

The development of highly gas-permeable membranes is required for gas separation applications. In this study, 1-(p-trimethylsilyl)phenyl-1-propyne (SPP) was copolymerized with diphenylacetylenes bearing tert-butyl (BDPA) and SiMe3 (SDPA) groups at various feed ratios to obtain poly(SPP-co-BDPA) and poly(SPP-co-SDPA) copolymers, respectively. Free-standing membranes were fabricated from toluene solutions of the copolymers, the gas permeability of which increased as the SPP ratio decreased (PO2: 550–2100 barrers). Interestingly, poly(SPP-co-BDPA) and poly(SPP-co-SDPA) at a 1 : 4 ratio of SPP:BDPA and SPP:SDPA, respectively, showed higher permeabilities than the respective homopolymers. Desilylation of the poly(SPP-co-BDPA) membrane increased the gas permeability, whereas desilylation of the poly(SPP-co-SDPA) membrane had the opposite result.

Incorporation of Cu3BTC2 nanocrystals to increase the permeability of polymeric membranes in O2/N2 separation

To increase permeability in O2/N2 separation without compromising selectivity, Cu3BTC2 (or HKUST-1) nanocrystals, which possess well-defined channels and high surface area, were used as the filler for mixed-matrix membrane fabrication. The Cu3BTC2 nanocrystals, which were synthesized at room temperature with a facile method, showed desirable physical properties and porosity comparable to those of a commercial Cu3BTC2 adsorbent (Basolite C300). High-quality mixed-matrix membranes without appreciable defects were successfully fabricated with both Matrimid and polysulfone, which are commercial membrane polymers that suffer from poor permeability. Gas permeation testing revealed that 20 wt% Cu3BTC2 nanocrystals loading dramatically improved the O2 permeability of both polymer membranes (106% for Matrimid and 379% for polysulfone), with modest increases in O2/N2 selectivity. A detailed analysis of diffusivity and solubility showed that the overall O2/N2 diffusion selectivity was improved substantially over that of a neat polymeric membrane with the incorporation of Cu3BTC2 nanocrystals. A comparative study with literature data demonstrated that Cu3BTC2 nanocrystals are far more effective than other metal-organic framework fillers tested to increase permeability in O2/N2 separation.

Separation of Gases by Membranes: The Effects of Pollutants on the Stability of Membranes

Abstract The long-term stability of membranes is determined mainly by their sensitivity to pollutants. Their stability was tested using a novel, multichannel measuring system, which is based on pressure differences. This measuring system is suitable to determine the changes in permeability of polymer membranes. The damaging effects of H2S, BTX and n-dodecane were investigated in terms of polyimide gas separation membranes using nitrogen gas.

Effect of polymers chemical structure on the membrane characteristics

The comparative analysis of gas transport properties and conformational parameters of membranes obtained from two polyimides and polysulfone was made. It was shown that the introduction of a sulfone group instead of a methylene group in the amine component of polyimide leads to an increase in glass transition temperature and of polymer membrane permeability coefficient and a reduction in selectivity. Also it was demonstrated that the solvent used during the preparation of polymer membranes had a significant influence on their gas transport characteristics.

Inorganic particle enhanced polymer hollow fiber membranes with high mechanical properties

Inorganic particle/polymer hollow fiber membranes with different inorganic particle sizes and particle loadings were synthesized and characterized in terms of morphology and mechanical properties. The incorporation of inorganic particles induces the formation of large surface pores in the skin layer yet decreases the pore size of large voids in the support layer. The particle size and particle loading are determining factors in such morphology changes. Moreover, due to the different out-diffusion ability of inorganic particles with different sizes, smaller particles migrated and diffused out from polymer much more easily; therefore nano-sized inorganic particles were usually observed on the top surface of polymer whereas micron-sized inorganic particles were usually partially embedded inside the polymer. As a result of such morphology changes and the intrinsic mechanical properties of inorganic particles, both tensile and compressive properties were improved in such inorganic-polymer composite membranes compared to the pristine membranes. Specifically, the tensile strength can be increased by 47.2% with 1.96 wt% nano-sized alumina whereas the yield compressive strength was enhanced by 55.4% with 76.9 wt% micron-sized alumina in comparison with the pristine polymeric membranes. Besides the improvement of strength, the tensile and compressive Young's modulus was increased and the micron-sized particles are more effective to enhance the Young's modulus than the nano-sized particles. Besides the improvement in mechanical properties, the permeability of polymeric membranes was also enhanced via the inorganic particle incorporation. Therefore, such inorganic-polymer hollow fiber membranes are more promising to be used for practical industrial filtration applications regarding their higher mechanical properties to resist breakage and deformation and their higher permeability in comparison with the polymeric hollow fiber membranes.

New Technique for Measuring and Controlling the Permeability of Polymeric Membranes

Membranes have wide uses in industry and medicine applications. Polymer membranes are important materials because of their high chemical resistance, but they are of weak mechanical resistance against high pressures. Therefore, it was essential to modify a permeability measuring technique free from high pressure application. The current work represented a modification for the permeability measuring technique of membranes, where ionic salt was added with known concentration to water as common solvent and the electrolyte current was measured behind the membrane. The electrolysis current was correlated to the flow rate of water across a polyvinyl alcohol (PVA) membrane. Some other problems were raised such that polarization on electrodes and changes in electrolyte contents during the long time of the slow process. Pulsed potential on electrodes resolved these problems and other associated problems like rush in current and the double layer capacitance effect. An empirical equation was suggested to evaluate the permeability of polymer membranes by this modified method. Easy and accurate measurement of permeability helped authors to change the permeability of PVA membranes by adding copper nano particles in membrane to reduce its permeability, and adding silicone dioxide micro particles to the PVA membranes to increase its permeability. Authors suggested a mechanism for these permeability changes. Scanning electron microscope images for the filled PVA membranes supported the suggested mechanism. International Journal of Science and Engineering Applications Volume 4 Issue 5, 2015, ISSN-2319-7560 (Online) 315 ww.ijsea.com w

Permeability and selectivity of reverse osmosis membranes: Correlation to swelling revisited

Membrane swelling governs both rejection of solutes and permeability of polymeric membranes, however very few data have been available on swelling in water of salt-rejecting reverse osmosis (RO) membranes. This study assesses swelling, thickness and their relation to water permeability for four commercial polyamide (PA) RO membranes (SWC4+, ESPA1, XLE and BW30) using atomic force microscopy (AFM) and attenuated total reflection Fourier transform IR spectroscopy (ATR-FTIR). ATR-FTIR offered a significantly improved estimate of the actual barrier thickness of PA, given AFM is biased by porosity (“fluffy parts”) or wiggling of the active layer or presence of a coating layer. Thus obtained intrinsic permeability (permeability times thickness) and selectivity of aromatic polyamides plotted versus swelling falls well on a general trend, along with previously reported data on several common materials showing RO and NF selectivity. The observed general trend may be rationalized by viewing the polymers as a random composite medium containing molecularly small pores. The results suggest that the combination of a rigid low dielectric matrix, limiting the pore size, with multiple hydrophilic H-bonding sites may be a common feature of RO/NF membranes, allowing both high permeability and selectivity.

Carrier gas flow arrangement based photoacoustic detection method for measuring gas permeability of polymer membranes

This paper describes a membrane permeability measuring set-up based on photoacoustic spectroscopy using continuous carrier gas flow to transport the permeated analyte molecules into a photoacoustic detection cell. The permeability parameters of the sample were determined from the measured permeation curves by using a numerical curve fitting algorithm. The method was applied to different membrane samples for determining methane and carbon-dioxide permeability at various carrier gas flow rates (CFRs). For each sample, a characteristic threshold flow rate (TFR) value can be identified below which a strong dependency of the determined permeation parameters on the CFR was found. For those cases when the CFR value cannot be set to be sufficiently high (i.e. above the TFR value), an extrapolation method was presented giving an accurate estimation of the permeation parameters.

The properties and filtration efficiency of activated carbon polymer composite membranes for the removal of humic acid

To improve the filtration efficiency and permeability of polymer membranes simultaneously during water treatment, different ratios of activated carbon (AC) and polyethylene glycol (PEG) were added into polyphenylsulfone (PPSU)/polyetherimide (PEI) polymers to prepare the novel composite polymer membranes. The results showed that the addition of AC significantly affected the membrane morphology, pore size distribution, porosity, and chemical properties. With this increase in AC concentration, the filtration flux and permeability of the AC/PPSU/PEI/PEG composite membrane improved. The addition of hydrophilic pore-formation agent PEG helped to increase the surface hydrophilicity and porosity of the AC/PPSU/PEI/PEG composite membranes. The intrinsic membrane resistances decreased with the rising concentration of PEG. The optimum component of the AC/PPSU/PEI/PEG composite membrane was 0.25/35/5/6wt.%, and the corresponding membrane permeability and humic acids (HAs) removal efficiency were 184Lm−2h−1 and 80%, respectively.

Transport of a Lipophilic Ionizable Permeant (Capric Acid) Across a Lipophilic Membrane (Silicone Polymer Membrane) from Aqueous Buffered Solutions in the Presence of Hydroxypropyl-β-Cyclodextrin

The present study describes a physical model approach applicable to understanding the transport of highly lipophilic, ionizable drugs across a lipophilic membrane between two aqueous compartments in the presence of a cyclodextrin in the aqueous phase. Model predictions were compared with experimental results of capric acid (HA) transport across a silicone polymer membrane in the presence and in the absence of 2-hydroxypropyl-β-cyclodextrin (HPB) in the aqueous phase over wide ranges of conditions. Key parameters entering into the physical model calculations were the HA-HPB and the A(-)-HPB binding constants, the unionized and ionized free and the complexed HA species diffusion coefficients, the HA pKa, the HA intrinsic silicone polymer membrane permeability coefficient, and the aqueous boundary layer thickness. All of these key parameters were determined from independent or essentially independent experiments. The agreement between the model predictions and the experiments were generally quite good over the entire ranges of the studied independent variables. The results of this study provide an approach that is useful in the mechanistic understanding of how cyclodextrins may enhance the passive absorption of highly lipophilic, low solubility drug molecules in the intestinal tract.

Block Copolymer Vesicle Permeability Measured by Osmotic Swelling and Shrinking

Vesicle response to osmotic shock provides insight into membrane permeability, a highly relevant value for applications ranging from nanoreactor experimentation to drug delivery. The osmotic shock approach has been employed extensively to elucidate the properties of phospholipid vesicles (liposomes) and of varieties of polymer vesicles (polymersomes). This study seeks to compare the membrane response for two varieties of polymersomes, a comb-type siloxane surfactant, poly(dimethylsiloxane)-g-poly(ethylene oxide) (PDMS-g-PEO), and a diblock copolymer, polybutadiene-b-poly(ethylene oxide) (PBut-b-PEO). Despite similar molecular weights and the same hydrophilic block (PEO), the two copolymers possess different hydrophobic blocks (PBut and PDMS) and corresponding glass transition temperatures (-31 and -123 °C, respectively). Dramatic variations in membrane response are observed during exposure to osmotic pressure differences, and values for polymer membrane permeability to water are extracted. We propose an explanation for the observed phenomena based on the respective properties of the PBut-b-PEO and PDMS-g-PEO membranes in terms of cohesion, thickness, and fluidity.

A Device for Characterizing Water Vapor Permeability of Polymer Membranes

The ability of polymer membranes to transport moisture vapor plays a major role in the applications of waterproof breathable clothing materials. There is a couple of test methods available for measuring water vapor permeability of polymer membranes or laminated fabrics. They are either time-consuming or require large samples. A new test device was developed for determining the water vapor permeability of polymer membranes. It utilizes PTFE film and potassium acetate to generate a moisture permeation cup. Saturated nitrogen gas was used to yield a water vapor source. This test method offers short test time and calls for small sample size. The test results from the new method correlated well with those obtained from the ASTM E96-BW method. The subsequent measurements indicated that the water vapor diffusion resistance of one layer of microporous PTFE membrane was approximately 4.4 s/m and that the moisture vapor transport behavior of the PTFE membrane did not change as a function of water content in the membrane.

A new test method for determining water vapor transport properties of polymer membranes

The water vapor transport properties of polymer membranes are critical in applications of waterproof breathable clothing materials. Several test methods are available for measuring the permeability of polymer membrane or laminates but they are either time-consuming or require large amounts of sample. A new test apparatus was devised for determining the water vapor permeability of polymer materials. A cylinder covered with waterproof but vapor-permeable PTFE film was used to form a water vapor source. Dry nitrogen gas was utilized to carry the penetrated vapor away. This new apparatus offers a short test duration (5 min) and small sample size. The subsequent measurements showed that the water vapor diffusion resistance of one layer of microporous PTFE membrane was 5.2 s/m. Additionally, the water vapor transport behavior of the PTFE membrane does not depend upon the water content in the polymer.

The unsteady-state measurement of polymer membrane permeability to dissolved oxygen

A theoretical analysis is presented on the unsteady-state measurement of polymer membrane permeability to dissolved oxygen by means of an analyzer fitted with an oxygen electrode. The main conclusions of this analysis are as follows: (i) the oxygen mass balance must take into account the rate of oxygen consumption at the electrode; (ii) the apparent permeability coefficient Q can be derived by the unsteady-state technique provided that the quasi-steady-state condition is fulfilled for the gas transport in the membrane phase; (iii) the true permeability coefficient P can be evaluated by a set of experiments performed on a single polymeric film using the apparent permeability Q obtained at various rates of stirring.

Water Movement Through Lipid Bilayers, Pores, and Plasma Membranes: Theory and Reality. Distinguished Lecture Series of the Society of General Physiologists, Volume 4.Alan Finkelstein

Previous articleNext article No AccessNew Biological BooksWater Movement Through Lipid Bilayers, Pores, and Plasma Membranes: Theory and Reality. Distinguished Lecture Series of the Society of General Physiologists, Volume 4. Alan Finkelstein Stuart McLaughlinStuart McLaughlin Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 63, Number 1Mar., 1988 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/415748 Views: 7Total views on this site Citations: 1Citations are reported from Crossref Copyright 1988 Stony Brook Foundation, Inc.PDF download Crossref reports the following articles citing this article:Won Kyu Kim, Sebastian Milster, Rafael Roa, Matej Kanduč, Joachim Dzubiella Permeability of Polymer Membranes beyond Linear Response, Macromolecules 55, no.1616 (Jun 2022): 7327–7339.https://doi.org/10.1021/acs.macromol.2c00605