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  • Polymer and Materials Science  (58)
  • gas separations  (2)
  • membrane  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Dimethyl acetamide sorption equilibria in a urethane/urea/ether block copolymer (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 1991-1998 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A study of the interaction of solvent in a urethane/urea/ether copolymer belonging to the spandex family of materials is presented. Sorption and desorption isotherm data for N,N-dimethylacetamide (DMAc) in spandex solutions are used to determine thermodynamic parameters of solvent/polymer interaction. Isosteric enthalpies for sorption of DMAc tend to approach the heat of evaporation of DMAc at high sorbed concentrations. A qualitative mechanism for assemblage of hard-segment domains in the polymer during desorption is presented and interpreted in terms of the sorption isotherms and isosteric enthalpy data. The study provides useful insights into the influence of particulate additives, such as titanium dioxide (TiO2) in the solution.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070431105
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  • 2
    Electronic Resource
    Electronic Resource
    Permeation of several gases through elastomers, with emphasis on the deuterium/hydrogen pair (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 1033-1046 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The diffusion and permeation coefficients for He, H2, D2, O2, and N2 in a variety of elastomers were measured by simple manometric methods. The elastomers studied were butyl rubber; Hypalon® 40 and 45; Viton® E60 and GF; Hydrin® 100 and filled Hydrin® 100; Kraton® G, FG, and KG VTEOS; EPDM; epoxidized natural rubber; and neoprene. Consistent with earlier studies, elastomers with higher glass transition temperatures exhibited lower diffusion coefficients. The ratio of diffusion coefficients of the hydrogen isotope pair differed from the purely molecular-weight-based prediction. Deuterium's slightly smaller size relative to hydrogen is consistent with observed deviations from the molecular-weight-based diffusion coefficient ratio. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070470610
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation of polymer-ceramic composite membranes with thin defect-free separating layers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1927-1938 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer - ceramic composite membranes with essentially defect-free separating layers have been prepared by a solution deposition technique. Rigid polymers were used for the selective organic layer. These included high molecular weight samples of 5,5′-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis-1,3-isobenzofuran-dione, isopropylidenedianiline (6FDA-IPDA), 5,5′-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis-1,3-isobenzofuran-dione, methylenedianiline (6FDA-MDA), tetramethylhexafluorobisphenol-A polycarbonate (TMHFPC), and tetramethylhexafluoropolysulfone (TMHFPSF). Attempts to prepare composite membranes from lower molecular weight samples of bisphenol-A polycarbonate (PC) and tetrabromohexafluorobisphenol-A polycarbonate (TBHFPC) were unsuccessful. The PC and TBHFPC composites exhibited a decrease in the measured gas flux after polymer deposition; however, the selectivities of the composites were considerably less than that of a dense film of the same materials. A microporous ceramic membrane prepared by Anotec Separations was used as the support layer. This ceramic membrane provided minimal resistance to gas flow. The selective composite membranes were found to have high gas fluxes and gas separating abilities essentially equivalent to that of a dense isotropic film. The estimated, effective skin layer thicknesses for these membranes are on the order of 1500 Å to 1.0 μm. The formation of these composites is believed to occur through a sieving process in which large swollen polymer chains are sieved out of solution by the ceramic support. Polymer solutions that had swollen coil diameters that were smaller than that of the ceramic membrane did not produce selective composite membranes, while those solutions with swollen coil diameter that were larger than that of the ceramic membrane produced defect-free polymer layers. © 1992 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070461105
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  • 4
    Electronic Resource
    Electronic Resource
    Gas-separation applications of miscible blends of isomeric polyimides (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 1059-1064 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of polyimide isomers containing hexafluoroisopropylidene in the central moiety of the diamine residue have been studied. The isomers differed by having either a meta or a para linkage between the diamine and dianhydride residues. The miscibility of these materials was investigated by studying the glass transition temperature behavior using differential scanning calorimetry. Mixtures of isomer pairs, such as 6FDA-6FmDA and 6FDA-6FpDA, exhibited one glass transition temperature. Tg, and were therefore miscible. Mixtures of nonisomer pairs exhibited two Tg's and were immiscible. The gas sorption and transport properties of the blends of the 6FDA-6FmDA and 6FDA-6FpDA isomers were characterized for a variety of gases at 35°C for pressures up to 60 atm. The permeabilities and permselectivities in the miscible blends fell between those of the pure components and were approximately logarithmic averages of the pure component properties. The miscibility of the polyimide isomers enables one to tailor the composition of the material to optimize the gas separation and mechanical properties. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070500614
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  • 5
    Electronic Resource
    Electronic Resource
    Dimethylacetamide sorption kinetics in a urethane/urea/ether block copolymer (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 1685-1699 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer solvent interactions in a block polyurethane/urea/ether polymer belonging to the spandex family are considered in this article. Independent analysis of the sorption isotherms for dimethylacetamide (DMAc) in the spandex spandex polymer as a function of vapor activity and temperature were presented in a previous article. A second aspect in understanding solvent/polymer interactions is the kinetics of desorption. Characterization of the solvent devolatilization is an important aspect of the drying procedure to guide processing protocols to eliminate residual solvent in the final spandex products, especially for medical applications [E. Hicks, A. Ultee, and J. Drougas, Science, 147, 373 (1965); J. W. Boretos and W. S. Pierce, J. Biomed. Mater. Res., 2, 121 (1968); P. M. Knight and D. J. Lyman, J. Membr. Sci., 17, 245 (1984)]. This article reports data for desorption kinetics under nominally isothermal conditions to provide diffusion coefficients as a function of polymer phase concentration and temperature. Desorption curves were found to be Fickian at least up to the half-time of desorption. Diffusion coefficients were therefore calculated using a half-time method. Temperature effects upon sorption or desorption were measured to obtain corrected diffusion coefficients and found to be singificantly different than the apparent diffusion coefficient measured from a conventional McBain sorption cell. © 1994 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070511001
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  • 6
    Electronic Resource
    Electronic Resource
    Sorption of CO2/CH4 mixtures in poly(phenylene oxide) and a carboxylated derivative (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 2613-2626 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The sorption of CO2 and CH4 and their binary mixtures in poly(phenlene oxide) (PPO) and its carboxylated derivative (CPPO) is reported. All mixed gas data are accurately described by the dual model sorption model, which predicts mixed gas sorption on the basis of pure gas sorption parameters. The present paper extends the mixed gas sorption data base to include polymers having a wide range of permeabilities and chemical structures. The confirmed accuracy of the model for these systems provides strong support for applying the mixed gas dual mode sorption model to any gas/polymer system. A numerical simulation of the mixed gas sorption experiment is also presented which greatly simplifies the experimental procedures used to maintain the partial pressure of one of the gas components at a constant value over the course of a sorption isotherm measurement. By establishing the appropriate amounts of each gas component which are added to the polymer sample chamber of the sorption cell, the mixed gas apparatus simulator (MIGAS) can be used to maintain the partial pressure of one of the components to within 1% of the desired value.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420926
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  • 7
    Electronic Resource
    Electronic Resource
    Selective permeation of hydrocarbon gases in poly(tetrafluoroethylene) and poly(fluoroethylene-propylene) copolymer (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 1755-1774 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The permeabilities and diffusivities of methane, ethane, propane, n-butane, and isobutane in commercially available poly(tetrafluoroethylene) (TFE) and poly(fluoroethylene-propylene) (FEP) Teflon have been measured in a Pasternak-type permeation cell. Experiments were carried out at upstream hydrocarbon partial pressures up to 50 torr (1000-60,000 ppm gas phase concentration) and temperatures from 40 to 195°C with films of 0.0508 and 0.127 mm thickness using nitrogen as carrier gas on the upstream and downstream sides of the membrane. The transient and steady-state permeation data are described well by a combination of Henry's law and Fick's law with a concentration-independent diffusion coefficient. Linear Arrhenius plots of both permeabilities and diffusivities were obtained. Linear correlations were found both between the activation energy for diffusion and the square of the gas molecule diameter, and between the logarithm of solubility at 90°C and the penetrant boiling point. Separation factors for binary mixtures of hydrocarbons were measured for TFE at 140°C and found to be similar to those predicted by individual permeabilities in most cases. Measurements with mixed gases were not made for FEP Teflon, but selectivities of FEP are expected to be similarly well described by the ratios of the pure gas permeabilities at the low partial pressures studied. The effect of annealing FEP Teflon for 24 hr at 200°C was found to produce an average of 20-30% reduction in solubility as well as a 9% increase in the activation energy for diffusion compared to as-received films. These effects are believed to be due to increased crystallinity in the sample upon annealing.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1980.070250822
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  • 8
    Electronic Resource
    Electronic Resource
    Sorption and transport of benzene in poly(ethylene terephthalate) (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 1095-1110 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetics and equilibria of benzene sorption in poly(ethylene terephthalate) were measured at 40°C, 50°C, and 60°C, with benzene activities ranging from 0.02 to 0.3. At most experimental conditions, diffusion was found to be Fickian; however, evidence of non-Fickian transport was found at the highest activity levels. Values of the diffusion coefficient of benzene range from 10-14 cm2/s at 40°C to 10-12 cm2/s at 60°C in the limit of low concentrations. Nonlinear isotherms observed for benzene sorption were successfully interpreted in terms of the dual mode model for sorption in glassy polymers, whereby the sorbed penetrant exists as two populations: one sorbed according to Henry's law and the other following a Langmuir isotherm. Non-Fickian transport data were correlated with a model that superimposes diffusion of both the Henry's law and Langmuir populations (the “partial immobilization” model) upon first-order relaxation of the polymer matrix.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070290407
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  • 9
    Electronic Resource
    Electronic Resource
    Gas transport in halogen-containing aromatic polycarbonates (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 1977-1986 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The gas permeability and permselectivity of a series of halogen-containing polycarbonates are discussed in terms of the fundamental solubility and diffusivity factors. These materials have structural features that hinder interchain packing and intrachain rotational mobility. Both diffusion and solubility coefficients are higher in materials with higher fractional free volumes. Diffusivity selectivities tend to increase with increasing restriction of intrachain torsional mobility. The materials with four bromine atoms substituted on the phenyl rings ortho to the carbonate linkages display a significantly increased diffusivity selectivity relative to conventional polycarbonate. This improvement in the ability of the polymer matrix to discriminate between gas molecules of different sizes is due to a reduction in intrachain torsional mobility. The reduction in chain mobility is indicated by higher glass transition and higher sub-Tg transition temperatures in the bromine-substituted materials. The materials with hexafluoroisopropylidene moieties have high fractional free volumes and exhibit a very significant increase in permeability relative to conventional bisphenol-A polycarbonate. The material with both the hexafluoro and the tetrabromo substitutions displays significant simultaneous increases in permeability and permselectivity relative to conventional polycarbonate.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070431103
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  • 10
    Electronic Resource
    Electronic Resource
    Gas transport through integral-asymmetric membranes: A comparison to isotropic film transport properties (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 48 (1993), S. 2161-2171 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Pressure-normalized gas fluxes for defect-free integral-asymmetric membranes prepared according to a dry/wet phase inversion process were measured as a function of temperature and pressure and compared to measurements on thick isotropic films. Asymmetric membranes were prepared from polysulfone, polycarbonate, and poly(ester carbonate). The activation energies of permeation for O2 and N2 in the range of 25-55°C were higher for the asymmetric polysulfone membranes than for a thick isotropic film. O2/N2 selectivities of the asymmetric membranes are higher than those for isotropic films. The asymmetric membranes did not show the typical dualmode behavior for the CO2 flux as a function of pressure as determined for thick films. Differences in the free volume and its distribution in the ultrathin skin layer of the asymmetric membranes compared to isotropic films may be responsible for these results. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070481210
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