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  • 1
    Electronic Resource
    Electronic Resource
    Diffusion as a probe to assess stretching-induced morphological changes in polyurethane (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1083-1087 
    Details
    ISSN: 0887-6266
    Keywords: polyurethane ; diffusion ; wide-angle x-ray diffraction ; phase mixing ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An analysis of the diffusion of toluene through polyurethane based on bis (p-cyclohexyl diisocyanate), poly(tetramethylene glycol) 1000, and 1,4-butane diol, subjected to varied degrees of elongation by stretching, is presented. The diffusion coefficient is increased by 60% in polymers drawn to 200% and above. Beyond 400% elongation, the diffusion coefficient attained a constant value. Associated changes are observed in the wide-angle x-ray diffraction pattern. These diffusion and x-ray changes are correlated with restructuring of the polymer induced by stretching. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090310903
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  • 2
    Electronic Resource
    Electronic Resource
    Permeation and sorption in polynorbornenes with organosilicon substituents (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1273-1283 
    Details
    ISSN: 0887-6266
    Keywords: polynorbornenes ; permeation ; diffusion ; sorption ; plasticization ; spin probes ; free volume ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Gas sorption properties, permeability coefficients, and diffusion coefficients of a series of norbornene polymers are presented. Introduction of the Si(CH3)3 group into the polynorbornene (PNB) backbone chain results in significant increases in glass transition temperature, permeability, and diffusion coefficient for a number of gases (H2, O2, N2, CO2, CH4, C2H6). The transport properties and sorption isotherms for poly(5-trimethylsilyl norbornene) (PTMSNB) are very similar to those for poly(vinyltrimethyl silane) (PVTMS), which contains the same side-chain group but differs from PTMSNB by the structure of its main chain. For another silicon-containing polymer poly[5-(1,1,3,3-tetramethyl-1,3-disilabutyl) norbornene] (PDSNB) having a bulkier side-chain group, the glass-transition temperature is decreased in comparison with that of PNB, presumably owing to self-plasticization. Both silicon-containing norbornene polymers (PTMSNB and PDSNB) have permeability coefficients for “rapid” gases like H2 or CO2 of about 102 Barrer. The high values of the Langmuir sorption capacity C′H for PTMSNB and PVTMS, as well as the high diffusivity and mobility of spin probes in these polymers, were attributed to a large free volume related to the bulky Si(CH3)3 groups attached directly to the main chain. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090311002
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  • 3
    Electronic Resource
    Electronic Resource
    Gas sorption and diffusion in hydrogen-bonded polymers. II. Polyethersulfone/polyhydroxyether blends (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 131-139 
    Details
    ISSN: 0887-6266
    Keywords: hydrogen bond ; gas sorption ; gas transport ; gas permeability ; diffusion ; polymer blends ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The gas sorption behavior of CO2, C2H6, and CH4, and the gas transport behavior of CO2 and CH4, were examined for polyethersulfone (PES), polyhydroxyether, and four miscible blends containing 20, 40, 60, and 80 wt % PES. The 40 wt % PES blend exhibited the lowest sorption levels and the lowest permeabilities for all of the gases. Application of the dual-mode sorption model revealed negative deviations for the Henry's law parameter kD that were larger than those observed for blends relying on van der Waals or simple polar interactions. Also, the magnitude of the blend interaction parameter obtained from the gas sorption data and the volume of mixing were both more negative in the hydrogen-bonded blend. Diffusion coefficients at infinite dilution and from the dual mode/partial immobilization model exhibited minima at 40 wt % PES, as did the fractional free volume, a measure of chain packing ability. © 1994 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090320116
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  • 4
    Electronic Resource
    Electronic Resource
    Higher order hydrodynamic interactions in the calculation of polymer transport properties (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1785-1797 
    Details
    ISSN: 0887-6266
    Keywords: diffusion ; hydrodynamics ; transport properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Higher order hydrodynamics interactions are short-range modifications to the Oseen tensor Tij and its self-interaction counterpart Tii. They differ from the Oseen tensor in having terms of higher order than the first in a/R, a being a bead radius and R being a bead-bead distance. Effects of higher order hydrodynamic interactions on whole chain-whole chain hydrodynamic interactions are here computed. Higher order hydrodynamic interactions are shown to lead to a concentration dependence of the diffusion and friction coefficients of a free monomer. However, while higher order interactions make contributions of the same nature to the drag coefficients of a monomer and of a whole chain, the contributions are not simply multiplicative, removing a justification for the common practice of correcting polymer solution transport data for “monomer friction effects” via a normalization with data on friction coefficients of free monomers. © 1993 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090311212
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  • 5
    Electronic Resource
    Electronic Resource
    Interdiffusion of PMMA and PVF2, studied by solid-state NMR (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 785-789 
    Details
    ISSN: 0887-6266
    Keywords: PMMA ; PVF2 ; diffusion ; solid-state NMR ; cross-depolarization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A previously published new solid-state nuclear magnetic resonance (NMR) method is applied to the interdiffusion of poly(methacrylate) (PMMA) and poly(vinylidene fluoride) (PVF2) above their Tg. Via a variation of the cross-polarization technique magnetization is transferred from protons to fluorines. When this magnetization is made to disappear at the fluorine sites, only those protons that are distant from fluorines greater than the distance over which cross-polarization functions will retain their magnetization. In this way we detect the fraction of PMMA near (ca. 20 Å) PVF2. Starting from sheets of PMMA and PVF2, which are then heated at 190°C for a variable time, and applying the above technique, we can determine the fractions of PMMA and PVF2 that have diffused within a distance of a few Å of each other. The intrinsic diffusion coefficients of PMMA and PVF2 determined from such experiments compare well with literature data. Initial attempts to fit the experimental data suggest that the concentration dependence of the diffusion coefficients cannot be neglected. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090320501
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  • 6
    Electronic Resource
    Electronic Resource
    Gas transport properties of polymers based on spirobiindane bisphenol (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 487-494 
    Details
    ISSN: 0887-6266
    Keywords: gas separations ; diffusion ; gas sorption ; spirobiindane bisphenol ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Transport properties of pure gases in polycarbonates, polyesters, and polyetherimides based on 6,6′-dihydroxy-3,3,3′,3′-tetramethyl-1,1′-spiro biindane (SBI) and bisphenol-A (BPA) are compared at 35°C. The SBI monomer contains two spiro-linked five-membered rings which are fused to the phenyl rings at the meta and para positions to the hydroxyl groups. This molecular structure gives SBI-based polymers with higher fractional free volume (FFV) and lower intramolecular motions as compared to the BPA-based analogs. The inhibition of chain packing due to the SBI moiety yields polymers with much higher permeabilities for all the gases studied, despite the hinderance of mobility associated with the SBI structure. Simultaneous increase in selectivity was also observed for some gas pairs. Oxygen permeabilities up to 5.9-fold higher with increases of up to 13% in O2/N2 selectivities were observed for a polyester based on SBI as compared to its analog based on BPA. Higher permeabilities of up to 4.3-fold for He and up to 4.8-fold for CO2 were observed due to the substitution of SBI for BPA. Not surprisingly, lower values of He/CH4 and CO2/CH4 selectivities were obtained for the more open SBI-containing polymers. The changes in fractional free volume and inhibition of small-scale mobility for some materials caused by the SBI moiety were measured and used in the interpretation of the gas transport properties. The individual contributions of diffusivity and solubility to the overall transport behavior of the polymers are discussed and correlated to the structural alterations caused by the SBI substitution for BPA monomer. © 1995 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330317
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  • 7
    Electronic Resource
    Electronic Resource
    Comments on a model for mass transfer during phase inversion (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 2175-2179 
    Details
    ISSN: 0887-6266
    Keywords: phase inversion ; modeling ; diffusion ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090331509
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  • 8
    Electronic Resource
    Electronic Resource
    Sorption and diffusion of carbon dioxide in single-phase polystyrene/poly(vinylmethylether) blends (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2723-2730 
    Details
    ISSN: 0887-6266
    Keywords: polystyrene ; poly(vinylmethylether) ; blends ; carbon dioxide ; sorption ; diffusion ; plasticization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The sorption and transport properties of CO2 in miscible PS/PVME blends at 20°C are reported as a function of pressure from 1 to 15 atm. The complex shape of isotherms for glassy blends and the concentration-dependent diffusion coefficient for rubbery blends reveal a plasticization by sorbed CO2. The significant depression in Tg has to be taken into account in the analysis of the sorption data. Diffusion coefficient for CO2 passes through a minimum when plotted against the blend composition. Such a behavior can be quantitatively related to the negative volume mixing of the PS/PVME system in the framework of the theories based on unoccupied volume. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Dual-mode free volume model for diffusion of gas molecules in glassy polymers (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1737-1746 
    Details
    ISSN: 0887-6266
    Keywords: free volume ; dual mode ; diffusion ; glassy polymer ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The development of a new model for the diffusion of gas molecules in glassy polymers is presented which utilizes concepts from free volume theory and relies on a dual-mode interpretation of sorptive dilation in glassy polymers. Three assumptions are made in the development of the model. First, the free volume available for molecular transport processes is taken as constant below the glass transition temperature. Second, two populations of gas molecules are assumed to exist - one which contributes to the maintenance of an iso-free volume state upon sorptive dilation and one which does not contribute owing to sorption into regions of unrelaxed volume. Third, the former population is assumed to be mobile while the latter is not. The resulting model predicts, at constant temperature, a diffusion coefficient that is independent of solute volume fraction. This is in contrast to the widely used dual-mode sorption model with partial immobilization for gas transport in glassy polymers which leads to a diffusion coefficient that is dependent on solute mole fraction through the molar gas concentration. The new model is used to interpret gas transport data from permeation experiments for carbon dioxide, methane, and ethylene in three polycarbonates. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1737-1746, 1997
    Additional Material: 9 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Diffusion of methyl ethyl ketone in polyisobutylene: Comparison of spectroscopic and gravimetric techniques (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1261-1267 
    Details
    ISSN: 0887-6266
    Keywords: FTIR-ATR spectroscopy ; gravimetric sorption ; diffusion ; polymer ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In this study, vapor sorption FTIR-ATR (Fourier Transform Infrared Attenuated Total Reflectance) spectroscopy was combined with a conventional gravimetric sorption balance to examine diffusion in polymers. Mutual diffusion coefficients of methyl ethyl ketone in polyisobutylene were measured using both methods at various penetrant activities and temperatures in the range 40-60°C. Actual penetrant concentrations were determined from the sorption balance. The diffusion coefficients from the two techniques agree very well with each other. In addition, the diffusivity data from both techniques could be correlated successfully as a function of temperature and concentration with the Vrentas and Duda free-volume model. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1261-1267, 1997
    Additional Material: 7 Ill.
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