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  • 1
    Electronic Resource
    Electronic Resource
    An automated spring balance for kinetic gravimetric sorption of gases and vapors in polymers (1998)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 2510-2513 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method for automation of a McBain-type spring balance using a charge coupled device camera, a computer equipped with a frame-grabber card, and National Institutes of Health Image software is presented. This balance is used to study the sorption and transport of small molecules in polymeric materials. Kinetic gravimetric sorption data of acetone uptake in a random copolymer of 50 wt % poly(ethylene terephthalate) and 50 wt % poly(ethylene 2,6-naphthalate) at 35 °C are provided to illustrate the utility of the method. The diffusion coefficients determined from the cathetometer and camera experiments are 1.1±0.2×10−12 and 1.0±0.2×10−12 cm2/s, respectively. At an acetone partial pressure of 5.4 cm Hg, the equilibrium acetone uptake was 1.47±0.15 g acetone/100 g polymer using the cathetometer to determine spring extension and 1.52±0.15 g acetone/100 g polymer when the camera was used to determine mass uptake of acetone by the polymer. The camera-based balance was determined to be sensitive to weight changes as small as ±1 μg. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148456
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis, physical characterization, and acetone sorption kinetics in random copolymers of poly(ethylene terephthalate) and poly(ethylene 2,6-naphthalate) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2981-3000 
    Details
    ISSN: 0887-6266
    Keywords: sorption ; diffusion ; acetone ; poly(ethylene terephthalate) ; poly(ethylene 2,6-naphthalate) ; copolymers ; positron annihilation lifetime spectroscopy ; infrared spectroscopy ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Random copolymers of poly(ethylene terephthalate) (PET) and poly(ethylene 2,6-naphthalate) (PEN) were synthesized by melt condensation. In a series of thin, solvent cast films of varying PEN content, acetone diffusivity and solubility were determined at 35°C and an acetone pressure of 5.4 cm Hg. The kinetics of acetone sorption in the copolymer films are well described by a Fickian model. Both solubility and diffusivity decrease with increasing PEN content. The acetone diffusion coefficient decreases 93% from PET to PET/85PEN, a copolymer in which 85 weight percent of the dimethyl terephthalate in PET has been replace by dimethyl naphthalate 2,6-dicarboxylate. The acetone solubility coefficient in the amorphous regions of the polymer decreases by approximately a factor of two over the same composition range. The glass/rubber transition temperatures of these materials rise monotonically with increasing PEN content. Copolymers containing 20 to 80 wt % PEN are amorphous. Samples with 〈20% or 〉80% PEN contain measurable levels of crystallinity. Estimated fractional free volume in the amorphous regions of these samples is lower in the copolymers than in either of the homopolymers. Relative free volume as probed by positron annihilation lifetime spectroscopy (PALS) decreases systematically with increasing PEN content. Acetone diffusion coefficients correlate well with PALS results. Infrared spectroscopy suggests an increase in the fraction of ethylene glycol units in the trans conformation in the amorphous phase as the concentration of PEN in the copolymer increases. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2981-3000, 1998
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Gas permeability of radel a polysulfone (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 891-893 
    Details
    ISSN: 0887-6266
    Keywords: gas permeability ; structure-property correlation ; polysulfone ; Radel A ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090310718
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  • 4
    Electronic Resource
    Electronic Resource
    Long-term permeation properties of poly(1-trimethylsilyl-1-propyne) membranes in hydrocarbon - Vapor environment (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1483-1490 
    Details
    ISSN: 0887-6266
    Keywords: poly(1-trimethylsilyl-1-propyne) ; physical aging ; hydrocarbon vapors ; mixed gas permeation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(1-trimethylsilyl-1-propyne) (PTMSP), a high free-volume glassy di-substituted polyacetylene, has the highest gas permeabilities of all known polymers. The high gas permeabilities in PTMSP result from its very high excess free volume and connectivity of free volume elements. Permeability coefficients of permanent gases in PTMSP decrease dramatically over time due to loss of excess free volume. The effects of aging on gas permeability and selectivity of PTMSP membranes continuously exposed to a 2 mol % n-butane/98 mol % hydrogen mixture over a period of 47 days are reported. The permeation properties of PTMSP membranes are quite stable when the polymer is continuously exposed to a gas mixture containing a highly sorbing organic vapor such af n-butane. The n-butane/hydrogen selectivity was essentially constant for the 47-day test period at a value of 29, or 88% of the initial value of the as-cast film of 33. Condensable gases such as n-butane may serve as a “filler” in the nonequilibrium free volume of the polymer, thereby preserving the high level of excess free volume. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1483-1490, 1997
    Additional Material: 8 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hydrocarbon/hydrogen mixed gas permeation in poly(1-trimethylsilyl-1-propyne) (PTMSP), poly(1-phenyl-1-propyne) (PPP), and PTMSP/PPP blends (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2613-2621 
    Details
    ISSN: 0887-6266
    Keywords: poly(1-trimethylsilyl-1-propyne) ; poly(1-phenyl-1-propyne) ; blends ; hydrocarbons ; hydrogen ; mixed gas transport ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The gas permeation properties of poly(1-trimethylsilyl-1-propyne) (PTMSP), poly(1-phenyl-1-propyne) (PPP), and blends of PTMSP and PPP have been determined with hydrocarbon/hydrogen mixtures. For a glassy polymer, PTMSP has unusual gas permeation properties which result from its very high free volume. Transport in PPP is similar to that observed in conventional, low-free-volume glassy polymers. In experiments with n-butane/hydrogen gas mixtures, PTMSP and PTMSP/PPP blend membranes were more permeable to n-butane than to hydrogen. PPP, on the other hand, was more permeable to hydrogen than to n-butane. As the PTMSP composition in the blend increased from 0 to 100%, n-butane permeability increased by a factor of 2600, and n-butane/hydrogen selectivity increased from 0.4 to 24. Thus, both hydrocarbon permeability and hydrocarbon/hydrogen selectivity increase with the PTMSP content in the blend. The selectivities measured with gas mixtures were markedly higher than selectivities calculated from the corresponding ratio of pure gas permeabilities. The difference between mixed gas and pure gas selectivity becomes more pronounced as the PTMSP content in the blend increases. The mixed gas selectivities are higher than pure gas selectivities because the hydrogen permeability in the mixture is much lower than the pure hydrogen permeability. For example, the hydrogen permeability in PTMSP decreased by a factor of 20 as the relative propane pressure (p/psat) in propane/hydrogen mixtures increased from 0 to 0.8. This marked reduction in permanent gas permeability in the presence of a more condensable hydrocarbon component is reminiscent of blocking of permanent gas transport in microporous materials by preferential sorption of the condensable component in the pores. The permeability of PTMSP to a five-component hydrocarbon/hydrogen mixture, similar to that found in refinery waste gas, was determined and compared with published permeation results for a 6-Å microporous carbon membrane. PTMSP exhibited lower selectivities than those of the carbon membrane, but permeability coefficients in PTMSP were nearly three orders of magnitude higher. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Polymer characterization and gas permeability of poly(1-trimethylsilyl-1-propyne) [PTMSP], poly(1-phenyl-1-propyne) [PPP], and PTMSP/PPP blends (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2209-2222 
    Details
    ISSN: 0887-6266
    Keywords: poly(1-trimethylsilyl-1-propyne) ; poly(1-phenyl-1-propyne) ; blends ; gas and vapor transport ; NMR ; Maxwell model ; Bruggeman model ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Pure gas and hydrocarbon vapor transport properties of blends of two glassy, polyacetylene-based polymers, poly(1-trimethylsilyl-1-propyne) [PTMSP] and poly(1-phenyl-1-propyne) [PPP], have been determined. Solid-state CP/MAS NMR proton rotating frame relaxation times were determined in the pure polymers and the blends. NMR studies show that PTMSP and PPP form strongly phase-separated blends. The permeabilities of the pure polymers and each blend were determined with hydrogen, nitrogen, oxygen, carbon dioxide, and n-butane. PTMSP exhibits unusual gas and vapor transport properties which result from its extremely high free volume. PTMSP is more permeable to large organic vapors, such as n-butane, than to small, permanent gases, such as hydrogen. PPP exhibits gas permeation characteristics of conventional low free volume glassy polymers; PPP is more permeable to hydrogen than to n-butane. In PTMSP/PPP blends, both n-butane permeability and n-butane/hydrogen selectivity increase as the PTMSP content of the blends increases. © 1996 John Wiley & Sons, Inc.
    Additional Material: 16 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Pure hydrocarbon sorption properties of poly(1-trimethylsilyl-1-propyne) (PTMSP), poly(1-phenyl-1-propyne) (PPP), and PTMSP/PPP blends (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 1925-1934 
    Details
    ISSN: 0887-6266
    Keywords: poly(1-trimethylsilyl-1-propyne) ; poly(1-phenyl-1-propyne) ; blends ; sorption ; hydrocarbons ; sorption models ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Propane and n-butane sorption in blends of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(1-phenyl-1-propyne) (PPP) have been determined. Solubilities of propane and n-butane increased as the PTMSP content in the blends increased. This result is consistent with the higher free volume of PTMSP-rich blends and the better thermodynamic compatibility between PTMSP and these hydrocarbons. Propane and n-butane sorption isotherms were well described by the dual-mode model for sorption in glassy polymers. PTMSP/PPP blends are strongly phase-separated, heterogeneous materials. A noninteracting domain model developed for sorption in phase-separated glassy polymer blends suggests that sorption in the Henry's law regions (i.e., the equilibrium, dense phase of the blends) is consistent with the model. However, Langmuir capacity parameters in the blends are lower than predicted from the domain model, suggesting that the amount of nonequilibrium excess free volume associated with the Langmuir sites depends on blend composition. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and thermal transitions of a soluble, main chain, nematic liquid crystalline polymer exhibiting a kinetically trapped, disordered structure (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 1347-1361 
    Details
    ISSN: 0887-6266
    Keywords: liquid crystalline polymer ; nematic ; isotropic/nematic transition ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An aromatic copolyester composed of 25 mol % phenyl hydroquinone, 10 mol % isophthalic acid, 40 mol % chloroterephthalic acid, and 25 mol % t-butyl hydroquinone (PICT) has been synthesized. This amorphous, glassy polymer is soluble in common organic solvents such as methylene chloride. Thin, solution-cast films may be prepared which are in a metastable, vitrified, optically isotropic state. On first heating of an isotropic film at 20°C/min in a calorimeter, one glass transition is observed at low temperature (approximately 49°C) and is ascribed to the glass/rubber transition of the metastable, isotropic polymer. This thermal event is followed by a small exotherm due to the development of order during the scan, which results in a second Tg at approximately 125°C. This Tg is associated with the glass/rubber transition of the ordered polymer. Nematic order can be developed by thermal annealing. The lower Tg increases toward the upper Tg as annealing time is increased. For an initially isotropic film annealed at 90°C, the increase of the lower Tg with annealing time and the increase in birefringence observed by optical microscopy are governed by similar kinetics. Isotropization occurs in the temperature range of 250-300°C. The nematic polymer is slightly more dense than its isotropic analog. No detectable differences between isotropic and nematic samples were observed in rotating frame proton spin lattice relaxation times. © 1996 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Pure and mixed gas acetone/nitrogen permeation properties of polydimethylsiloxane [PDMS] (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 289-301 
    Details
    ISSN: 0887-6266
    Keywords: polydimethylsiloxane ; permeability ; sorption ; mixed gas permeation ; clustering ; acetone/nitrogen separation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The permeability of polydimethylsiloxane [PDMS] to acetone, nitrogen, and acetone/nitrogen mixtures has been determined at 28°C. In pure gas experiments, the permeability of PDMS to nitrogen was 245 × 10-10 cm3(STP) · cm/cm2 · s · cmHg and was independent of pressure. The permeability of PDMS to acetone vapor increased exponentially with increasing acetone pressure. PDMS is much more permeable to acetone than to nitrogen; acetone/nitrogen selectivity increases from 85 to 185 as acetone partial pressure in the feed increases from 0 to 67% of saturation. In mixed gas permeation experiments, the nitrogen permeability coefficient is independent of acetone relative pressure and is equal to the pure gas permeability coefficient. The acetone permeability coefficient has the same value in both mixed gas and pure acetone permeation experiments. Average acetone diffusivity in PDMS, determined as the ratio of permeability to solubility, decreases with increasing acetone concentration due to mild clustering of acetone in the polymer (because acetone is a poor solvent for PDMS) and changes in the polymer-penetrant thermodynamic interactions which influence diffusion coefficients. A Zimm-Lundberg analysis of the acetone sorption isotherm is also consistent with acetone clustering in PDMS. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 289-301, 1998
    Additional Material: 12 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    The influence of chain configuration and, in turn, chain packing on the sorption and transport properties of poly(tert-butyl acetylene) (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 49 (1993), S. 2065-2074 
    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 series of poly(tert-butyl acetylene) (PTBA) polymers was prepared with cis contents, as characterized by 13C NMR spectroscopy, ranging from 44% to 100%. The sorption and transport properties of propane in this systematically varied series were determined by a sensitive gravimetric sorption technique. As the cis content of the polymer increased, propane solubility and diffusivity decreased markedly and the d-spacing, determined by wide angle x-ray diffraction spectroscopy, decreased monotonically with increasing cis content, suggesting that higher order molecular structure, related explicitly to configurational variations, may strongly influence chain packing in these rigid, glassy materials and, in turn, sorption and transport properties of small molecules in this polymer series. © 1993 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070491202
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