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  • Polyurethaneionomer  (3)
  • permeability  (3)
  • Korea
  • Springer  (6)
  • American Geophysical Union (AGU)
  • 1990-1994  (6)
Collection
Keywords
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  • Springer  (6)
  • American Geophysical Union (AGU)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Aqueous dispersion of polyurethane ionomers from hexamethylene diisocyanate and trimellitic anhydride (1991)
    Springer
    Colloid & polymer science 269 (1991), S. 895-900 
    Details
    ISSN: 1435-1536
    Keywords: Polyurethaneionomer ; emulsion ; trimelliticanhydride ; particlesize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polyurethane (PU) ionomers were prepared from trimellitic anhydride (TMA), poly(tetramethylene adipate) glycol (PTAd), and hexamethylene diisocyanate (HDI) in acetone. Upon neutralizing the carboxylic groups with a tertiary amine (TEA), and adding water to PU ionomer solution, followed by removing the acetone, stable aqueous PU dispersions were obtained. Effects of interionic molecular weight and nonionic hydrophilic segment, viz. monofunctional ethylene-propylene oxide ether on particle, size, emulsion viscosity, mechanical, and viscoelastic properties of the emulsion cast films were examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00657306
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  • 2
    Electronic Resource
    Electronic Resource
    Preparations and properties of polyurethane aqueous dispersion from uncatalyzed systems of H12MDI, PTAd/bisphenol A polyol, and DMPA (1991)
    Springer
    Colloid & polymer science 269 (1991), S. 889-894 
    Details
    ISSN: 1435-1536
    Keywords: Polyurethaneionomer ; H 12MDI ; PTAd ; DMPA ; particlesize ; mechanicalproperties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Aqueous dispersions of polyrethane (PU) containing ionic and nonionic hydrophilic segments were prepared in a prepolymer mixing process using substantial amount of solvent. The acid groups were neutralized with tertiary amine, and chain extension in aqueous media was carried out with triethylene tetramine. Average particle size and particle size distribution of the dispersion, and mechanical and viscoelastic properties of the emulsion cast films were determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00657305
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  • 3
    Electronic Resource
    Electronic Resource
    A new model for impregnation mechanisms in different GF/PP commingled yarns (1994)
    Springer
    Applied composite materials 1 (1994), S. 351-371 
    Details
    ISSN: 1573-4897
    Keywords: commingled yarn ; impregnation ; consolidation ; thermoplastics ; processing ; permeability ; mechanical testing ; mathematical modelling ; compression moulding ; glass fibre bed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Impregnation mechanisms of different kinds of GF/PP commingled yarns have been studied. As the reinforcing fibres were always the same, a global description has been worked out. Two different mathematical approaches for fibre bed permeability (Kozeny-Carman and Gutowski) were compared. The constants of the applied mathematical models have to stay the same if the fibre reeinforcement and the fibre arrangement is the same. Neither the kind of matrix, nor the fibre volume content may change these constants. Differences in the degree of impregnation after the same process conditions can be only due to different sizes of fibre agglomerations, thus the initial distribution of reinforcing fibres and matrix. For an exact determination of impregnation times and conditions the exact distribution of fibres in the intermediate material and after processing has to be known. This distribution is determined by SEM microscopy and data given from the material supplier. The importance of different process parameters, such as temperature, pressure, processing time is weighted by determining the density and mechanical properties of the specimens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568041
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  • 4
    Electronic Resource
    Electronic Resource
    Studies on the mechanisms of active ion fluxes across alveolar epithelial cell monolayers (1992)
    Springer
    Methods in cell science 14 (1992), S. 187-193 
    Details
    ISSN: 1573-0603
    Keywords: transport ; epithelium ; edema ; beta-agonist ; barrier ; permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To investigate the cell physiologic and biological properties of the alveolar epithelium, we studied rat alveolar epithelial cell monolayers grown on permeable supports in primary culture. Type II alveolar epithelial cells were disaggregated using elastase, and partially purified on a discontinuous metrizamide gradient. These isolated cells were plated onto tissue culture-treated Nuclepore membrane filters at 1.5×106 cells/cm2 and maintained in a humidified incubator (5% CO2 in air, 37° C). After 2 days in culture, the bathing media on both sides of the cell monolayers were changed to fresh culture medium, thus removing nonadherent cells (mostly leukocytes). These monolayers exhibit a high transmonolayer resistance (〉2000 Ω-cm2) and actively transport ions. Radionuclide flux studies indicate that Na+ is the predominant ionic species absorbed actively under baseline conditions, accounting for about 80% of the total active ion transport. Cl− seems to be passively transported across the epithelium. However, when the epithelium is exposed to a beta-agonist (terbutaline), active absorption of Na+ is increased and active absorption of Cl− occurs. Although it is clear that both active Na+ and Cl− transport are dependent on Na+/K+-ATPase activity, and that Na+ enters cells predominantly through channels, the specific mechanisms by which Cl− enters and exits the alveolar epithelial cells remain unclear. The stimulated reabsorption of Na+ and Cl− may be important in helping to remove excess fluid from alveolar air spaces in the lung.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01409010
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  • 5
    Electronic Resource
    Electronic Resource
    Structure-property relationship of polyurethane ionomer (1992)
    Springer
    Colloid & polymer science 270 (1992), S. 956-961 
    Details
    ISSN: 1435-1536
    Keywords: Polyurethaneionomer ; DMPA ; neutralization ; mechanicalproperties ; viscoelasticproperties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polyurethane (PU) ionomers were prepared using various types of polyol (PTAd, PCL, PTMG, and PPG) and isocyanate (MDI, HDI, and IPDI), together with different extender (DMPA) contents, degree of neutralization, and number average molecular weight (M n) of polyol. Modulus (E′), strength (σb), and glass transition temperature (T g) significantly increased with the increased amount of extender and extender neutralization. Among three of the iocyanate used, PU from MDI gave the highest modulus, strength, andT g. With regard to theM n of PTAd (600, 1000, 2000), PU from PTAd 600M n gave the highest modulus, strength, andT g, due probably to the highest hard segment content and phase mixing. On the other hand, PU from PTAd 2000M n gave significantly improved strength over PTAd 1000M n, and the highest elongation. The results were interpreted in terms of soft-segment crystallization, and soft-hard phase separation, which was concluded from the lowered softT g.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00655964
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  • 6
    Electronic Resource
    Electronic Resource
    Transport of Thyrotropin Releasing Hormone in Rabbit Buccal Mucosa in Vitro (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 1113-1122 
    Details
    ISSN: 1573-904X
    Keywords: thyrotropin releasing hormone ; buccal mucosa ; metabolism ; permeability ; in vitro tissue integrity ; transport pathways ; rate-limiting barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The transport of thyrotropin releasing hormone (TRH) in rabbit buccal mucosa in vitro has been investigated with respect to (a) rate and type of metabolism of TRH on mucosal and serosal sides of buccal mucosa, (b) mechanism of TRH transport including charge effect on its permeability, and (c) pathway and rate-limiting regions of TRH movement. In addition, the integrity of excised buccal mucosa has been evaluated for purposes of in vitro solute diffusion experiments using tissue ATP level data, transmission electron microscopy, and TRH transport kinetic data. The results indicate that excised rabbit buccal mucosa can be used for TRH diffusion studies for approximately 6 hr. In addition, TRH apparently traverses buccal mucosa by simple diffusion with a steady-state permeability of about 10−7 cm/sec, and this permeability is independent of pH. Moreover, the primary pathway appears to be via the intercellular space in the rate-limiting barrier, i.e., the upper 50 µm of the epithelium. Finally, TRH is degraded predominantly by deamidase activity, which is followed by, to a lesser degree, carboxypeptidase metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015883217858
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