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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of liquid chromatography with nonuniform crystallite particles (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 1569-1576 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical analysis for the pulse responses of a liquid chromatographic column packed with crystal powders having a particle size distribution and a nonlinear adsorption isotherm is presented. The mathematical model is solved numerically by the orthogonal collocation method. Based on the parametric analysis of the model, the effects of a symmetrical and moderately asymmetric PSD on the LC responses are shown to be negligible in comparison with the effects of other parameters, such as isotherm nonlinearity, whose effects are much more profound. The simulated responses are compared with the experimental response data for an LC column packed with silicalite crystals, and a good agreement is found between the theoretical and experimental results. Using the nonlinear LC model, the simultaneous determination of nonlinear adsorption isotherms and intraparticle diffusivities from LC pulse responses is demonstrated for liquids in porous adsorbents.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690361013
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  • 2
    Electronic Resource
    Electronic Resource
    CVD of solid oxides in porous substrates for ceramic membrane modification (1992)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 445-454 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The deposition of yttria-doped zirconia has been experimented systematically in various types of porous ceramic substrates by a modified chemical vapor deposition (CVD) process operating in an opposing reactant geometry using water vapor and corresponding metal chloride vapors as reactants. The effects of substrate pore dimension and structure, bulk-phase reactant concentration, reactant diffusivity in substrate pores and deposition temperature are experimentally studied and explained qualitatively by a theoretical modeling analysis. The experimental and theoretical results suggest a reaction mechanism which depends on water vapor and chloride vapor concentrations. Consequently, the diffusivity, bulk-phase reactant concentration, and substrate pore dimension are important in the CVD process. Effects of deposition temperature on the deposition results and narrow deposition zone compared to the substrate thickness also suggest a Langmuir-Hinshelwood reaction mechanism involved in the CVD process with a very fast CVD reaction rate. Gas permeation data indicate that whether deposition of solid in substrate pores could result in the pore-size reduction depends strongly on the initial pore-size distribution of the substrate.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690380313
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  • 3
    Electronic Resource
    Electronic Resource
    Sol-gel preparation and properties of Alumina adsorbents for gas separation (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 559-570 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The sol-gel method is applied to prepare Cu+ or Ag+ containing alumina adsorbents which have potential application in purification or separation of carbon monoxide or olefins containing gases. Wet impregnation and sol-solution mixing methods are used to incorporate the active species into the sol-gel derived γ-alumina support. These alumina adsorbents have the characteristics of large specific surface area, high dispersion of active specie on the grain surface, and mesopore size with a uniform pore size distribution. The gas chromatographic technique determines the carbon monoxide adsorption properties on these alumina adsorbents. Adsorption equilibrium constants, adsorption rate constants, axial dispersion coefficients, heat of adsorption, and adsorption activation energy are determined from GC response peaks by using the moment method. The alumina adsorbents prepared by the solgel method appear to be superior to the similar adsorbents prepared by other methods.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410314
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  • 4
    Electronic Resource
    Electronic Resource
    Granulation of sol-gel-derived nanostructured alumina (1997)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 505-514 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A sol-gel granulation process was developed to prepare porous nanostructured γ-alumina granules as supports for catalysts and adsorbents. The process, which starts with an aqueous sol of gelatinous boehmite, involves droplet formation, gelation in paraffin oil, conditioning in ammonia solution, and drying and calcination in air under controlled conditions. The γ-Al2O3 granules prepared are 1-3 mm-dia. spherical particles with large surface area (380 m2/g) and pore volume (0.5 cm3/g), uniform pore-size distribution (20-60 Å), and controllable average pore size (35 Å). These sol-gelderived granules have excellent mechanical properties with crush strength (〉100 N per granule) and attrition resistance (〈0.01 wt. %/h), much better than the commercial alumina and zeolite granules. Supported CuO sorbents were prepared on these granules for SO2 removal applications. The alumina-supported CuO sorbents contain higher loading of well-dispersed CuO and better sulfation properties than similar sorbents reported in the literature.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690430223
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  • 5
    Electronic Resource
    Electronic Resource
    Viscometry and light scattering on moderately concentrated solutions of poly(vinyl chloride) (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 1981-1998 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Moderately concentrated solutions (0.015-0.10 g/mL) of poly(vinyl chloride) have been studied in three different solvents by light scattering and viscometry. It is concluded that intermolecular association occurs in all solutions studied, including data over the temperature interval 25-110°C. The data can be interpreted in terms of a model with loci of association holding chains together in an aggregate that has an overall configuration similar to that of a randomly branched polymer.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1987.090250916
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  • 6
    Electronic Resource
    Electronic Resource
    XPS and AES studies of carbon steel polarized in aqueous molybdate solutions (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 19 (1992), S. 409-413 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: X-ray photoemission spectroscopy (XPS) and Auger electron spectroscopy (AES) have been used to study the passive film on carbon steel produced electrochemically in aerated and deaerated molybdate aqueous solutions. Very few molybdate ions were adsorbed on the oxide surface of the carbon steel in aerated solution according to XPS measurements. On the contrary, significant amounts of Mo(+4), Mo(+5) and Mo(+6) ions were detected on the anodically polarized steel in deaerated solution. In addition to molybdate ions and iron oxides, MoO(OH)2 and Mo2O5 were suggested to be present in the opaque passive film.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740190176
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  • 7
    Electronic Resource
    Electronic Resource
    Processing property relationship for dicyandiamide-cured epoxy networks (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 685-691 
    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
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330229
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  • 8
    Electronic Resource
    Electronic Resource
    Epoxy network structure effect on physical aging behavior (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 4595-4605 
    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: Using dicyandiamide as curing agent, several epoxy networks are formed with different formulations and curing cycles. Both sub-Tg isothermal enthalpy relaxation and dynamic enthalpy relaxation in transition zone have been studied using differential scanning calorimetry (DSC). The isothermal enthalpy relaxation rates of all epoxy networks are quite similar and in good agreement with Arrhenius' law. Nevertheless, dynamic relaxation behaviors in the transition zone are very different. These observations are discussed in connection with relaxation mechanism and chemical structure of the networks. Evolutions of mechanical properties during sub-Tg annealing are monitored by means of three-points bending tests. The ductility of unprecured epoxy networks decreases with time; otherwise, the precured and/or filled networks present a stability with regards to mechanical properties. Explanations for these phenomena take into account a possible competition between the relaxation of residual stresses and the network structural relaxation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320424
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  • 9
    Electronic Resource
    Electronic Resource
    BDMA-catalyzed DDA-epoxy resin system: Temperature and composition effects on curing mechanism (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 2171-2184 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: DSC and IR data on benzyldimethylamine-catalyzed dicyandiamide-DGEBA prepolymer system have been utilized to investigate the influences of temperature and composition on the curing mechanism. Etherification as a competitive reaction is favored at lower temperature. On the other hand, the reaction pathway of dicyandiamide (DDA) varies with temperature, especially at the first stage of reaction. At 100°C, the reaction of DDA is shown to be essentially the substitution of the hydrogen atoms by ring-opening of epoxy groups, giving rise to N-alkyl cyanoguanidine. But at 140°C or 160°C, the initial reaction of DDA involves a transformation of nitrile groups to imine groups. A greater amount of BDMA and a higher amine-to-epoxy ratio favor the etherification. The glass transition temperature Tg is a complex function of these different mechanisms; higher Tg could be reached with a amino-to-epoxy ratio equal to 0.6 and after a curing cycle including a precure at 100°C.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240911
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  • 10
    Electronic Resource
    Electronic Resource
    Water barrier characteristics of plasma polymers of perfluorocarbons (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 1843-1851 
    Details
    ISSN: 0887-624X
    Keywords: water barrier ; plasma polymers ; surface dynamics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Perfluorocarbon monomers such as C2F4, C2F6, C4F10, and mixtures thereof with H2, were subjected to plasma polymerization and deposited onto low-density polyethylene (LDPE) substrates. The effect of plasma conditions, surface characteristics, and surface dynamics of plasma polymers on their ability to improve the resistance to water vapor permeation was investigated. An optimum discharge energy density was found for a monomer which provided the greatest reduction water vapor permeability. Although all of the plasma polymers show higher hydrophobicity than polyethylene, the reduction in water vapor permeability is not uniquely related to water contact angle. The surface-dynamic stability of a plasma polymer surface was found to be the key factor in determining the barrier performance of the plasma polymer. The extent of change of surface-configuration after water immersion strongly correlated with the improvement in the water vapor permeation resistance. Plasma polymers with the higher surface-dynamic stability provided the better water barrier coating applied on LDPE films. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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