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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of azo-containing polydimethylsiloxanes and their copolymers with methyl methacrylate (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2613-2620 
    Details
    ISSN: 0887-624X
    Keywords: polydimethylsiloxane ; poly(methyl methacrylate) ; block copolymer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Azo group-containing polydimethylsiloxanes (PDMS-ACP), macroazoinitiators, were prepared by polycondensation reaction of 4,4′-azobis-4-cyanopentanoyl chloride (ACPC) with hydroxybutyl-terminated polydimethylsiloxane (PDMS) of varying molecular weights. The activation energy (Ea), activation enthalpy (ΔH
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Wrong-way behavior of packed-bed reactors: Influence of interphase transport (1989)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 1148-1156 
    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: Large transient temperature excursions may be caused by a sudden reduction in the feed temperature to a packed-bed reactor operating at an intermediate conversion. When a unique steady state exists for all feed temperatures, the magnitude of the wrong-way behavior predicted by a two-phase model is very close to that predicted by a pseudohomogeneous model if PeH is equal to the dimensionless heat transfer coefficient H. The two-phase model enables a more efficient numerical simulation in such cases. The predictions of these two models may be rather different when steady-state multiplicity exists for some feed temperatures. In such cases, a two-phase model, which accounts for the axial dispersion of heat, should be used to simulate the transient behavior. The wrong-way behavior may lead to an ignition of a low-temperature state or an upstream propagation of a transient temperature wave.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690350710
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  • 3
    Electronic Resource
    Electronic Resource
    Experimental investigation of the polymer melt flow during injection post-filling process (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2661-2663 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690411217
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  • 4
    Electronic Resource
    Electronic Resource
    Wrong-way behavior of packed-bed reactors: II. Impact of thermal dispersion (1988)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 34 (1988), S. 1663-1672 
    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 sudden reduction in the feed temperature of a packed-bed reactor may lead to a transient temperature rise, referred to as a wrong-way behavior. As expected, the axial dispersion of heat decreases the magnitude of the temperature excursion and prolongs the transient shift to a new steady state. In addition, the thermal dispersion may enable the wrong-way behavior to ignite a low-temperature steady state leading to a disastrous runaway of the reactor. Moreover, it may create a transient high-temperature wave, which moves initially in the upstream direction. The axial dispersion of heat can lead to some behavioral features which are qualitatively different from those of a model which ignores it. The transient temperature excursion does not exceed a value, which can be estimated by a simple analytical expression.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690341010
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of carboxylated poly(butyl acrylate) latices produced by a semibatch process (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 585-594 
    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: Several carboxylated poly(butyl acrylate) latices prepared by a semibatch emulsion poly-merization process were characterized in this study. A significant amount of polyelectrolyte was found in the latex product containing 10% AA, designated as AA10. On the other hand, latices containing 0.1% AA (AA0.1), 0.1% MAA (MAAC.1), and 10% MAA (MAA10) showed very low levels of polyelectrolyte in water. Based on the critical flocculation concentration data, it can be concluded that incorporation of 10% AA or 10% MAA into the emulsion polymers can greatly improve the chemical stability of the latex products, especially at higher pH. The data of the pH and conductometric titration experiments show that the MAA unit can be distributed more uniformly in the latex particles in comparision with the AA unit. This result is further confirmed by determination of the Tg's of the emulsion polymers by means of thermally stimulated current (TSC). © 1996 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Nylon 4/PVA blend membrane for dialysis (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 1795-1804 
    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: To improve the hydrophilicity and enhance the transport flux of nylon 4 membrane for dialysis, this study attempts to utilize blending nylon 4 with poly(vinyl alcohol) (PVA). The instability of PVA in water can be obtained more easily than by other methods, such as chemical, γ-ray irradiated crosslinking, or high-temperature treatment used by previous researchers. The effects of maturation time of the casting solution, nylon 4/PVA ratios, and casting solvent compositions on esterification of PVA, salt permeability, water content, partition coefficient, diffusivity, and mechanical strength of membrances are studied. The membrane, prepared by casting solution of nylon 4/PVA = 9/1 wt % formic acid with 24-h maturation time, possesses permeabilities of NaCl and urea, 33.14 and 19.67 × 10-5 cm2/min, respectively.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070431003
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  • 7
    Electronic Resource
    Electronic Resource
    Role of surfactant in composite latex particle morphology (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 487-499 
    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: Composite particles were prepared by seeded emulsion polymerization at 70°C using K2S2O8 as initiator and two different nonionic surfactants. Monodisperse polystyrene latex particles were used as seed and methyl methacrylate was used as second-stage monomer. When the surfactant, polyethylene oxide-propylene oxide (Pluronic F-108), was used, the final particle morphology showed that the PMMA (core) was partially covered by polystyrene. However, when nonyphenol polyethylene oxide (Igepal Co-990) was used as surfactant, one observed a reversed type of encapsulation (i.e., PS core is partially engulfed by PMMA). The interfacial tensions of the polymer phase against water containing the appropriate surfactant were measured by the drop-volume method and used in a mathematical model based on thermodynamic analysis to predict the equilibrium particle morphology. The observed particle morphologies were found to differ from the predicted morphologies at low conversion of the second-stage monomer but agreed with it at higher conversion.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450313
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  • 8
    Electronic Resource
    Electronic Resource
    Enzymatische Baeyer-Villiger-Oxidationen durch flavinabhängige Monooxygenasen (1988)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 100 (1988), S. 342-352 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Seit einiger Zeit findet die Biochemie der Mikroorganismen wieder verstärktes Interesse. Dies beruht nicht zuletzt auf der Tatsache, daß ständig mehr unnatürliche organische Substanzen in die Biosphäre gelangen und deshalb Mikroorganismen zum Abbau dieser Xenobiotica gesucht werden. Weiterhin haben Fortschritte auf dem Gebiet der Gentechnologie neue Möglichkeiten eröffnet, die „chemische Fabrik“ der Bakterien zu nutzen. Durch die Baeyer-Villiger-Reaktion können relativ einfach Ketone in Ester oder Lactone umgewandelt werden; die Reaktion ist für die organische Synthese äußerst nützlich. Jedoch läßt die Ausbeute zu wünschen übrig, und hin und wieder sind drastische Reaktionsbedingungen nötig. Es gibt nun Bakterien, die in Medien mit aliphatischen Verbindungen leben können und Enzyme besitzen, die Baeyer-Villiger-Reaktionen katalysieren. Diese Enzyme, sogenannte Monooxygenasen, sind am Abbau acyclischer und alicyclischer Ketone zu einfacheren Verbindungen beteiligt. Bemerkenswert ist die Vielzahl von Reaktionen, die von einigen dieser Enzyme katalysiert wird. Aufgrund dieser Mannigfaltigkeit und der Zugänglichkeit von reinen Enzymen mit Hilfe der Gentechnologie erhöhen sich die Chancen, diese Biokatalysatoren als Reagentien für die organische Synthese nutzen zu können.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19881000305
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  • 9
    Electronic Resource
    Electronic Resource
    Enzymic Baeyer-Villiger Oxidations by Flavin-Dependent Monooxygenases (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 333-343 
    Details
    ISSN: 0570-0833
    Keywords: Baeyer-Villiger oxidation ; Monooxygenases ; Enzyme catalysis ; Oxidation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: There has recently been a revival of interest in microbial biochemistry. Part of this resurgence is due to the increased presence of man-made organic compounds in the biosphere and the resultant interest in microorganisms which can degrade these xenobiotic molecules. Also, advances in genetic engineering have raised the possibility of utilizing the chemical machinery of bacteria for commercial profit and social benefit. The Baeyer-Villiger reaction is a useful transformation in organic synthesis which provides chemists with a gentle means of converting ketones into esters or lactones. The reaction, however, suffers from the problems of low yield and the need, in some cases, to utilize harsh conditions. There exist bacteria, capable of growth on aliphatic molecules, that contain enzymes which can catalyze Baeyer-Villiger reactions. These enzymes, known as monooxygenases, are involved in the breakdown of acyclic and alicyclic ketones to provide simpler carbon units for further catabolism. The gamut of reactions catalyzed by some of these enzymes is remarkable. This diversity, plus their availability in pure form in quantity by genetic engineering raises the possibility that these biocatalysts can be useful as reagents in organic synthesis.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.198803331
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