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  • 1985-1989  (14)
  • Polymer and Materials Science  (13)
  • Chemical Engineering
  • 1
    Electronic Resource
    Electronic Resource
    Zur statistik des einbaus einer als regler in polyamid 12 verwendeten aliphatischen dicarbonsäureHerrn Prof. Dr. Dr. h. c. H. Hellmann zum 75. Geburtstag gewidmet. (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 169 (1989), S. 193-209 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: As hard blocks in polyether block amides, polyamides are used whose length is intensively regulated by dicarboxylic acids. Since, with regard to melting and crystallization behaviour, this acid constitutes an interfering structural unit in the chain, and in the case of a completely converted product each chain contains one acid molecule, it is essential to know where in the chain incorporation will occur. As opposed to monofunctional chain regulators which always form a chain end, a bifunctional chain regulator can a priori also be randomly incorporated into the inner part of the chain. This leads to a far greater interference than occurs if the chain regulator molecule and the chain end, which acts as an interfering unit in any case, coincide with each other.By means of adipic acid-regulated oligoamides based on lauryl lactam, the incorporation of the chain regulator was examined by NMR spectroscopy and compared with model calculations. This resulted in a close match only if it was presupposed that the incorporation was carried out randomly with the same degree of probability at any point whatsoever between two lauryl lactam structural units or at the chain end.Further calculations illustrate the effects of the incorporation of the chain regulator on the size of the amorphous portion.
    Notes: Als Hartblöcke in Polyetherblockamiden werden durch Dicarbonsäuren stark geregelte Polyamide eingesetzt. Da die Säure in Hinblick auf das Schmelz- und Kristallisationsverhalten einen Störbaustein in der Kette darstellt und bei einem ausgeregelten Produkt jede Kette ein Säuremolekül enthält, ist es von Bedeutung zu wissen, wo in der Kette der Einbau erfolgt. Anders als bei monofunktionellen Reglern, wo der Regler stets ein Kettenende bildet, kann ein bifunktioneller Regler a priori auch statistisch im Inneren der Kette eingebaut werden. Dies führt zu einer viel stärkeren Störung, als wenn das Reglermolekül und das sowieso als Störstelle wirkende Kettenende zusammenfallen. Anhand adipinsäuregeregelter Oligoamide auf Basis von Laurinlactam wird kernresonanzspektroskopisch der Einbau des Reglers untersucht und mit Rechnungen verglichen. Es ergibt sich nur dann gute Übereinstimmung, wenn vorausgesetzt wird, daß der Einbau statistisch erfolgt und dabei mit gleicher Wahrscheinlichkeit für jede beliebige Stelle zwischen zwei Laurinlactambausteinen oder am Kettenende abläuft. Weitere Rechnungen verdeutlichen den Einfluß des Reglereinbaus auf die Größe des amorphen Anteils.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051690118
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  • 2
    Electronic Resource
    Electronic Resource
    Etude de nouvelles membranes asymétriques à base de copolymère à blocs styrène-isoprène-styrène, 1. Synthèse, modification chimique et caractérisation (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 559-571 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A styrene-isoprene-styrene block copolymer was selected for the preparation of new asymmetric membranes which have blood compatibility properties after chemical modification by addition of gazeous N-chlorosulfonyl isocyanate to the double bonds of the polyisoprene sequences. The membranes were examined with a scanning electron microscope. The permeability of the membrane was studied as a function of time, pressure and viscosity.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860311
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  • 3
    Electronic Resource
    Electronic Resource
    Silicium-29 kern-relaxations-messungen an kieselsäurederivaten (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 887-898 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Derivatives of silicic acid of the type Si6O5R18 and Si8O7R18 (R = Cl, OCH3, and OC2H5) as well as bicyclic Si8O9(OC2H5)14 were isolated and characterized by 29Si NMR. The spin-lattice-relaxation and the nuclear Overhauser enhancement factor of the esters were determined between 273 and 343 K. The temperature dependency of the dipolar contribution to the longitudinal relaxation time gave an energy of activation for the segmental motion of the siloxane skeleton of about 10 kJ/mol which is independent of the kind of building unit.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880422
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  • 4
    Electronic Resource
    Electronic Resource
    Morphologie der segmentierten polyetheresteramide auf der basis von polyamid 12 und oligotetrahydrofuranHerrn Prof. H.-J. Cantow zum 65. Geburtstag gewidmetVorgetragen anläßlich des Makromolekularen Kolloquiums in Freiburg, 1986. (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 2053-2065 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyetheresteramides (PEEA) on the basis of polyamide 12 and oligotetrahydrofuran (OTHF) may be referred to as intrinsically plasticized and intrinsically impact strength toughened thermoplastic elastomers. This is due to their special 4-phase morphology consisting of two pure crystalline and two mixed amorphous phases, which was completely analysed by various TEM preparation techniques. PEEA containing more than 50% PA 12 hard segments exhibit a space filling dendritic superstructure of lamellar crystallized hard segments. In the range of 50 - 30% PA 12, the dendrites become more and more isolated, and below 30% PA 12 only single lamellae can be observed. The matrix in all PEEA is an amorphous, PA 12-rich mixed phase (“OTHF-plasticized PA 12”) located between the hard segment lamellae. An amorphous OTHF-rich mixed phase is very finely dispersed in PEEA and acts as an intrinsically impact strength toughening modifier. Lamellar crystallized soft segments could be imaged by TEM in this dispersed phase, but only in PEEA products with a higher molecular OTHF and at sufficient low temperatures.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890908
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of crosslink density and internetwork grafting on the transparency of polyurethane/polystyrene interpenetrating polymer networks (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 1467-1473 
    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: Because of their incompatibility and the different refractive indices of the homopolymer components, polyurethane/polystyrene interpenetrating polymer networks are turbid by nature. Different parameters likely to enhance their transparency are examined: the crosslink density of each network and the level of internetwork grafting. The results prove that the latter factor is the most effective, as in some cases, very clear and transparent samples are obtained. Correspondingly, preliminary investigations of the dynamic mechanical properties show an inward shift of the glass transition temperatures for such systems. It is concluded that parameters able to cause a higher degree of phase dispersion can yield transparent materials.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070360616
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  • 6
    Electronic Resource
    Electronic Resource
    Using vapor pressure information in a cubic equation of state (1987)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 33 (1987), S. 503-505 
    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: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690330318
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  • 7
    Electronic Resource
    Electronic Resource
    Polymers with a high refractive index and low optical dispersion (1989)
    Weinheim : Wiley-Blackwell
    Advanced Materials 1 (1989), S. 294-295 
    Details
    ISSN: 0935-9648
    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: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19890010809
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  • 8
    Electronic Resource
    Electronic Resource
    High performance alloys for solving severe corrosion problems in flue gas desulfurization systemsLecture held at the ACHEMA '88, Frankfurt, June 5 to 11. (1989)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 40 (1989), S. 409-417 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Einsatz von Hochleistungswerkstoffen bei extremen Korrosionsbedingungen in RauchgasentschwefelungsanlagenNickellegierungen werden kostengünstig dann eingesetzt, wenn in den Abgasreinigungsanlagen von mit Kohle gefeuerten Kraftwerken extreme Korrosionsbedingungen vorliegen. Die wirtschaftlichen Vorteile werden aufgezeigt und praktische Anworten auf Korrosionsprobleme gegeben. Hierbei wird besonderer Nachdruck auf die metallische Auskleidung von Behältern nach dem sogenannten “Wallpaper-Konzept” gelegt. Der Aufsatz zählt eine große Anzahl von Fällen auf, in denen sich HASTELLOY-Legierungen beim Einsatz in Rauchgasentschwefelungsanlagen erfolgreich bewährt haben. Weiterhin werden weiterentwickelte Nickellegierungen im Hinblick auf ihre Anwendung für Komponenten solcher Anlagen besprochen.Innerhalb der Gruppe der Ni-Cr-Mo-W-Legierungen zeigt die Legierung C-22™ die beste Beständigkeit gegen Loch- und Spaltkorrosion in halogenhaltigen Medien (chlorid-/fluoridhaltige Lösungen).H-9M™ ist die derzeit neueste Legierung in der Reihe der Ni-Cr-Mo-Fe-Legierungen. Ihre Loch- und Spaltkorrosionsbeständigkeit ist eindeutig der von Werkstoff 625 überlegen. H-9M ist in einer Reihe von Rauchgasentschwefelungsanlagen im Vergleich mit anderen Werkstoffen geprüft worden und befindet sich derzeit in der Form von Anlagenbauteilen im praktischen Einsatz. Die eisenhaltige Legierung bietet darüber hinaus durch ihren günstigen Preis einen besonderen Anreiz.
    Notes: Nickel-base alloys have been used as cost-effective measures in a variety of severely corrosive situations in pollution control units for coal-fired power plants. Cost-effectiveness and practical answers to corrosion problems are illustrated (specifically the “wallpaper concept”/metallic lining technique). Numerous cases of successful use of HASTELLOY® alloys in Flue Gas Desulfurization (FGD) system are listed. New developments in nickel-base alloys and their use in FGD components are discussed.In the Ni-Cr-Mo-W alloy family, C-22™ alloy has the best resistance to localized corrosion in halide environments (chlorides/fluorides-containing solutions).The H-9M™ alloy is the latest development in the Ni-Cr-Mo-Fe alloy family. This alloy has shown superior performance in its resistance to localized corrosion, compared to alloy 625. H-9M alloy has been tested in several FGD systems and placed in field service. This iron-containing alloy is an attractive candidate due to its moderate cost.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19890400702
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  • 9
    Electronic Resource
    Electronic Resource
    Prediction of protein-ligand interactions: The complex of porcine pancreatic elastase with a valine-derived benzoxazinone (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1207-1225 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Prior to availability of the crystal structure of the complex, we evaluated models of the complex between porcine pancreatic elastase and a t-Boc-Val-derived benzoxazinone inhibitor. Models of the noncovalent and covalent complex were generated using computer graphics and each model was subjected to energy minimization using molecular mechanics. After the crystal structure became available, we found that the model with the lowest energy was in good agreement with the crystal structure, except for the position of the His57 side chain. Permissible conformations of the inhibitor were based on information from x-ray crystal structures and an earlier conformational energy investigation of t-Boc-amino acids. We did not, however, limit ourselves to these conformations. The conformation of the inhibitor in the lowest energy model and crystal structure, was not similar to any of the minimum-energy conformations of t-Boc-amino acids. This suggests that limiting proposed binding modes only to the lowest energy conformations of a ligand (prior to binding) may sometimes unfairly bias the procedure.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260802
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  • 10
    Electronic Resource
    Electronic Resource
    Ethanol-Herstellung mit Bakterien (1987)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 59 (1987), S. 695-700 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ethanol production with bacteria. Strains of Saccharomyces cerevisiae have mostly been used for the production of ethanol from sugar by yeasts. Recently it was shown that the bacterium Zymomonas mobilis has some advantages compared to yeast for the production of industrial alcohol. Compared to traditional yeast fermentation, ethanol yield is about 5% higher than with yeast, since less sugar is incorporated into cell material by this bacterium. Like yeast, Zymomonas mobilis has remarkably high ethanol tolerance which enables the bacterium to produce ethanol concentrations of more than 13 vol.-% from sugar solutions of appropriate concentration. Investigations of the spectrum of lipids present have shown that this bacterium contains large quantities of hopanoids which are presumably of significance for the stabilization of cell membranes in the presence of ethanol. Since the cost of the sugar greatly influences the profitability fraction formed in the production of glucose syrup from wheat flour was investigated. It was shown that after enzymatic saccharification of this waste starch the glucose was efficiently fermented to ethanol by Zymomonas mobilis. It is planned to broaden the substrate spectrum of Zymomonas mobilis by gene cloning techniques so that in future pentoses, e. g. xylose or arabinose, can also be fermented to ethanol by this organism.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330590904
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