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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 1 (1990), S. 143-150 
    ISSN: 1042-7147
    Keywords: Reinforcement ; Amorphous ; Matrix ; LC-polyester ; 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
    Notes: The preparation and the mechanical properties of binary blends of amorphous thermoplastics and a para-linked liquid crystalline polyester, which is expected to act as a reinforcement, are reported. The LC-polyester has the advantage that it is soluble in common organic solvents, that it has a low transition temperature, and that it does not crystallize readily. Polycarbonate, polystyrene, poly(methyl methacrylate), and poly(ether sulfone) were selected as matrix materials. Most of the films cast from the blends turned out to be turbid and thus phase separated, the sizes of the dispersed phases ranging between 0.2 μm (in polycarbonate) and 1 μm (in polystyrene).The LC-polyester causes a substantial increase of the stiffness in blends with polycarbonate, poly(methyl methacrylate), and poly(ether sulfone) and almost no increase in the case of polystyrene. These differences are attributed to the particular magnitudes of the strength of the phase coupling between the matrix and the dispersed phase, which is controlled by their compatibility.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 2 (1993), S. 87-92 
    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The machining of several materials such as polymers, metals and ceramics using excimer lasers (193, 248 and 308 nm) was investigated. By photoablation, micrometer resolution can be achieved for polymers if the wavelength and fluence are chosen properly. High-definition processing of metals is complicated by the occurrence of surface melting. An interaction between the ablation plume and the walls of the laser-drilled holes leads to hole widening in the case of polymers at high fluences. For small structures (〈100 μm) all materials investigated show a size-dependent ablation rate. This effect has to be taken into account if a precise ablation depth is required for a pattern with structures of different sizes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 7 (1997), S. 123-133 
    ISSN: 1057-9257
    Keywords: nanocomposites ; sol-gel ; heteropolymetallates ; photochromics ; holographic data storage ; amplitude grating ; two-wave-mixing recording ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: This paper describes the properties of some new organic-inorganic photochromic layers. They are based on a hybrid organic-inorganic matrix in which tungsten heteropolyoxometallates (SiW12O4-40, PW12O3-40) are entrapped in a network obtained from the reaction of 3-glycidoxy-propyltrimethoxysilane. The high homogeneity of these materials on the nanoscale leads to transparent monoliths and layers of controlled thicknesses up to 40 μm. The optical properties of the blend are emphasised and the construction of amplitude gratings in the materials by two-wave-mixing experiments is described. The results of the optical experiments and the comparison with the theoretical background are used as a model for photochromic holographic storage processes. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 543-552 
    ISSN: 1040-0397
    Keywords: Chronopotentiometry ; Enzyme electrode ; Biosensors ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chronopotentiometry (CP) with enzyme electrodes is a new approach to overcome inherent problems of steady-state potentiometric processes. The developed procedure is presented on the example of a glucose oxidase (GOD) electrode. Electrochemically generated mediator helps to overcome traditional difficulties arising from poorly defined mixed potentials in the presence of oxygen during an analysis. Transition times are automatically evaluated by using computerized calculation programs. The technique can be used for determining substrate concentrations; moreover, it is particularly promising as an effective tool to study electrode processes with biochemical systems on an electrode surface.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 1040-0397
    Keywords: Biosensors ; Self-assembly monolayers ; NADH ; Phenoxazines ; Phenothiazines ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Self-assembled monolayers of cystamine and cysteine chemisorbed on gold electrode surfaces have been used as a support for covalent immobilization of some phenoxazine and phenothiazine derivatives. The covalent attachment was achieved after previous functionalization of the free amino groups on the electrode surface with bifunctional reagents (terephthaloyl chloride and 1,6-hexamethylene diisocyanate) able to react with the imino form of the amino group in position 3 of the phenoxazine and phenothiazine derivatives.In every case, a shift of the redox potentials between 130 and 180 mV towards more positive potentials, as well as an increase in the peak-topeak separation between anodic and cathodic peaks was observed after covalent attachment. The surface coverages (10-11 〈 Γ 〈 10-10 mol/cm2) obtained from the cyclic voltammograms were those for a not densely packed monolayer and varied depending on the redox compound immobilized. The surface-modified electrodes obtained were afterwards used for the electrocatalytic oxidation of NADH.UV-vis spectroscopy was used to monitor the successive steps of surface modification using gold semitransparent electrodes. The total surface coverage of redox mediator on the electrode surface could also be calculated from the optical difference spectra between the oxidized and the reduced state obtained ‘in situ’ in a spectroelectrochemical cell.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 67 (1995), S. 1157-1157 
    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
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 34 (1983), S. 328-331 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 2,2′-azo-bis-isobutyronitrile was completely thermally decomposed in allyl benzene. The reaction mixture obtained was separated by preparative gas and thin-layer chromatography. Using steam pressure measurements and the logarithmic dependence of gas chromatographic retention value of the molecular weight the molecular weight of the separated components was investigated. The structure was analysed by IR- and NMR-spectroscopy and 14C-labelled tracer substances. A mechanism of the reactions is discussed.
    Notes: 2,2′-Azo-bis-isobutyronitril wurde in Allylbenzen thermisch vollständig zersetzt. Das entstehende Reaktionsgemisch konnte mit Hilfe der präparativen Gas- und Dünnschichtchromatographie getrennt werden. Die Bestimmung der Molmassen der abgetrennten Komponenten erfolgte über Dampfdruckmessungen sowie über die logarithmische Abhängigkeit der gaschromatographischen Retentionswerte von den Molmassen. Die Konstitutions- und Konfigurationsaufklärung gelang mittels IR- und NMR-Spektroskopie sowie durch Anwendung von 14C-markierten Tracer-Substanzen. Ein möglicher Reaktionsablauf wird diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 18
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The constants derived for the copolymerization systems of allylbenzene, 2-methylpentene-1 and isobutene with acryloninitrile, the rAN values being independent of the comonomer mixture and the yield, as well as the parameters rANL required for estimating the effect of the solvent by combining the overall rate and copolymerization equations were found to correlate linearly with the donor value of the solvent. The effect of the solvent is explained predominantly by the interaction of electrophilic macroradicals being solvated to different degree with acrylonitrile at the chain end.
    Notes: Die für die Copolymerisationssysteme von Allylbenzen, 2-Methylpenten-1 und Isobuten mit Acrylnitril abgeleiteten Konstanten, die von der Comonomermischung und dem Umsatz unabhängigen rAN-Werte sowie die zur Quantifizierung des Lösungsmitteleinflusses aus der Kombination von Bruttogeschwindigeits- und Copolymerisationsgleichung erhaltenen Parameter rANL korrelieren linear mit der Donorzahl der Lösungsmittel. Der Lösungsmitteleinfluß wird vor allem durch die Wechselwirkung des unterschiedlich solvatisierten elektrophilen Makroradikals mit Acrylnitril am Kettenende erklärt.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 19
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The r-values of the monomer pair acrylonitrile/allylbenzene in the radical bulk and solution polymerization, using hexamethylphosphoric acid triamide, dimethylsulfoxide, γ-butyrolactone, ethylene carbonate and nitromethane as solvents, have been determind. A copolymerization equation is derived, considering the degradative chain transfer, associate formation and solvent effect, by which the deviations from the Mayo-Lewis concept and the solvent effects can be explained.
    Notes: Die r-Werte des Monomerpaares Acrylnitril/Allylbenzol wurden bei der radikalischen Copolymerisation in Substanz bzw. in den Lösungsmitteln Hexamethylphosphorsäuretriamid, Dimethylsulfoxid, γ-Butyrolacton, Ethylencarbonat und Nitromethan bestimmt. Unter Berücksichtigung der degradativen Kettenübertragung, der Assoziatbildung und des Lösungsmitteleinflusses wurde eine Copolymerisationsgleichung abgeleitet, mit deren Hilfe die Abweichung vom Mayo-Lewis-Modell und Lösungsmitteleffekte interpretierbar sind.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 20
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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