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  • 1
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 12 (1991), S. 436-446 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A continuously monitored single-filament composite (CM-SFC) test was conducted to measure the stress at which successive fiber breaks occur in the single fiber fragmentation process. This exercise was performed with a limited number of samples of various types. The purpose was to explore the possibility of using this test as a simple alternative means of (i) measuring the size effect in single fibers, (ii) calculating the Weibull shape and scale parameters for fiber strength, (iii) calculating the fiber/matrix interfacial shear strength from the extrapolated value of fiber strength using the loading history of a single fragmentation test, rather than from the value of fiber strength extrapolated from extensive testing of single fibers at various gage lengths, as is usually done. These are aspects of the SFC test that have largely been ignored so far. The results presented here confirm the possibility of using the CM-SFC test for such purposes, with a certain degree of approximation, as discussed. Additional information supplied by this test as well as a possible effect of fiber pre-tensioning on fragmentation results (including the value of the interfacial shear strength) are also briefly discussed.
    Additional Material: 6 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 115-118 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The combination of pyrolysis and field ionization (Fl) mass spectrometry is used to characterize and identify mucous polysaccharides isolated from plant material (crude drugs). Oven pyrolysis is simply performed inside the ion source using a commercial direct introduction system. About 20μg of sample is thermally degraded by heating linearly from 50°C to 600°C at a rate of 0.4°C s-1.The thermal evaporation profiles and FI mass spectra of the pyrolysates of five pharmaceutically used plant mucilages were recorded and found to differ significantly from one another. The mass spectra show almost exclusively peaks corresponding to molecular ions of pyrolysis products which are characteristic for polysaccharides and demonstrate the presence of aldohexoses, aldopentoses and deoxyhexoses. The ratios of the characteristic signals of the dehydration products of these three groups of sugar subunits give semiquantitative information on the composition of these polysaccharides. The relative abundances of the key signals were compared with quantitative data obtained by classical methods, e.g. gas chromatography, and found to be a useful, indicative value.Comparison of the FI spectra of the mucilage pyrolysates with spectra of reference samples of mono- and oligosaccharides allows the identification of subunits in the sugar polymers. This is supported by the occurrence of their typical pyrolysis products which were assigned in previous pyrolysis studies.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 3315-3328 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymeric methacrylates functionalized with free methacryloyl groups are efficiently crosslinked in the presence of transition-metal carbonyls on UV irradiation of the polymeric solid. The reaction proceeds by a radical chain mechanism with a kinetic chain length of about 10 in a solvent-free polymer containing 10-3 mole of methacryloyl groups per cm3. The chain length increases steeply when the glass transition of the polymer is reached, either by plastification or by an increase in temperature. The temperature dependence of the crosslinking yield below the glass transition is consistent with an activation energy of about 9 kcal mole-1. The addition of acrylic monomers enhances chain propagation by up to an order of magnitude. Postirradiative crosslinking in the matrix comes to a standstill well before all acrylic groups or radicals have been exhausted: if, after cessation of the primary reaction, the matrix is briefly heated, a second crop of crosslinks is obtained without further exposure. The system behaves thus as if the radicals had been removed into traps from which they can be set free by thermal activation. From an analysis of the reaction kinetics it appears that in the glassy polymer 90% of the radicals are inactivated in this way. Radical recombination, however, is the principal mechanism of chain termination above the glass transition. From the kinetic data, diffusion coefficients for polymer-bound groups are found to be in the range of 10-17-10-16 cm2 sec-1 in the glassy polymer at room temperature. They are of the order of 10-14 cm2 sec-1 in plasticized films above the glass transition.
    Additional Material: 8 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 12 (1991), S. 233-236 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper demonstrates the usefulness of careful experimental work with model composite materials, such as thin polymeric films in which single fibers are accurately positioned, in at least two respects: to assess the validity of a theory for a given physical property, and to accurately probe the effects of various parameters on the behavior of composites. Working with such model composites has obvious advantages, such as the full control of experimental parameters, the possibility of introducing perturbative effects in a controlled way, and the possibility of verifying theoretical models in the range of low fiber content. Indeed, macroscopic composite materials contain various types of defects and perturbative effects, such as fiber misalignment or slack, fiber-poor regions, voids, etc., which bias any quantitative assessment of mechanical and physical properties, and preclude the accurate verification of theoretical schemes. One difficulty in working with microcomposite models, also recalled here, is the need for an appropriate “scaling-up” procedure to the level of macroscopic composites.
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 65 (1993), S. 1078-1078 
    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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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 65 (1993), S. 1050-1051 
    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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  • 7
    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
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 71 (1999), S. 950-950 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    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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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 71 (1999), S. 952-953 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    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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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 41 (1969), S. 1100-1105 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Zur Klärung des Zeitverhaltens einer Füllkörperkolonne bei der Rektifikation eines ternären Systems wurden sprungförmige Störungen im Flüssigkeits/Dampf-Verhältnis vorgenommen. Die Kolonne bestand aus einem Verstärkerteil und wurde kontinuierlich betrieben. Als Testgemisch diente das nahezu ideale System Äthylacetat/Benzol/Trichloräthylen. Die Zeitkonstanten, die das Abklingen der Störungen charakterisieren, wurden gemessen sowie Übergangsfunktionen und Konzentrationsprofile beschrieben.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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