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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 18 (1992), S. 897-905 
    ISSN: 1573-1561
    Keywords: Pollen ; corn ; Zea mays ; teosinte ; Zea mexicana ; allelopathy ; phenylacetic acid ; phytotoxicity ; Amaranthus leucocarpus ; Echinochloa crusgalli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Phenylacetic acid (PAA), one of the phytotoxic compounds in corn (Zea mays) pollen, was identified by GC-MS and by direct comparison with a pure commercial sample of PAA. Bioassays were carried out by testing whole pollen, methylene chloride extract of the pollen, and pure PAA on germination and radical growth ofAmaranthus leucocarpus andEchinochloa crusgalli. The effect of corn pollen was compared with that ofZea mexicana (Teosinte), one of the wild relatives of cultivated maize.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 49 (1993), S. 1595-1601 
    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: This research reports on the effect of a diazide, i.e., 1.4-carboxybenzenesulfonyl diazide, which had been incorporated onto fiber by a chemical reaction, on the formation of an interphase between the elastomeric SBR matrix and polyester fiber. The existence of the interphase becomes manifest not only in the variation of the mechanical properties, but especially through swelling measurements and dynamic properties. The effect of the new system based on diazide is similar to that obtained from a conventional adhesive system, but presents certain benefits, such as a shorter curing time due to absence of resin, enhanced tensile strength, and the formation of a more flexible interphase, which entails lesser heat generation due to mechanical energy loss. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 1721-1730 
    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: The dynamic properties of composite materials consisting of an ethylene-propylene rubber matrix (EPDM) and short polyester polyethylene-terephthalate (PET) fiber vary with dynamic stress amplitude applied to the material. These variations support the statement that fiber treatment with 1,4-carboxy-sulphonyl-diazide, which acts as a bridge between the fiber and the matrix and hence enhances the strength of the interface enabling it to resist greater strain applied to the composite and, as a consequence, yielding greater retention values of the storage modulus, measured longitudinally to preferential fiber orientation, E′L. By means of transversal measurements of the storage modulus, E′T, of these materials it is possible to determine a parameter b, which eventually indicates the degree of matrix-fiber bonding and which is consistently higher for materials filled with surface-treated fiber. This enhanced phase adhesion is further confirmed by higher equivalent interfacial thickness values, ΔR, which, in addition, vary less with increasing dynamic strain amplitude. Finally dissipated energy variation or mechanical energy loss, Eloss, is studied as a function of fiber content and strain amplitude. Experimental findings show Eloss to increase with fiber content and strain amplitude, when measured at constant strain amplitude ∊0, and to yield higher values for treated fiber samples. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 2447-2454 
    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: Stress-strain and stress relaxation properties are studied in composites consisting of a thermoplastic elastomer butadiene styrene copolymer (SBS) matrix and oxidated carbon fiber. The results obtained from samples at different degrees of oxidation are contrasted with those obtained from SBS filled with commercial carbon fiber. Carbon fiber oxidation with nitric acid gives rise to an increase in functional surface groups, which in turn enhance the capacity in the fiber to interact with the matrix. In the experimental composites, the increase in fiber-matrix interactions translates into proportionally greater strain necessary to reach the yield point, as well as into an increase in stress at the yield point. In addition, at initial strain below the strain at yield point, a slower stress relaxation rate is observed in oxidated fiber composites, as compared with those recorded for the matrix filled with commercial fiber. In the oxidated fiber composites, stress relaxation occurs in three stages, the first two of which may be associated to the fiber-matrix interface. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 57 (1995), S. 831-842 
    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: The determination of viscoelastic property variation in short fiber-reinforced composites, as a function of strain, temperature, and frequency, constitutes a useful tool when the existence or the strength of matrix-fiber interfaces are to be examined. In this work, these properties are studied in thermoplastic elastomer matrix materials (SBS) filled with commercial carbon fiber (PAN), oxidated, and subsequently treated with diazide, which generates SO2N3 groups on the fiber surface, theoretically capable of chemical reaction with the polymeric chain. For the composite containing diazide-treated oxidated fiber, certain phenomena have been proven to occur, such as lesser storing modulus losses in case of increasing strain, greater equivalent interfacial thickness values, and higher mechanical energy loss values than those of composite containing oxidated fiber. An increase in glass transition temperature and apparent activation energy of the relaxation process, with respect to composite-containing commercial fiber, are also observed, which, altogether, allow for the statement that new matrix-fiber bonds are generated through the sulfonyl azide group, conferring greater strength to the interface, although it is less stiff than the one formed with oxidated fiber. Finally, the experimental results are in agreement with those obtained from Huet's rheological model. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 1197-1208 
    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: This paper reports on the study of the mechanical and dynamic properties of composites with an EPDM matrix and short fiber, either polyester or carbon, at three different fiber concentrations. In general, the properties prove to be dependent on fiber concentrations and type, in particular on the final ratio fiber length/diameter. This ratio ranges for carbon fiber over 35-45 and for polyester over 135-175, thus placing the former near the lower limit of acceptability. Evidence is supplied of the existence of adhesion between the matrix and the fiber, in the form of measurements of the swelling and dynamic properties, especially through variation of relative damping and the displacement of the dynamic glass transition temperature towards higher ranges. Composites present a marked property anisotropy.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 201-215 
    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: In dieser Arbeit werden die durch Oxidation mit Salpetersäure hervorgerufenen Veränderungen der spezifischen Oberfläche, Porosität, Oberflächenfunktionalität und der Faserdimensionen handelsüblicher Kohlenstoffasern untersucht. SEM-Untersuchungen ergaben keine Veränderungen, jedoch konnten durch Kryptonadsorptionsmessungen erhöhte spezifische Oberflächen-und Mikroporositätswerte nachgewiesen werden.Die oxidative Behandlung beeinträchtigt die Faserlänge und verringert, wenn auch nur geringfügig, den Faserdurchmesser und die Festigkeit, wie aus Messungen des Elastizitätsmoduls hervorgeht.Die durch volumetrische Messungen und XPS durchgeführte Funktionalitätsanalyse zeigt eine erhöhte Gesamtoberflächenazidität aufgrund einer Zunahme der Carboxygruppen. Längere Behandlung der Fasern vermindert den Gehalt an Hydroxygruppen an der Faseroberfläche.
    Notes: This work reports on the variations in specific surface, porosity, surface functionality and dimension of commercial carbon fibre subjected to oxidative treatment with nitric acid. Scanning electron microscopy (SEM) observation did not reveal any topographic changes on the fibres, although crypton adsorption evidences increases in specific surface and microporosity.Oxidative treatment has an effect on fibre length, although it also slightly reduces the fibre diameter and the fibre strength, as measured in terms of the elastic modulus.Functional analysis by means of volumetric measurements and X-ray photoelectron spectroscopy (XPS) reveals an increase in the overall fibre surface acidity through carboxy group increase. Prolonged treatment gradually removes hydroxy groups from the fibre surface.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 10 (1989), S. 256-260 
    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 analyzes the effects of the addition of a three-component dry type adhesive system on the properties of composite SBR (styrene-butadiene rubber) material containing 20 percent short polyamide (5 mm length and 60 μm diameter). The curing times are extended and green strength is doubled. The replacement of the silica component in the system by a natural silicate is not only feasible, but proves to be favorable for certain properties, such as the storage modulus E′, which becomes less sensitive towards temperature changes. Dynamic property measurements provide evidence of an additional dispersion corresponding to the matrix-fiber interface located around 40 to 50°C, which does not occur in the composites without adhesive. The activation energies of the main relaxation process of these materials are determined, amounting to 175 KJ/mol for the matrix and 250 KJ/mol for adhesive-containing composites, as a consequence of the formation of strong bonds between both phases.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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