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  • 1
    Electronic Resource
    Electronic Resource
    Curing mechanism and thermal properties of epoxy-imidazole systems (1989)
    s.l. : American Chemical Society
    Macromolecules 22 (1989), S. 99-104 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00191a020
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  • 2
    Electronic Resource
    Electronic Resource
    Ethylene evolution from various developing organs of olive (Olea europaea) after excision (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 51 (1981), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ethylene evolution from leaves, stems, inflorescences and fruits of the olive plant (Olea europaea L.) cv. Manzanillo was studied at various stages of their development. Mature non-growing organs, particularly leaves, have a constant, low, and uniform rate of ethylene evolution. Ethylene evolution from detached mature olive leaves was constant during the first 12 h after excision. Leaves on shoots maintained in vitro kept a constant rate of ethylene evolution for at least the first 5–6 days. Leaf injury significantly increased ethylene evolution. Ethylene evolution from injured and non-injured control leaves could be markedly inhibited aminoethoxyvinylglycine (AVG) applied to the leaves or fed to the shoot. The use of excised olive shoots and leaves as an in vitro model system for studies of induced metabolic processes such as abscission and developing water stress was suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1981.tb00875.x
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  • 3
    Electronic Resource
    Electronic Resource
    Mass spectrometric measurement of zeatin glycoside levels in Vinca rosea L. crown gall tissue (1982)
    Springer
    Planta 154 (1982), S. 273-276 
    Details
    ISSN: 1432-2048
    Keywords: Crown gall ; Cytokinin ; Mass spectrometry (cytokinins) ; Vinca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The range of zeatin glycosides found in crown gall tissue of Vinca rosea L. has been quantified using a mass spectrometric isotope dilution procedure. Problems in the quantitative analysis of cytokinins in plant extracts are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387874
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  • 4
    Electronic Resource
    Electronic Resource
    Gibberellins in mature apple seeds — contaminants? (1980)
    Springer
    Planta 147 (1980), S. 376-377 
    Details
    ISSN: 1432-2048
    Keywords: Gibberellin (apple seeds) ; Pyrus ; Seeds (gibberellin)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evidence is presented that gibberellins A4 and A7, previously identified (Sinska, I., Lewak, St., Gaskin, P., MacMillan, J., Planta 114, 359–364, 1973) in extracts of mature apple (Pyrus malus L.) seeds, were present primarily as contaminants. The facts supporting this conclusion are: a) the ratio of GA4 to GA7 was similar to that of a standard mixture; b) the concentrations were extremely high; and c) the ratio of GA4 to GA7 did not change during stratification, as had been reported when extracts were bioassayed (Sinska, I., and Lewak, St., Physiol. Vég. 8, 661–667, 1970).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379847
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  • 5
    Electronic Resource
    Electronic Resource
    Yield and fracture behaviour of cross-linked epoxies (1993)
    Springer
    Journal of materials science 28 (1993), S. 4442-4450 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The yield stress and fracture energies of a series of cross-linked epoxy resins were studied in order to correlate the macroscopic mechanical properties with the polymer microstructure. Five networks with varying cross-link densities were synthesized by reacting a homologous series of epoxy resins with stoichiometric quantities ofm-phenylenediamine. For all the networks, the yield stress decreased with increasing temperatures in accordance with the predictions of the Eyring theory of viscosity. At constant temperatures, the yield stress decreased with increasing molecular weight between cross-links. The fracture studies revealed two distinct types of crack propagation behaviour above and below approximately 0 °C. Below 0 °C the cracks propagated in a stable and continuous manner, while the crack propagation behaviour changed to an unstable “stick-slip” mode as the test temperature was increased above 0 °C. For unstable crack growth, the fracture energies for crack initiation increased with increasing temperature, while the fracture energies for crack arrest were, within the limits of experimental error, independent of temperature. The crack arrest fracture energies were similar in magnitude to the fracture energies for stable crack propagation. An empirical power-law type correlation was observed between the glassy arrest fracture energies and the average molecular weight between cross-links. Micrographs of specimens which failed by the unstable, “stick-slip” mode revealed characteristic plastic deformation zones which highlighted the positions of crack initiation and arrest along the crack path. The deformation zone widths were observed to increase with increasing test temperatures, providing evidence of greater localized plastic deformations and higher fracture initiation energies at higher temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01154954
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  • 6
    Electronic Resource
    Electronic Resource
    Temperature effects on fatigue crack growth in polycarbonate (1976)
    Springer
    Journal of materials science 11 (1976), S. 231-238 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The fatigue behaviour of a high strength thermoplastic, polycarbonate, has been investigated as a function of temperature. Fatigue crack growth properties were measured in the temperature range of 100 to 373 K and were analysed using a fracture mechanics approach. Fatigue behaviour was found to be related to the fracture toughness of the material. This correlation with fracture toughness was used to develop an empirical model based on the toughness for describing the effect of temperature on fatigue crack growth, and to consider fatigue in terms of the secondary losses of the polymer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00551432
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  • 7
    Electronic Resource
    Electronic Resource
    Mechanical behavior of gradient polymersPresented at the Symposium on Structure-Property Relationships in Polymeric Networks, 87th National AIChE Meeting, Boston, MA, Aug. 19-22, 1979. (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 1465-1473 
    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: Gradient polymers are multicomponent networks which contain a spatial gradient in the concentration of the components in the blend. In this study, the properties of a system of gradient polymers consisting of a rubbery addition to a glassy matrix [poly(methyl methacrylate)] and a glassy addition to a rubbery matrix [poly(2-chloroethyl acrylate)] were investigated. Dynamic mechanical spectroscopy was used to characterize the compatibility of the polymers. The PMMA matrix gradients were found to be incompatible, while the PCIEA matrix gradients and the interpenetrating network exhibited compatibility. The tensile properties and the fracture strength of the polymers were measured and interpreted in terms of the composition and the deformation mechanism of the materials.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260503
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  • 8
    Electronic Resource
    Electronic Resource
    The fabrication and characterization of polymer optical conductors (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 2231-2239 
    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: Polymer microstructures were evaluated as thin film optical conductors. The polymer waveguides were fabricated from a photosensitive silicone polymer by selectively crosslinking the polymer with the near-ultraviolet radiation from an argon ion laser. The optical transmittance properties of curved and linear microstructures were characterized using an optical sensing technique. For the curved guides, an exponential decay in the intensity of transmitted light with guide length was observed. The linear guides exhibited an oscillatory relationship between output intensity and length over a range of 2 mm in length. The nature of the results for the linear guides was explained by considering the variations in the refractive index across the polymer microstructure and by comparison with the optical behavior of graded-index glass fibers.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070290626
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization of imidazole-cured epoxy-phenol resins (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1557-1566 
    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: The physical and chemical properties of the diglycidyl ether of bisphenol A (DGEBA) cured with different concentrations of bisphenol A (BPA) and 2-ethyl-4-methylimidazole (EMI-24) were examined using Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical and dielectric analyses, and solvent extraction studies. The effects of the phenol-epoxide and the secondary hydroxyl (R-OH)-epoxide reactions on the network formation process were analyzed using a recursive modeling technique to obtain expressions for the weight-averaged molecular weight, the weight fraction solubles, and the gel point as a function of the extent of cure and the epoxide-phenol reactant ratio. The sol fraction and the gel point predictions from recursive modeling studies of the network formation process agreed with the results obtained from the extraction studies. The results from the network modeling studies were also related to the thermal and rheological properties of the resin during cure.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420609
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  • 10
    Electronic Resource
    Electronic Resource
    Analysis of the cure kinetics of epoxy/imidazole resin systems (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 721-738 
    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: The reaction kinetics for the cure of epoxy resins with imidazoles were determined from Fourier transform infrared spectroscopy and differential scanning calorimetry studies. The diglycidyl ether of bisphenol A and phenyl glycidyl ether were cured with various concentrations of 2-ethyl-4-methyl-imidazole ranging from 4.0 to 100.0 mol %. The first step in the curing process is the formation of epoxide/imidazole adducts. These adducts initiate the etherification reaction which crosslinks the resin. The kinetics were determined and confirmed for both the adduct and the etherification reactions as a function of the imidazole concentration. A model was developed and used to predict the concentrations of the unreacted epoxide groups and the reaction products for a wide range of imidazole concentrations and cure temperatures.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070390321
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