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  • 1
    Electronic Resource
    Electronic Resource
    Characterization and role of an elastomeric interphase on carbon fibers reinforcing an epoxy matrix (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 568-577 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Oxidized carbon fibers were coated using an on-line filament winding process with an elastomeric adduct crosslinkable and compatible with an epoxy matrix. The coating and modifications of the epoxy network were studied by dynamic mechanical measurements. Assuming that apparent activation energies of the secondary relaxation βe of the epoxy network and main relaxation αa of adduct are very different, it is possible at low frequencies to separate the two peaks. The composite material can be described as a three phase system: an epoxy network as matrix, carbon fibers, and a soft interlayer. The mechanical behavior of unidirectional composite materials studied by impact and bending tests is strongly dependent on the presence and the thickness of the coating at the carbon fiber surface.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280905
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  • 2
    Electronic Resource
    Electronic Resource
    Polyuréthannes à propriétés émulsifiantes et électrolytiques, 1. Cinétique de condensation des alkylimino-2,2′ diéthanols et de leurs dérivés sulfobétaïniques avec divers monoisocyanatesA la demande de l'auteur, la publication a été retenue. (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1693-1717 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This work deals with model reactions allowing the synthesis of low-molecular-weight polyurethanes with electrolytic and emulsifier properties. The kinetics of addition reactions of 2,2′-alkyliminodiethanols (3a - c) and their ammonium sulfonate derivatives 5 and 6 with propyl (8a) and cyclohexyl isocyanate (8b) were studied in DMSO and in the bulk. The tertiary amino groups of 3 exhibit catalytic effects, whereas the ammonium sulfonate internal salts inhibit the reaction. 8a is 2 - 3 times more reactive than 8b and the addition rates decrease with increasing R. Autoassociations (OH ··· OH) should mainly be intramolecular because of the proximity of the alcohol groups. In bulk the 8a + 3 additions apparently follow second order kinetics. On the other hand, the third order law must be taken into account with 8b. In contrast, in DMSO, due to the strong (solvent, —OH and/or —NCO) complexations, the kinetics do neither follow the simple second order, nor the third order law. By the use of two successive second order kinetics, diols were found more reactive than their monoalcohol-monocarbamate derivatives. However, the difference in reactivity decreases with increasing reaction temperatures. Sulfobetaine units may be inserted into the polyurethane chains if diols with ammonium sulfonate groups are used as comonomer, but their weak reactivity must be taken into account.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890724
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  • 3
    Electronic Resource
    Electronic Resource
    Polyuréthannes à propriétés emulsifiantes et électrolytiques, 2Partie 1: cf.1. Cinétique de polycondensation en solution des alkylimino-2,2′ diéthanols avec le diisocyanate d'isophorone. Etude par 1H et 13C NMR (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1719-1737 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 13C NMR analysis of carbamates and substituted ureas as model compounds, derived from 5-isocyanato-1,3,3-trimethylcyclohexylmethyl isocyanate (isophorone diisocyanate) (3), allowed the quantitative determination of global conversions of hydroxyl and NCO groups. The individual conversions of the two NCO groups, as observed in the polycondensations of 2,2′-methylimino- and 2,2′-dodecyliminodiethanol (1a and 1b) with 3 in toluene, were examined. The primary NCO group of 3 was found to be two times more reactive than the secondary one. The global kinetics of the polycondensations followed the 2nd and 3rd order for conversions lower than 50%. Beyond 50% of conversion, zero order kinetics were observed because of the decrease of the rate due to the steric hindrance of both cyclohexyl and alkyl residues. Alkyl radical length in 1 and hydroxyl auto-association equilibria were found to have the same effect on polycondensation as on condensation.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890725
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Simultaneous kinetic and microdielectric studies of some epoxy-amine systems (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2911-2921 
    Details
    ISSN: 0887-6266
    Keywords: epoxy ; amine ; microdielectrometry ; conductivity ; conversion ; glass transition temperature ; curing ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Three reactive epoxy-amine systems based on diglycidyl ether of bisphenol A (DGEBA) with 4,4′-diaminodiphenylsulfone (DDS), 4,4′-methylenebis [3-chloro 2,6-diethylaniline] (MCDEA), and 4,4′-methylenebis [2,6-diethylaniline] (MDEA), were studied during isothermal curings at 140 and 160°C. The simultaneous kinetic and dielectric studies allow to express conductivity, σ, in terms of conversion, x, and of glass transition temperature, Tg. The conductivity, σ0, of the initial monomer mixture and, σ∞ of the fully cured network are measured. It is found that: The glass transition temperature, Tg, versus conversion, x, curves follows the equation of Di Benedetto modified by Pascault and WilliamsThere exists a linear relation between log σ/log σ0 and Tg.So, it is possible to predict both kinetic and dielectric behaviors of these epoxy-amine systems by the knowledge of Tg0, ΔCp0, and σ0, respectively, glass transition temperature, heat capacity, and conductivity of initial monomer mixture, Tg∞ and ΔCp∞, and σ∞, respectively, glass transition temperature and heat capacity and conductivity of fully cured network. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2911-2921, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Morphology of unsaturated polyester resin-additive blends (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1585-1590 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 morphologies and impact behavior of blends based on an unsaturated polyester matrix and different added rubbers were studied by scanning electron microscopy (SEM). These rubbers were prepared from a carboxy-terminated acrylonitrile-butadiene copolymer (CTBN). The introduction of an epoxy-terminated triblock copolymer (ETON) by exchanging 10% by weight of the CTBN rubber compatibilizes the initial blend by reducing the interfacial tension between the components. Consequently, the morphology of dispersed phase was modified: decreasing of the particle size and reducing the number of large particles. For a blend with 5 phr of rubber, Charpy impact behavior was enhanced and the number of catastrophic failures was reduced. This study displays the existence of relationships between the interfacial tension between components and the morphology of the resulting materials.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760302405
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  • 6
    Electronic Resource
    Electronic Resource
    Influence of chain flexibility and crosslink density on mechanical properties of epoxy/amine networks (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 1572-1580 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Blends of a bisphenol A diglycidyl ether prepolymer and an aliphatic diepoxy diluent crosslinked with a cycloaliphatic diamine were studied. These model networks have the characteristic that the crosslink density and the chain flexibility increase with the amount of diluent. These combined effects were studied by observing their mechanical properties. The decreases in the Young's modulus and the ultrasonic modulus were associated with the secondary thermomechanical relaxations that have been recorded and identified. Pre-plastic and plastic behaviors were discussed in terms of flexibility and crosslink density. A linear relationship was established between pre-plastic activation volume and crosslink density at temperatures lower than the activation of molecular chain motions responsible for the sub-Tg relaxations. At 0°C, a temperature above these secondary transitions, the higher the flexibility, the more defect nucleation and propagation increased. The work hardening rate and the upper yield stress decreased as the amount of diluent was increased. Fracture toughness was improved as the amount of diluent was increased. Crack propagation was related to the ability of the networks to deform plastically.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760312204
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