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  • Chemistry  (30)
  • Nickel coated graphite  (1)
  • Dynamic properties
  • 1990-1994  (18)
  • 1985-1989  (13)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Stability of nickel coatings on carbon fiber preforms: A SEM investigation (1994)
    Springer
    Applied composite materials 1 (1994), S. 231-245 
    Details
    ISSN: 1573-4897
    Keywords: MMC ; Nickel coated graphite ; Squeeze casting ; Instable interface ; Electroplating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Metal Matrix Composites (MMC's) reinforced with continuous fibers were generally fabricated by a foil-sandwich technique or by liquid metal infiltration. Liquid metal infiltration may be used to cast final shapes in molds containing fiber preforms. It is also used to make composite wire from which may be fabricated panels and shapes by hot-press diffusion bonding or pultrusion. The major drawback of this method is that the molten matrix must wet the fiber for successful infiltration to occur, requiring special fiber surface treatments or matrix additives, and that, molten metals generally dissolve or degrade the fibers, necessitating a barrier coating on the fibers. All these problems can be solved using carbon fibers coated with metallic layers, e.g. nickel. This work analyses an easy method to produce modified carbon fibers by electroplating and the process of its recristallization. The topography of the growth front of the deposit has been studied. At temperatures higher than about 300° C an annealing under vacuum is required, because of the high reactivity of metal coating, nevertheless the heat treatment of metal deposit produces always an embrittled material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00567529
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of the applied field on the electrical properties of metal polymer composites (1988)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 9 (1988), S. 139-143 
    Details
    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: The effect of filler content and applied electrical field on the electrical resistivity of poly(methyl methacrylate) (PMMA) filled with aluminum particles was investigated. The resistivity of such composite suddenly decreases by several orders of magnitude at a critical volume concentration φc. In addition, for filler contents lower than φc, the PMMA/Al composite undergoes a transition from a high to a low resistance material in correspondence of a critical value of the external applied electrical field. This value has been related to thermal breakdown occurring in the regions between conductive particles. Moreover, the permittivity spectrum as a function of frequency is reported for composites of several filler contents, and the Lal and Parshad law was used to correlate the experimental data.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750090207
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  • 3
    Electronic Resource
    Electronic Resource
    The contribution of thermal stresses to the failure of Kevlar fabric composites (1988)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 9 (1988), S. 192-197 
    Details
    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: The mismatch in thermoelastic properties between fiber and matrix in Kevlar 49 fabric-epoxy composites is shown to result in significant thermal stresses with cool down from processing temperatures. Cooling generates local transverse tensile stresses that can potentially initiate microcracking at ambient conditions. A temperature reduction also places the curved fiber in the fabric composite in axial compression. This compression adds to the bending strain in the fiber, resulting in significant local reduction of its inherently low compressive load-bearing capability. The combination of thermal stresses and external compressive loads that are below ultimate values can cause local compressive failure of the fiber. The kink bands formed as a result of compressive failure of Kevlar fiber are expected to cause debonding between fiber and matrix and, therefore, are also potential sites for crack initiation. Thus, thermal stresses can contribute to the initiation of at least two damage mechanisms that may severely limit the compressive and flexural fatigue strength of Kevlar fabric composites at and below ambient temperature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750090305
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of water absorption on the behavior of E-glass fiber/nylon-6 composites (1991)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 12 (1991), S. 333-337 
    Details
    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: The effect of water absorption on the stress transferability across E-glass fiber/nylon 6 interface has been studied using the embedded single fiber composite technique. The behavior of silane coated fiber and untreated fiber composites after periods of water immersion were compared. The silane coating provided both higher interfacial shear stress transferability and protection from permanent water damage in the interphase region. It was found that water absorption in the nylon matrix reduced the shear stress transferability through plasticization of the matrix, weakening of the interface, and the development of tensile swelling stresses at the phase boundaries. In untreated materials the shear stress transferability was limited by decoupling of the matrix from the broken fiber ends by either interface slippage or local plane strain fracture in the interphase region near the fiber end. In the silane treated materials the shear stress transferability was limited by constrained yielding of the polysiloxane/nylon interphase at the fiber end, thus indicating plasticization of the matrix was the primary factor. After 20 days of water immersion, there was permanent deterioration of stress transferability in the untreated samples, but very little permanent damage in the treated samples.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750120507
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  • 5
    Electronic Resource
    Electronic Resource
    In-situ composites: Evaluation of the adhesion between the thermoplastic matrix and the fibers of liquid crystalline polymer (1992)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 13 (1992), S. 169-173 
    Details
    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: Mechanical properties of fiber reinforced composites depend on the formation of stable adhesive bonds between the constituents. In order to evaluate quantitatively the adhesion between liquid crystal polymer (LCP) fibers and a thermoplastic matrix of polycarbonate, the single fiber composite test (SFC), utilized for testing glass or carbon fiber composites, has been used. Neither chemical nor physical interaction has been found: the PC and LCP phases are completely incompatible. However, a mechanical friction between PC and LCP was observed during the drawing of the sample when the neck of the matrix started.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750130304
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  • 6
    Electronic Resource
    Electronic Resource
    Cure kinetics of dicyanate matrix polymers (1992)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 13 (1992), S. 191-196 
    Details
    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: The cure kinetics of two dicyanate resins were investigated by differential scanning calorimetry under isothermal and nonisothermal conditions. An autocatalytic kinetic model was proposed and a set of general kinetic parameters was calculated from the isothermal experiments. Good agreement between experimental data and the kinetic model has been obtained under different processing conditions, which demonstrated the validity and the usefulness of the analytical procedure and of the kinetic expression employed. Consequently, in its current form, the modeling methodology is capable of describing the degree of cure during a typical processing cycle and has the potential for comparing different resin formulations as well as the manifestations of cure in property development. Specifically, in this work the modeling methodology was tested using two distinct dicyanate resin systems while the development of the cure was also observed through dielectric analysis (DEA).
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750130307
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  • 7
    Electronic Resource
    Electronic Resource
    Wilhelmy plate studies of carbon fiber/viscous fluid systems (1993)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 14 (1993), S. 224-228 
    Details
    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: The use of Wilhelmy plate techniques for studying the interactions of fibers with fluids of variable viscosity is discussed. The influence of hydrodynamic effects of force (F) VS. DEPTH (z) plots is interpreted on the basis of surface tension-independent added terms of the constitutive equation of the Wilhelmy experiment. Wetting experiments using pseudoplastic fluids (polyethyleneglycol/water solution) show that viscoelasticity is indeed important in the interpretation of Wilhelmy plate experiments. The comparison of wetting experiments performed on untreated and plasma-treated carbon fibers showed that at low stage speed and fluid viscosity, surface chemistry and morphology determines contact angles. At higher stage speeds and viscosities and advancing and receding angles are affected by surface chemistry-independent and hydrodynamics-dependent added contributions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750140307
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  • 8
    Electronic Resource
    Electronic Resource
    Water sorption kinetics in poly(aryl ether ether ketone) (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 381-392 
    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 kinetics of diffusion of water from different activity vapors and liquid phase have been investigated in glassy amorphous poly(aryl ether ether ketcne) (PEEK) films at the temperature of 60°C and in glassy semicrystalline PEEK sheets at different temperatures, respectively. In the case of the amorphous PEEK films (250 μm thick) the data at low activity levels were interpreted by means of a purely Fickian mechanism. At higher activity levels the material has shown the presence of a relaxation process; in this case the data have been interpreted using a model proposed by Berens and Hopfenberg. Equilibrium sorption isotherm is also reported. Liquid water sorption in semicrystalline (30%) PEEK sheets (2 mm thick) has been determined to follow the classical Fickian mechanism. The water uptake values obtained for both amorphous and semicrystalline PEEK, confirm the good moisture and liquid water resistance of this kind of high performance thermoplastic polymer.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070370207
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  • 9
    Electronic Resource
    Electronic Resource
    Toughening epoxy resins by liquid crystalline polymers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 1465-1471 
    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: Toughening epoxy resins can be achieved by blending a low percentage of Liquid Crystalline Polymer with the thermoset. The processing technique consists of the spinning of blends of a thermoplastic (Ardel) with the LCP (PET/PHB60). The bundled filaments are subsequently dissolved in the uncured epoxy resin (Epon 825). After curing, the LCP phase separates from the matrix in the form of microfibers with a very high aspect ratio, which act as crack stoppers and improve fracture toughness of the material.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440816
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  • 10
    Electronic Resource
    Electronic Resource
    Calorimetric quality control of UV cured optical fiber-coatings (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 2077-2086 
    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 application of ultraviolet (UV)-curable polymeric coatings provides optical fibers with improved strength, microbending resistance, and long-term durability. To ensure constant optical properties of the glass fibers during their life, fully polymerized coatings are needed. Test methods capable of determining the degree of cure and the consistency of the polymeric materials used are therefore required by the fiber technology. This investigation deals with the description of a calorimetric test method for the direct determination of the prepolymer reactivity and its final degree of cure. The analytical technique uses a modified differential scanning calorimeter (DSC) capable of direct measurements of heat fluxes generated during the UV-activated polymerization of photoinitiated acrylic prepolymers. Finally, the degree of cure and the glass transition temperatures were determined for the polymerized coating also in presence of sorbed moisture.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330619
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