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  • Polymer and Materials Science  (17)
  • permeation  (2)
  • Instable interface  (1)
  • Nickel coated graphite  (1)
  • 1995-1999  (6)
  • 1990-1994  (12)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied composite materials 1 (1994), S. 231-245 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1365-1370 
    ISSN: 0887-6266
    Keywords: polyketone terpolymer ; water vapor ; permeation ; clustering ; sorption ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Water transport in a polyketone terpolymer was analyzed performing both sorption and permeation experiments. Water vapor sorption tests were conducted at four temperatures (35, 45, 55, and 65°C) and at several activities. The analysis of sorption isotherms revealed the occurrence of water clustering. A reduction of the endothermicity of mixing as the amount of sorbed water increased was observed which is consistent with significant association of penetrant molecules in the polymer. Permeation experiments performed at 35°C at upstream pressures ranging from 4 to 25 Torr showed evidence of a reduction in water diffusivity as function of sorbed water concentration which is a typical indication of penetrant aggregation. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 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 41 (1990), S. 2691-2704 
    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: Blends of polymethylmethacrylate (PMMA) and poly-ε-caprolactone (PCL) were prepared and characterized. The analysis of the glass transition temperature indicates no compatibility of the two polymers, which segregated into two distinct phases. The fracture strength of the blends can be explained on the basis of a constitutive model of spheres of PCL embedded in a PMMA matrix. The trend of water sorption confirms the hypothesis of phase segregation of PCL in the glassy matrix of PMMA.
    Additional Material: 7 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 1261-1268 
    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 demand for heat-stable and easily processable polymeric materials with good gasbarrier properties is becoming more and more important due to the advent of new technological applications in the field of food packaging. A renewed interest has arisen for a polyketone class of polymers, which seems to fulfill these requirements. Our attention has been focused on a polyketone terpolymer (0.93 : 0.07 : 1 ethylene/propylene/carbon monoxide) in order to determine the transport properties and to relate them to the polymer structure. Permeability tests have been performed at three different temperatures (25, 35, and 45°C) with three different gases (helium, oxygen, and carbon dioxide). Permeabilities, diffusivities, and solubilities have been evaluated. Their dependence on temperature was interpreted on the basis of permeation and diffusion apparent activation energies (Ep and Ed) and of heats of solution (ΔHs). The investigated polymer has been found to be rubbery at the test temperature (glass transition temperature is about 17°C), but the detected permeabilities are comparable to those of glassy polymers widely used for packaging applications. The experimentally determined diffusion coefficients have been related to the semicrystalline nature of the polymer and to the different dimensions of the gas adopted in the investigation. The gas-solubility coefficients determined from permeability measurements were related to the force constant of the gas molecules in the Lennard-Jones (6-12) potential field equation. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 1525-1535 
    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: Blends of poly(3-hydroxybutyrate)-poly(3-hydroxyvalerate) (PHBV) and poly(L-lactides) (PLLA) have been prepared by solvent casting. Compatibility, thermal behavior, morphology, and mechanical properties of systems with various compositions were studied using differential scanning calorimetry (DSC), dynamic mechanical measurement, tensile tests, scanning electron microscopy (SEM), and wide-angle X ray (WAXS). Glass transition temperature of solvent cast materials, detected by dynamic mechanical analysis (DMA), showed partial molecular interactions between PHBV and PLLA. Crystallinity of the PLLA phase slightly decreased with increasing amount of PHBV, confirming the partial dispersion of PLLA in the PHBV phase. Mechanical properties were analyzed with theoretical models able to predict the behavior of heterogeneous systems. Phase separation was confirmed by SEM observations. © 1994 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 2403-2407 
    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: Sorption of distilled water in a cellulose-based hydrogel is presented. The examined system is based on a mixture of sodium salt of carboxymethylcellulose and hydroxyethylcellulose, crosslinked with divinilsulphone. The effect of chemical composition, manufacturing procedures, as well as desiccation protocols on equilibrium water uptake was investigated. Experimental results were interpreted in terms of crosslinking density, presence of ionic groups on the backbone, as well as macroscopic sample morphology detected by electron scanning microscopy. The reported results evidence the possibility to bias the process parameters in order to obtain hydrogels characterized by the desired water sorption levels. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1269-1280 
    ISSN: 0887-6266
    Keywords: ionomer ; permeation ; diffusion ; sorption ; gas ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Transport properties of several gases in two ethylene-acrylic acid ionomers characterized by a different amount of acrylic acid groups and percentage of neutralization have been investigated. Sorption and permeation experiments have been performed with N2, O2, CO2, CH4, C2 H6, and SF6 in the 25-65°C range and with C3H8 only at 25°C. Gas permeabilities, diffusivities, and solubilities were evaluated along with activation energies and heats of solution. Data obtained in the present investigation were compared to analogous results reported in literature for polyethylene to better highlight the effect of ionic aggregates on the gas transport mechanism. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 2723-2737 
    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 possibility of improving processability of engineering polymers was studied in this work. Low percentages of a thermotropic liquid crystalline polymer supplied by Bayer Co. were added to the polyetherimide Ultem. The thermal and morphological analysis revealed a two phase system. Rheological measurements in shear flow were carried out in the temperature range of the existence of the mesophase. A significant drop of ∼ 30% in the Ultem viscosity occurs even with 5% w/w TLCP. The influence of the addition of the thermotropic polymer on the mechanical properties of Ultem was also investigated. Moreover, the morphological analysis of the unfilled polymers and of the blends was performed and related to their rheological and mechanical behavior.
    Additional Material: 15 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 1163-1174 
    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 viscoelastic properties of the amorphous and semicrystalline PEEK and of a PEEK-based composite (APC2) have been analyzed as a function of the aging time and related free volume relaxation, at temperatures close to the glass transition temperature. The effect of thermal treatments (physical aging) on the polymer amorphous phase of the three systems is presented. Creep tests approaching the “zero stress” were performed on samples subjected to different thermal histories. The presence of a second phase, namely crystallites and fibers, determines a loss of the mobility of the polymeric amorphous chains and consequently a decrease of the rate of free volume relaxation.
    Additional Material: 9 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 839-844 
    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
    Additional Material: 8 Ill.
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