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  • Chemical Engineering  (35)
  • Nickel coated graphite  (1)
  • 1
    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
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 35-39 
    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: Tensile properties of a poly(2-hydroxyethyl methacrylate) (PHEMA) network filled with various amounts of glass beads, in the dry and the equilibrium water-swollen states, have been studied below and above Tg. The temperature ranged from 5° C to 170° C and the volume fraction of the filler was up to 50 percent. In the glassy region it has been found that the temperature at which the transition from brittle to ductiel behavior occurs is increased by the presence of the filler. In the brittle zone the strength of the composites is decreased by the presence of the filler and can be predicted by using a finite element method; in the ductile zone, however, the strength of the composites reaches that of the unfilled polymer.In the rubbery region failure envelopes have been obtained for both dry and swollen PHEMA/glass bead composites. Using a double shift procedure all the data have been superimposed to obtain universal failure envelopes for the two different states. The dependence of the shift factors on filler content is discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 137-149 
    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 fundamental analysis of the mechanical response of composite media involves investigations on two levels of abstructions: the micro and the macro scale. These areas of study are known as micromechanics and lamination theory. This format is employed to treat a series of problems concerning (1) stiffness, creep, or viscoelastic properties; (2) strength and expansion properties for oriented continuous and short fibers; (3) randomly oriented fibers; (4) injection-molded materials; and (5) particulate reinforcements.
    Additional Material: 25 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 293-298 
    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: In this paper the effect of temperature and filler content φ on electrical resistivity of styrene-acrylonitrile polymer filled with iron or aluminium powders has been investigated. The resistivity of such composites decreases suddenly by several orders of magnitude at a critical volume concentration φc, which depends on the size distribution of particles and on thermal history. For filler content lower than φc, the resistivity decreases with increasing temperature, whereas for φ 〉 φc there is a sudden increase in resistivity at temperatures near the glass transition temperature of the polymeric matrix. This effect is more pronounced than the previously reported data on other composite systems.
    Additional Material: 11 Ill.
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  • 5
    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 hot drawing of extruded composite sheets can be used to control the orientation of both matrix and reinforcing fibers. A study was made of the effect of draw ratio on the properties of an extruded polystyrene sheet containing 0 to 1 percent of short glass fibers. An increase in draw ratio resulted in an increase in fiber orientation. A model of a rigid fiber rotating in an elongational flow field was used to describe the effect of draw ratio on the final orientation distribution. An increase in draw ratio also caused an increase in the amount of fiber breakage. A shear-lag analysis was used to estimate the extent of damage as a function of draw ratio. It was also found that the mechanical properties were dependent upon both the draw ratio and fiber concentration.
    Additional Material: 14 Ill.
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  • 6
    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: Recovery experiments above Tg have been performed on polymeric liquid crystal (PLC) - polystyrene (PS) blend sheets obtained from extrusion and subsequent hot drawing. The data reported show that a significant improvement of the dimensional stability of a drawn thermoplastic material can be obtained by adding a low percentage of non-compatible polymeric liquid crystals that are oriented during the hot drawing process. The fibrils formed act as a constraint for a certain amount of polymer surrounding them and consequently these highly oriented sheets, once exposed to high temperature, will mainly stress relax and do not creep. This effect disappears when the melting temperature of the oriented crystalline phase is reached. Compatible PLC-PS blends do not show any improvement on the dimensional stability compared to the unfilled matrix.
    Additional Material: 6 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1203-1206 
    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: Thermal treatment of amorphous poly(aryl-ether-ether ketone) below the glass transition temperature has been studied. The extent of aging was measured by differential scanning calorimetry. X-ray and Fourier transform infrared spectra were used to study both melt-cast and annealed samples. The effect of the thermal treatment of viscoelastic response was evaluated using creep tests. Aging has been shown to be accompanied by a marked change in the transport properties of the material.
    Additional Material: 5 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 1786-1795 
    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 possible multimodal sorption mechanisms in glassy amorphous poly-ether-ether-ketone (PEEK) are presented. By varying the penetrant-polymer affinity, experimental temperature, and external solvent activity, a broad range of sorption behaviors from ideal Fickian diffusion to limiting relaxation controlled kinetics is observed. In particular, water, methylene chloride, and n-heptane sorption kinetics are analyzed and interpreted on the basis of the multiple transport mechanisms. Low uptake liquid n-heptane sorption follows ordinary Fickian diffusion. Analogously, water vapor at low activity, is sorbed in small amounts in the same limiting mode while, at higher activities, the moderately higher penetrant uptakes induce slow relaxation coupled with ideal Fickian diffusion. The highly interacting methylene chloride leads to ideal Fickian diffusion only at very low activities, while anomalous non-ideal Fickian diffusion and limiting Case II and diffusion controlled swelling are observed at moderate and at high solvent activities, respectively. Limiting Case II sorption of methylene chloride in PEEK has been observed only at a very low temperature (-32°C). The optical microscopy observations of cryogenically fractured samples contacted with liquid methylene chloride at 5, 20 and 36°C revealed the presence of a sharp front moving linearly with the square root of time. Solvent induced crystallization in methylene chloride swollen samples was detected by means of differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS). Finally, sorption from liquid methylene chloride/n-heptane solutions with varying compositions are presented. The progressive increase of the more high sorbing methylene chloride concentration in the solutions, leads to the same wide variety of sorption behavior observed in the methylene chloride vapor sorptions. The gas chromatographic (GC) analysis indicated that the presence of methylene chloride enhanced the n-heptane sorption in the polymer.
    Additional Material: 19 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 11 (1971), S. 194-199 
    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 effects of temperature, strain rate and filler content on tensile properties of SAN/glass bead composites are studied. A point of discontinuity on the stress-strain curves for unannealed composites is investigated, annealing results in smooth curves with no discontinuities. A simple model for the filler effect on yield stress is suggested and shown to be in a good agreement with experimental data. A double shifting procedure to account for the temperature and filler effects on yield stress as a function of strain rate is proposed. A single master curve that can be represented by the equation: \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{\sigma yc}}{{{\rm 1 - 1}{\rm .21}\phi ^{{\rm 2/3}} }} = A + B\,{\rm ln (}\dot \epsilon a_T) $$\end{document} relates composite yield stress to strain rate, temperature and filler volume fraction.
    Additional Material: 7 Ill.
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  • 10
    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: A history dependent solubility model is generalized in accordance with the Dual Mode Sorption Theory to take into account a history dependency of effective water diffusion coefficients in epoxy resins, based on hypothesized microcavitational damage due to the combined effects of temperature and sorbed moisture. Sorption data presented in a different paper are analyzed in the light of a transport model in which part of diffusing molecules are completely immobilized in the formed microcavities. The nature of the hypothesized damaging process is in agreement with the diffusion coefficient depressions and solubility increases experimentally found and theoretically predicted by the model.
    Additional Material: 6 Ill.
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