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  • Chemistry  (20)
  • MATERIALS, METALLIC  (1)
  • 1960-1964  (14)
  • 1955-1959  (7)
  • 1930-1934
  • 1
    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 faint emission of light by various classes and types of polymers when heated in the presence of oxygen, oxyluminescence, was studied by means of a photomultiplier tube and sensitive microammeter. Among the polymers with a carbon-carbon backbone, the polymers having the greater number of tertiary carbon atoms generally showed greater intensities of luminosity. Polystyrene was a notable exception to this generalization. The shape of the luminosity versus time curves varied with the type of polymer. It was also found that the emission of light did not stop instantly when the oxygen atmosphere was replaced by an inert gas, but rather followed an exponential type of decay. The rate of decay appeared to be different with different types of polymers. The intensities of luminescence and the times required to reach maximum or steady state luminescence were compared with oxygen uptake data for various polymers. In general there was a qualitative, but not necessarily quantitative correlation between the luminous intensities and polymer stabilities in the presence of oxygen.
    Additional Material: 9 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 8 (1964), S. 997-1006 
    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 oxyluminescence of polypropylene and polyethylene stabilized with various amounts of 4,4′-thiobis(3-methyl-6-tert-butylphenol) were studied and compared with oxygen uptake data. It was found that there was a correlation, although not linear, between the two methods. In the case of the stabilized polypropylenes, a pronounced aging effect was noticed. The oxyluminescent behavior of stabilized polyethylene was somewhat different from that of stabilized polypropylene. The temperature coefficients of the oxyluminescence of polypropylene, polyethylene, nylon 6, polystyrene, polyurethane and polymethyl methacrylate were obtained. From these data the apparent activation energies for the light-emitting reaction were calculated. For the olefin polymers, these values are close to the activation energies of the oxidative degradation reaction obtained by other means. Both polyethylene and polymethyl methacrylate have different activation energies below their transition points as compared to higher temperature, indicating a different mode of reaction in the solid state from that occurring in the melt. An interesting transition luminescence, which was more pronounced in the absence of oxygen, was observed in the case of polyethylene.
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 4 (1962), S. 129-138 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 4 (1958), S. 102-113 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Superatmospheric pressures greatly reduce the temperature differences in nucleate boiling of or ganic liquids. Since nucleate boiling is characterized by bubble formation at the heating surface, it seems logical to investigate the pressure difference that causes bubble formation. It has been found that for organic liquids the difference in vapor pressure corresponding to the temperature difference behaves in a regular manner with pressure but does not vary greatly. This regular behavior permits prediction of temperature differences at higher pressures with a knowledge of only vapor-pressure and boiling data at one pressure. New boiling data have been obtained in the investigation.
    Additional Material: 22 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 10 (1964), S. 656-660 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: By using a special surface thermocouple Moore and Mesler have measured large temperature fluctuations during nucleate boiling of water on chromel P surface. They found that the temperature dropped 20° to 30°F. in about 2 msec. but required 10 to 20 msec. to recover. They have postulated that the surface was cooled during initial bubble growth by evaporation of a microlayer into the bubble. To test this hypothesis a technique was developed to photograph a bubble growing from an artificial site as the surface temperature was measured.Temperature fluctuations were recorded on an oscilloscope which automatically triggered the bubble photographs by means of a time delay unit and flash tube. Photographs of bubbles were taken at 1 μsec. exposure time and ranged from about 10 μsec. after the start of the temperature drop to about 1 msec. before the start of another cycle. The photographs show that the surface cools during bubble growth and recovers during bubble departure.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 4 (1958), S. 90-96 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rates of flow of pure gases, both those with no adsorption and those with appreciable adsorption, were studied as a function of pressure level, pressure drop, and temperature for flow through 1/2-in.-diameter cylindrical plugs of activated carbon and of unsintered Vycor glass. Adsorption isotherms for the pure gases on Vycor glass were measured over the range of variables covered in the flow studies. A few measurements were made for bulk liquid flowing through a Vycor plug.Permeabilities, which are proportional to the rate of flow per unit of pressure drop, were satisfactorily correlated for hydrogen, helium, argon, and nitrogen by employing existing gas-phase flow theory. Permeabilities considerably larger than the values predicted from the nonadsorbed gas correlation, sometimes more than seventeen times as large, were observed for ethylene, propylene, and isobutane flowing through a Vycor plug. For the hydrocarbon-Vycor systems, permeabilities for vapor flow are as much as sixty times larger than for bulk liquid flow.The unusual flow phenomena for the hydrocarbon-Vycor systems are attributed to a rapid transport in the adsorbed layer. The total transport is treated as being the sum of gas-phase and adsorbed-layer flow. An equation describing adsorbed-layer movement is derived by utilizing a force balance together with thermodynamic principles. The resulting equation has just one empirical constant, and its use requires adsorption-isotherm data. It correlates very well the surface flow rates for the major range of the variables covered in this investigation. Rate measurements were made for adsorbed-layer concentrations ranging from about one tenth of a monolayer up through the capillary condensation region. Deviations in the one constant form of the equation are observed below one tenth of a monolayer. The available literature data on flow in adsorbed layers are reasonably well correlated by the same equation.
    Additional Material: 11 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 7 (1961), S. 620-624 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The surface temperature during nucleate boiling was measured with a special thermocouple so designed as to measure the temperature of a small area and to have an extremely rapid response time. The surface temperature was found to drop occasionally 20° to 30°F. in about 2 msec. during the boiling of water. This indicates a rapid extraction of heat during a short time interval. The significance of this observation is that it provides an important new clue to an understanding of nucleate boiling. A hypothesis is advanced to explain these observations.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 2 (1959), S. 198-202 
    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: Polymers and copolymers were prepared from the acetoxy derivatives of m- and p-hydroxybenzoic acids. Molecular weights of over 20,000 were obtained for poly(m-hydroxybenzoic acid) and copolymers containing up to 60% para isomer. These polyesters were crystalline, and the degree of crystallinity increased as the para isomer content was increased. Blocks of the high-melting, insoluble poly(p-hydroxybenzoic acid) tend to form in copolymers containing a high proportion of the para isomer because of the difference in reactivity of the two isomers. Copolymers containing at least 55% of the meta isomer are soluble in several classes of solvents. The copolymers do not have sharply defined melting points, but have softening temperatures ranging from 150°C. to over 300°C. Tensile strengths of approximately 10,000 psi and elongations of about 6% to 40% were obtained. The polymers were relatively stable to oxidative degradation, but not to hydrolysis.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 4 (1960), S. 219-224 
    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: Attention is called to the variables effecting the extraction of polypropylene. Under controlled conditions, the extraction of polypropylene with first diethyl ether and then n-heptane will give reproducible results. It is necessary to extract with heptane in an atmosphere of nitrogen. The values obtained by the extraction procedure described are regarded as relative measures of the amounts of isotactic, stereoblock and atactic material present in a sample. Extraction with n-heptane alone by this procedure also gives the same value of relative isotacticity. Infrared studies showed that the ether soluble fractions were essentially atactic, while the n-heptane-soluble or stereoblock material possessed a degree of order corresponding to 20-40% isotactic polypropylene.
    Additional Material: 2 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 7 (1963), S. 959-969 
    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 initial stages of isotactic polypropylene oxidation were investigated by oxidizing at 130°C. to various extents up to 10 ml. of oxygen consumed per gram of polymer. The development of infrared absorption bands in the carbonyl regions was followed, as increasing amounts of oxidation occurred. The oxidation uptake curves showed that both autocatalytic rate and induction time depended primarily on the thickness of the sample, contrary to the case of polyethylene. This indicated the initiation process was primarily diffusion controlled for samples of the thickness range studied. The presence of copper shortened the induction times and increased the autocatalytic rate. In this case, the dependency of the induction time on thickness was less. Dielectric data showed that polypropylene became unsuitable electrically at about the point where the autocatalytic oxidation set in. It was also found that the effects of prior exposure to oxidative conditions were cumulative to a considerable extent, and thus resulted in shorter induction times.
    Additional Material: 6 Ill.
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