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  • 1975-1979  (8)
  • 1965-1969  (1)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 253 (1975), S. 114-119 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Eine Serie der Polystyroldispersionen wurde unter Verwendung der verschiedenen Kombinationen von oberflächenaktiven Agentien und Initiatoren hergestellt. Die Kinetik der Koagulation dieser Latices gegen Bariumchlorid wurde untersucht. Das Oberflächen-potential für Latices, die unter Verwendung von Kalium-persulfat hergestellt wurden, war größer als das für die mit Wasserstoffperoxyd hergestellten Latices. Die Daten über die Hamaker-Konstante zeigten auch die ähnliche Tendenz. Das Oberflächenpotential und die Hamaker-Konstante für diese Latices bestätigten, daß sie durch die gebrauchten oberflächenaktiven Agentien beeinflußt werden.
    Notes: Summary A series of polystyrene latex dispersions has been prepared using different combinations of surfactants and initiators. The kinetics of coagulation of these latices against barium chloride has been investigated. The surface potential for latices prepared using potassium persulphate was found to be larger than that for latices prepared using hydrogen peroxide. The data on theHamaker constant proved to have a similar trend. The surface potential and theHamaker constant for these latices proved to be affected by the surfactant used.[⇃]
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 253 (1975), S. 538-543 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Styrol-Acrylnitril-Mischpolymer-Latices wurden unter Verwendung von Wasserstoffperoxyd als Initiator von Emulsionspolymerisation hergestellt. Verteilungen der Partikelgrößen wurden durch !Messen des Teilchen-Durchmessers auf Elektronenmikrographien bestimmt. Die chemische Zusammensetzung der Latex-Teilchen wurde durch Elementar-Analyse festgestellt. Stabilität und elektrophoretische Beweglichkeit dieser Latex-Dispersionen gegen einfache inorganische Elektrolytlösungen wurden untersucht. Der Wert der kritischen Koagulationskonzentration nahm mit abnehmendem Anteil von Acrylnitril in den Polymer-Partikeln zu. Der Wert desStern Potentials war unabhängig von der chemischen Zusammensetzung der Polymere. Der Unterschied in der Stabilität scheint vorwiegend auf den Unterschied der Anziehungsenergie zwischen Partikeln zurückgeführt werden zu können, d. h. dieHamaker Konstante nimmt beinahe geradewegs mit der Zunahme des Gehaltes von Acrylnitril im Mischpolymer zu.
    Notes: Summary Styrene-acrylonitrile copolymer latex dispersions were prepared using hydrogen peroxide as an initiator by emulsion polymerization. Particle size distributions were determined by measuring the diameter of particles on electron micrographs. The chemical composition of the latex particles was determined by elemental analysis. The stability and electrophoretic behaviour of these latex dispersions against simple inorganic electrolyte has been investigated. The value of the critical coagulation concentration was found to increase with the decrease of the fraction of acrylonitrile in the polymer particles. The value ofStern potential calculated was found to be independent on the chemical composition of polymers. The difference present in the latex stability seems to be mainly due to the difference in the attractive energy between particles, i.e., theHamaker constant increases almost linearly with the increase of the content of acrelonitrile in the copolymer.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 255 (1977), S. 105-110 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Eine Serie der Styrol-Methyl-Methacrylat (SM) und Styrol-Methacrylsäure (SA) Mischpolymer-Latices wurde unter Verwendung von Polyoxyäthylennonylphenyläther als oberflächenaktives Agents und Kaliumpersulfat als Initiator von Emulsionspolymerisation hergestellt. Wenige Carboxylgruppen in beiden Polystyrol-Latex-und Styrol-Methyl-Methacrylat-Mischpolymer-Latices wurden gefunden. Stabilität und elektrophoretische Beweglichkeit dieser Latices gegen Bariumchlorid würden untersucht. Die Werte der kritischen Koagulaiionskonzentration (k. k. k.) nahm mit Zunahme des Gehaltes an Methacrylsäure für SA-Latices zu, während sie fast unabhängig vom Gehalt an Methyl-Methycrylat für SM-Latices sind. Die Wirkungen des Methyl-Methacrylats und der Methacrylsäure auf die Änderung der Hamaker Konstante sind meistens identisch. Der Unterschied in k. k. k. zwischen SM- und SA-Latices scheint hauptsächlich auf den Unterschied in der elektrischen Abstoß durch Carboxylgruppen auf der Oberfläche zuzückgeführt werden zu können.
    Notes: Summary Series of styrene-methyl methacrylate (SM) and styrene-methacrylic acid (SA) copolymer latices have been prepared by emulsion polymerization using polyoxyethylene nonyl phenyl ether as emulsifier and potassium persulphate as initiator. Trace carboxyl groups were detected both in polystyrene latex and styrene-methyl methacrylate copolymer latices. The stability and electrophoretic behaviour of these latices against barium chloride have been investigated. The values of the critical coagulation concentration (c. c. c.) increased with increasing methacrylic acid content for SA series latices, while they are almost independent of methyl methacrylate content for SM series latices. The effects of methyl methacrylate and methacrylic acid on the change in Hamaker constant were found to be almost identical. The difference inc. c. c. between SM and SA series latices seems to be due to the difference in electrical repulsion caused mainly by carboxyl groups on the surface.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 254 (1976), S. 768-768 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 1321-1330 
    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: Dynamic mechanical properties of poly(methyl methacrylate) (PMMA) filled with mica flakes (M) or glass beads (G) were investigated as functions of particle size and filler concentration. With increasing particle size, dynamic modulus E′ slightly decreases for system G, while it increases rapidly at first and then approaches the limiting value for system M. Primary dispersion temperature Tα increases with increasing filler concentration. With increasing particle size, Tα decreases for system G but increases for system M. For the mica-filled system, the effect of particle size on the modulus can be explained in terms of orientation of the filler by comparing the experimental data with Wu's and Padawer and Beecher's predictions of the modulus. In order to explain the dependence of Tα on particle size and concentration, an equation for Tα has been proposed: \documentclass{article}\pagestyle{empty}\begin{document}$ T_\alpha = K_f \ln S^ \cdot $\end{document} where Kf is a constant and S is the specific surface area of filler per gram of polymer. For system G, Tα can be expressed by the above equation, irrespective of particle size and filler concentration. In the case of system M, it is suggested that Tα is affected also by orientation in addition to the surface area of the filler.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 2113-2120 
    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 dependence of critical strain on time was determined at -20° and 20°C with a Bergen elliptical strain device for unmodified and rubber-modified polystyrenes immersed in n-alcohols. Critical strain ∊c decreased with time and attained a lower limiting value ∊cl at long times. The value of ∊cl decreased with increasing chain length of the n-alcohol and with increasing temperature, while it increased with increasing rubber content. In order to elucidate the mechanism of solvent crazing at longer times, the degree of equilibrium swelling Sveq and the diffusion coefficient D were also determined by sorption experiment. The lower limiting value of critical stress σcl was correlated to the value of Sveq, irrespective of the rubber content. The At, the time necessary to attain ∊cl, was regarded as the time needed for the thin layer of polymer surface to absorb the liquid to equilibrium for craze formation. The thickness of such a layer was estimated to be about 0.1 μm by using the experimental data of At and D. The predominant mechanism of solvent crazing at longer times appears to be a flow process of absorbed polymer at the craze tip.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 1845-1852 
    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: Molecular motion in cured epoxy resin filled with mica flakes was investigated by dynamic mechanical and broad-line nuclear magnetic resonance measurements. Temperature dependences of dynamic modulus and tanδ were determined at 10 Hz for samples containing various amounts of filler. A primary dispersion temperature, T∞, corresponding to the glass transition, shifts to higher temperature with increasing filler volume fraction Vf. The magnitudes of the slope parameters Hr (representing storage modulus E′ data below Tg) decreased with increasing Vf, but Hg (representing E′ data below Tg) remained nearly constant over the whole loading range studied here. NMR line shapes were observed over the temperature range from room temperature to about 200°C for unfilled and filled samples. Each sample showed a distorted line shape in the transition region where major narrowing occurs. The distorted line shape was decomposed into both broad and narrow components by Gaussian analysis. The temperature range where both components can be obtained becomes broader with increasing filler content. The possibility is set forth that the filler immobilizes the chain segments and causes a different distribution of local mobility around the junction point.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 791-798 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of craze initiation has been investigated for unmodified and rubber-modified polystyrenes in n-alcohols. The dependence on time and temperature of the critical strain at which crazes could be detected visually was determined with a Bergen elliptical strain device. Sorption studies were also conducted at room temperature on films exposed to the saturated vapor of n-alcohol. The analysis of crazing data in terms of the Eyring model gave activation energies from 9.4 to 17.4 kcal/mole, increasing with increasing chain length of n-alcohol and increasing rubber content. The activation volume multiplied by a stress concentration factor decreased with increasing rubber content and was nearly independent of the chain length of the n-alcohol. The larger the diffusion coefficient, which we measured by sorption experiments, the smaller was the activation energy for craze initiation. The values of diffusion coefficients, estimated from the experimental data on craze initiation, were found to be comparable with those from the sorption experiments. It was concluded that the rate of craze initiation on exposure to liquids is controlled by the diffusion of the molecules of liquid into polymer.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 3 (1965), S. 2637-2651 
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Viscoelastic properties of unsaturated polyesters were investigated in the glass-rubber transition region in relation to the temperature dependence of specific volume. Polyesters which are homologous with respect to crosslinking density were prepared by using mixtures of succinic and fumaric acid as the dibasic acid component. The temperature dependence of the specific volume was determined by refractive index measurement, the specific refractivity being assumed to be independent of temperature. The temperature dispersion of dynamic viscoelasticity was measured at a constant frequency. Results are summarized as follows. Specific volume and glass temperature are linearly related to the logarithm of crosslinking density. The thermal expansion coefficient and steepness of viscoelastic dispersion decrease with increasing crosslinking density. Fractional free volume and expansion coefficient of free volume, both of which were calculated by WLF equation, are in good agreement with the temperature dependence of specific volume. The results indicate that the effect of crosslinking is largely attributable to the change in amount and distribution of free volume in polymer networks.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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