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  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 2205-2210 
    ISSN: 0887-6266
    Keywords: polyarylamine ; corona discharge poling ; waveguide ; optical loss ; modal dispersion ; second harmonic generation ; phase-matching ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The electric field-induced dynamic phase-matching of second harmonic generation (SHG) waveguide was demonstrated by using a main chain polyarylamine. The linear and nonlinear optical properties of this polymer are presented. The optimum phase-matching thickness was controlled by applying an electric field to the polymer waveguide. The effective phase-matching thickness variation induced by poling is about 0.025 μm that is six times larger than full width at the half-maximum (FWHM) of phase-matching thickness in conventional slab waveguide. The efficient phase-matched SHG was observed from a taperless slab wave-guide. The optical loss of poled polymer on glass substrate at 632.8 nm was 2.7 dB/cm. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 615-623 
    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: Crystallization during melt spinning is studied as an example of the nonisothermal crystallization of polymers. The following equation is derived, taking the temperature distribution within a filament into consideration: \documentclass{article}\pagestyle{empty}\begin{document}$$ \kappa \nabla ^2 T = {\rm V} \cdot {\rm grad } \ T - \frac{{\Delta H}}{{C_p }}{\rm V} \cdot {\rm grad } \ X $$\end{document} where T = temperature, X = crystallinity, κ = thermal diffusivity, V = velocity, ΔH = heat of crystallization, and Cp = specific heat at constant pressure. The assumptions and the procedure for a numerical calculation of crystallinity and temperature within a running filament are described, and some results of calculation are illustrated. The results are compared with those obtained by a simpler calculation in which the radial temperature distribution is neglected. The simpler method proved useful in connection with x-ray measurements.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1077-1091 
    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 changes in temperature and crystallinity of polymer during nonisothermal crystallization were theoretically analyzed assuming a cooling condition under which heat transfer occurs at a rate proportional to the difference in temperature between polymer and the environment. When a plateau appears in the temperature change during crystallization, crystallization temperature can be predicted by a simple method. This method gives nearly the same value as that obtained by successive calculations of temperature and crystallinity throughout the whole process. In addition, a graphic method is presented to predict crystallization temperature. By using the plateau temperature observed in melt-spinning experiments, the crystallization rate under molecular orientation is evaluated. Furthermore, a method applicable to estimating the ultimate crystallinity is proposed. A rough estimation of the increase in the rate of crystallization under molecular orientation was carried out for very high-speed spinning of poly(ethylene terephthalate).
    Additional Material: 8 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 907-914 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric properties of vinyl acetate and methyl methacrylate oligomers having chemically different end groups were compared. Dielectric measurements were carried out over the frequency range between 23 and 3 MHz and the temperature range between +50 and -50°C. The static dielectric constants of these oligomers are between 10 and 20. The relaxations were analyzed with the Havriliak-Negami equation. The dielectric properties depend on the chain end groups on the oligomers. The distribution of relaxation times of the vinyl acetate oligomers was wider than that of poly(vinyl acetate). It was concluded that two cooperative motions, that of the principal chain and that of the chain and that of the chain end group, take part in the dielectric relaxation of these short chain molecules.
    Additional Material: 6 Ill.
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  • 5
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Unter Verwendung von Schwefelsäure-Sulfat-Komplex-Katalysatoren konnte in nichtpolaren Lösungsmitteln bei Zimmertemperatur ein isotaktischer Polyvinylisobutyläther erhalten werden. Als Sulfate wurden Al-, Mg- und Cr-Sulfat verwandt. Die erhaltenen Polymeren besaßen eine größere Stereospezifität als die Polymeren die bei -78°C mit Hilfe von BF3·O(C2H5)2 hergestellt worden waren. Mit steigender Polymerisationstemperatur fiel die Stereospezifität der Polymeren nicht ab, sondern stieg eher noch schwach an.
    Notes: Using H2SO4 metal sulfate complex catalysts, in non-polar solvents isotactic polyvinyl isobutyl ether was obtained at room temperature. Al, Mg, and Cr sulfates were used as metal sulfates. These polymers had a higher regularity than that of polymers which were polymerized by BF3 · Et2O at -78°C. In the polymerization by these complex catalysts, the stereoregularity of the resultant polymer did not change or rather increased slightly with the raise of temperature.
    Additional Material: 11 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 1789-1796 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric properties of low-molecular-weight propylene glycols HO—[CH(CH3)CH2O]n—H (n = 3, 4, 5) were investigated to clarify the effect of chain length on the dielectric properties. The measurement of dielectric constant and dielectric loss was carried out over the frequency range 30 Hz to 30 MHz at temperatures of -20 to -65°C. The static dielectric constants of these glycols are between 10 and 30, slightly smaller than values for the corresponding ethylene glycols of the same degree of polymerization. All of the Cole-Cole arcs, even that for pentapropylene glycol, can be represented by the empirical Davidson-Cole equation. The dielectric properties of homologous propylene glycols are compared with those for the ethylene glycols and are discussed in terms of the effects of chain length and intermolecular hydrogen bonds.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 3991-4001 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Terpolymerization of tetrafluoroethylene (TFE) with propylene (P) and isobutylene (iB) by γ radiation at temperatures of -78 to 40°C, a dose rate of 5 × 104-5 × 105 rad/hr, and an iB/P molar ratio of 40/10-5/45 in the monomer mixture was carried out. Alternating copolymers of TFE and α-olefins, that is, P and iB, were formed at various monomer compositions. No crystalline structure was observed in the terpolymer obtained below an iB/P molar ratio of 15/35 in the monomer mixture but a partly crystalline order increased with the amounts of iB in terpolymer. The crystal lattice of the TFE-iB copolymer was affected by the introduction of P. The dose rate dependencies of the polymerization rate and inherent viscosity were 0.8 and -0.2, respectively. The activation energy of polymerization was 2.4 kcal/mole, and the relative reactivity ratio of iB and P for a TFE radical chain end was estimated as 4.50 by the treatment of the free propagating mechanism.
    Additional Material: 10 Ill.
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