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  • 1
    Electronic Resource
    Electronic Resource
    Transient networks in ABA block copolymer-microemulsion systems (1990)
    s.l. : American Chemical Society
    Macromolecules 23 (1990), S. 3347-3352 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00215a022
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Dielectric relaxation and deuteron NMR of water in polyimide films (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 5290-5296 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polyimide films containing up to 3.2 wt. % water (H2 O or D2 O) have been studied by dielectric relaxation (DR) and 2H nuclear magnetic resonance (NMR) spectroscopies. Dielectric loss measurements show the presence of a double peak near 200 K due to water, with two components designated as γ1 and γ2 . The γ2 peak, which appears at the lower temperature, is only present for the interior portion of thick (〉25 μm) films and rapidly decreases as the moisture content decreases. Correspondingly, deuteron NMR measurements show the presence of narrow and broad lines, which are correlated, respectively, with the γ1 and γ2 DR peaks. The spin-spin relaxation time T2, is much longer for the narrow line than for the broad line. The γ1 DR peak and the narrow NMR line are attributed to sites where isolated water molecules are only loosely coupled to the polymer chains. The γ2 and broad NMR lines involve small clusters of water molecules with associated nuclear magnetic dipole-dipole coupling. Additional measurements on polyimides containing methanol and acetic acid absorbents are also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343719
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  • 3
    Electronic Resource
    Electronic Resource
    Recover the phases from intensity data of x-ray diffraction (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 909-911 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For many years, people believed that in conventional x-ray crystallography one can only record the scattering intensities but not the phases. In order to study structures at the atomic scale, one has to use multibeam measurement or to rely on additional knowledge such as bonding length and to fit the intensity data by trial structure models. In this letter, however, we show that the phases are in fact hidden in the intensity data and can be recovered by studying the peak shoulders. To demonstrate, the x-ray diffraction data of aluminum powder were used to recover the phases and to reconstruct the electron density map. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122034
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Immobilization of lipase in composites of gelatin and polystyrene via an emulsion-gel pathway (1992)
    Springer
    Biotechnology techniques 6 (1992), S. 555-560 
    Details
    ISSN: 1573-6784
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A new method for the immobilization of lipase within composites of polystyrene and gelatin is suggested. First, an emulsion of styrene (containing an initiator) in an aqueous solution of gelatin (containing a dispersant) is prepared with mechanical stirring at 50°C. An aqueous solution of lipase is added (at room temperature) under stirring to the gel-like emulsion previously prepared. The polymerization of the gel containing lipase was carried out at room temperature for four days. The activity of the immobilized lipase in the hydrolysis reaction of triacetin was investigated. The activity depends on the content of gelatin within the composite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02447831
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  • 5
    Electronic Resource
    Electronic Resource
    Dielectric properties of novel poly(aryl prehnitimide)s (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 731-736 
    Details
    ISSN: 0887-6266
    Keywords: poly(aryl prehnitimide)s ; bent diimide ; ac impedance ; dielectric constant ; permittivity ; loss tangent ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Six different variants of a new type of polyimide, poly(aryl prehnitimide)s, containing various moisture contents have been studied using dielectric relaxation spectroscopy. Dielectric loss measurements show the presence of a double peak near 200 K (depending on frequency) due to water relaxation. The two peaks have been designated γ1 and γ2. The γ2 peak appears as a shoulder on the γ1 peak at lower temperatures and is very sensitive to moisture content. The γ1 peak is less sensitive to moisture content and is associated with isolated water molecules coupled to the polymer chains. Both of the γ-relaxation peaks were studied in detail to obtain the associated activation energies. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of covalently cross-linked gelatin gels in percolating water-in-oil microemulsions (1990)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 11 (1990), S. 217-222 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1990.030110505
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  • 7
    Electronic Resource
    Electronic Resource
    Moisture-absorption, dielectric relaxation, and thermal conductivity studies of polymer composites (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2259-2265 
    Details
    ISSN: 0887-6266
    Keywords: polymer composite ; moisture-absorption ; dielectric loss ; thermal conductivity ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the search for new packaging materials for the electrical/electronics industry, three types of polymer composites have been studied. Silicone/boron nitride powders, polyurethane/alumina powders, and polyurethane/carbon fibers have all been synthesized to study the moisture-absorption kinetics, thermal conductivities, and the dielectric loss spectra under various levels of humidity. The water uptake data indicate that water molecules are absorbed not only by the polymer matrix, but also by the interfaces introduced by the fillers. For all materials, the dielectric relaxation spectroscopy shows the presence of a peak in the 175-200 K range, which is largely due to absorbed water. The silicone/boron nitride samples absorbed the least amount of moisture. Incorporating this result with the thermal conductivity data of the three types of polymer composites, it is concluded that silicone polymers embedded with boron nitride can best serve as the coating for the electronic devices that require heat dissipation and moisture resistance, in addition to electrical insulation. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2259-2265, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    Blockcopolymers in microemulsions differential heats of solution and shift of the percolation temperature in W/O microemulsions (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 213-220 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solutions of blockcopolymers (POE-b-PI-b-POE) in fluids of interacting aqueous nanodroplets (W/O microemulsions) are studied. The interaction strength between the (pseudo) two components is measured by the shift of the percolation temperature relative to that of the pure microemulsion. A quantitative measure of the interaction, the differential heat of solution, is thermodynamically related to the slopes of the equilibrium temperature of the system with varying monomeric nanodroplet concentration and the experimental percolation line in the presence of copolymer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730125
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