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  • 1
    Publication Date: 1990-02-01
    Print ISSN: 0722-3277
    Electronic ISSN: 1431-584X
    Topics: Physics
    Published by Springer
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  • 2
    Publication Date: 1970-11-01
    Print ISSN: 0372-820X
    Electronic ISSN: 1435-1536
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 79 (1990), S. 101-104 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The127I and133Cs NMR spectra of polycrystalline CsIO4, a material of potential interest for transformation of laser irradiation, have been measured in the temperature range 170–440 K and the line shape has been analyzed taking into account first and second order quadrupole interactions and chemical shift anisotropy. Quadrupole coupling constants and asymmetry parameters have been determined as a function of temperature.127I and133Cs data consistently show two phase transitions in the ranges 243–300 K and 420–440 K with a temperature hysteresis for the first transition and a range for coexistence of two phases. The time evolution of the NMR signal suggests the existence of piezomagnetism, which was believed to exist only in crystals with a magnetic structure.
    Type of Medium: Electronic Resource
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  • 4
    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: Summary A monomer unit of polyethyleneterephthalate consists of two four-spin systems, namely the four-protons of the benzene ring and the four protons of the C2H4-group. TheSchroedinger equation for these four-spin systems is solved for rigid arrangement as well as for rotation of the systems. The interaction of each of the four spin systems with the protons of the environment is taken into account by broadening the single lines toGaussian curves. It was possible to fit the calculated curves to the measured curves. By this fitting, the broadening parameters and the amounts of rotating groups could be determined as a function of temperature.
    Notes: Zusammenfassung Eine Monomereinheit von Polyäthylenterephthalat besteht aus zwei Vier-Spinsystemen, nämlich aus den vier Protonen des Benzolringes und den vier Protonen der C2H4-Gruppe. DieSchrödinger-Gleichung für die beiden Vier-Spinsysteme wurde gelöst, sowohl für den Fall, daß diese starr angeordnet sind, als auch für den Fall, daß sie rotieren. Die Wechselwirkung eines jeden Vier-Spinsystems mit der Umgebung wurde durch eine Verbreiterung der Einzellinien zuGaußkurven berücksichtigt. Die berechneten Kurven konnten an die gemessenen angepaßt werden. Dabei wurden die Verbreiterungsparameter und die Anteile der Gruppen, die jeweils rotieren, in Abhängigkeit von der Temperatur bestimmt.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 147 (1971), S. 41-51 
    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: The NMR-spectra of crystallized polyethyleneterephthalate were measured before and after swelling in deuterated acetone as function of the temperature. Each spectrum was divided into a broad and a narrow component. It is shown that owing to swelling the glass transition region becomes broader and the transition temperature is lowered. The line width of the narrow component is increased by swelling, which is attributed to an increase of the tension of the chains in the noncrystalline regions. The second moment of the broad component is decreased by swelling, from which it is concluded that the swelling agent penetrates also into the crystals.A sample crystallized by swelling was also investigated. With this sample the narrow component shows an unusually small line width. This is explained by a comparatively large amount of swelling agent present in the sample as well as by a very small tension of the chains in the noncrystalline regions. Both effects are a consequence of the special mechanism which occurs during crystallization by swelling.
    Notes: Die Kernresonanzspektren isotherm kristallisierter Proben von Polyäthylenterephthalat wurden vor und nach der Quellung in deuteriertem Aceton als Funktion der Temperatur gemessen. Anschließend wurde jedes Spektrum in eine breite und eine schmale Komponente zerlegt. Es zeigt sich, daß durch die Quellung der Einfrierbereich verbreitert und die Einfriertemperatur erniedrigt wird. Diese Erniedrigung ist von den Kristallisationsbedingungen unabhängig. Die Linienbreite der schmalen Komponente wird durch die Quellung leicht erhöht, was für eine Zunahme der Kettenverspannung in den nichtkristallinen Bereichen spricht. Das zweite Moment der breiten Komponente wird durch die Quellung erniedrigt. Daraus wird geschlossen, daß das Quellmittel auch in die Kristallite eindringt.Des weiteren wurde eine Probe unmittelbar durch Quellung kristallisiert. Bei dieser Probe beobachtet man eine besonders kleine Linienbreite der schmalen Komponente. Dies wird durch den höheren Quellmittelgehalt der Probe sowie durch eine relativ geringe Verspannung der Ketten in den nichtkristallinen Bereichen erklärt. Beides ist eine Folge des besonderen Mechanismus der Quellungskristallisation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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