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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 170 (1952), S. 125-125 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Type of Medium: Electronic Resource
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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 35 (2000), S. 4439-4447 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ethylene was copolymerized with 10-undecen-1- ol in the presence of four different metallocene catalyst systems. The copolymers were characterized by differential scanning calorimeter (DSC) and by dynamic mechanical analysis (DMA). It was demonstrated that properties of the catalysts used affected the crystallization behaviour of the copolymers because the catalysts exhibited differences in conversions of the polar comonomer. The step crystallization technique using DSC provided useful information about the differences in comonomer incorporation in the chain. The formation of multiple peaks, based on differences in ethylene sequence length, is much weaker for the copolymers produced with a non- bridged metallocene, than for polymers produced with bridged catalysts. A study of the crystallization rates in nonisothermal experiments exhibited a small decrease in crystallization temperatures with increasing branching. The Hoffman-Weeks extrapolation of melting point vs crystallization temperature gave reasonable results for silylene-bridged copolymers. In DMA, study was made of the storage modulus as an indicator of stiffness and loss tangent as a measure of the effect of branching on the β-relaxations. The DMA measurements indicated a slight increase in the flexural modulus, or stiffness values, of the copolymers relative to the corresponding homopolymers. The damping curves did not show any peaks in the β-relaxation range, which indicates that the amount of short branching in the copolymers is negligible.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 49 (1976), S. 1-8 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Einwirkung des Metallgehalts in Poly(m-phenylen-bis-1,3,4-oxadiazol) und Cu(II)-, Ni(II)- und Co(II)-Polymerchelaten entsprechender aromatischer Polyhydrazide auf die Gleichstrom- und Co(II)-Polymerchelaten entsprechender aromatischer Polyhydrazide auf die Gleichstrom- und Wechselstromleitfähigkeit wurde bei einer Meßfrequenz von 1 kHz und bei Temperaturen von 293 K bis 573 K untersucht. Die elektrische Leitfähigkeit war gering. In der Leitfähigkeitskurve zeigten alle Polymeren einen Wendepunkt, der eine Veränderung im Leitfähigkeitsmechanismus anzeigt. Cu(II) zeigte eine starke Einwirkung auf die Gleichstromleitfähigkeit, während Ni(II) und Co(II) keinen Einfluß hatten. Ni(II) und Co(II) verändern im Gegensatz zu Cu(II) andererseits die dielektrische Umwandlungstemperatur.
    Notes: The influence of metal content of some metal chelates of an aromatic polyhydrazide on the DC and AC conductivity was studied in the temperature range of 293 to 573 K at a constant frequence of 1 kHz. The compounds studied were poly(m-phenylene-bis-1,3,4-oxadiazole) and Cu(II)-, Ni(II)- and Co(II)-chelates of the corresponding aromatic polyhydrazide. The conductivity is rather low and all compounds show a break point in the conductivity curve indicating a change in the conductivity mechanism. Cu(II)-ions seem to have the highest influence on the DC conductivity, while Ni(II)- and Co(II)-ions change the dielectric transition temperatures more than Cu(II).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 57 (1977), S. 169-173 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die elektrische Leitfähigkeit und die elektrischen Eigenschaften von Poly(azo-1,4-phenylen-vinylen-1,4-phenylen) wurden untersucht. Die thermische Aktivierungsenergie der Gleichstromleitfähigkeit wurde mit der Aktivierungsenergie der dielektrischen Relaxation verglichen. Die dielektrische Aktivierungsenergie wurde aus der Temperaturabhängigkeit von ε′ und ε″ bei einer festen Frequenz ermittelt. Es konnte gezeigt werden, daß die Aktivierungsenergie aus der Fläche von ε″ über der reziproken Temperatur bestimmt werden kann.Die aus der Gleichstromleitfähigkeit erhaltene Aktivierungsenergie Ea=1.50eV ist ungefähr gleich der dielektrischen Aktivierungsenergie 〈1/H〉a v-1=1,62 eV.Der Leitungsmechanismus in Poly(azo-1,4-phenylen-vinylen-1,4-phenylen) wird diskutiert.
    Notes: The electrical conductivity and dielectric properties of poly(azo-1,4-phenylene-vinylene-1,4-phenylene) were examined. The thermal activation energy of the direct current (DC) conductivity was compared with the activation energy of the relaxation process, evaluated from the area and the width of the curve of the dielectric loss factor against reciprocal temperature at constant frequency.The activation energy Ea=1.50 eV of the intrinsic DC conductivity was found to be roughly equal to the dielectric activation energy [1/H]a v-1=1,62 eV.The conduction mechanism in poly(azo-1,4-phenylene-vinylene-1,4-phenylene) is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 747-754 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The electrical conductivity of a series of semiconducting polyazophenylenes was studied as a function of temperature and molecular weight in the temperature range 293-493°K and for molecular weights between 9500 and 62800. The compounds studied included poly-2,4-diminotoluene and poly-2,5-diaminotoluene. The temperature dependence of conductivity obeys the exponential law σ = σ0 exp {-Ea/kT}. All of the compounds studied show a break in the conductivity curve at a temperature of about 380°K with the slope of the curve greater at temperatures above 380°K. The activation energies Ea determined from the higher slopes are in the range 0.63-0.89 eV, and the corresponding σ0 values are in the range 10-4-10° (ohm-cm)-1. Both Ea and σ0 show a tendency to increase with increasing molecular weight such that the compensation law was valid. Activation energies and σ0 values determined from the (smaller) slope below the temperature of the break point showed a tendency to decrease with successive measurements on new samples. This indicates some kind of orientation effect, and conclusions concerning the properties of the material on basis of results below the break point are therefore difficult.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1547-1553 
    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 a series of semiconducting polyazophenylenes were studied as a function of temperature and molecular weight in the temperature range 293-600°K and for molecular weights between 5,100 and 62,800 at a constant frequency of 1 kHz. The compounds studied included poly-2,4-diaminotoluene, poly-2,4-diaminoanisole, and poly-2,5-diaminotoluene. The dielectric properties are presented in the usual way in terms of a complex dielectric constant ε* = ε′ - jε″. Activation energies of relaxation processes were evaluated from the areas and widths of the dielectric loss factor, ε″, against reciprocal temperature at constant frequency. The dielectric activation energies were found to be roughly equal to the activation energies from the DC conductivity. This indicates that the conduction mechanism is based on rotational movements of molecules or parts of molecules.
    Additional Material: 6 Ill.
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  • 8
    Publication Date: 2006-10-28
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 9
    Publication Date: 2008-09-01
    Print ISSN: 1359-6462
    Electronic ISSN: 1872-8456
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Elsevier
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  • 10
    Publication Date: 1978-04-01
    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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