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  • 1
    ISSN: 1435-1536
    Schlagwort(e): Ethylene-acrylic acid copolymer ; Transition metal salts ; Dynamic mechanical properties ; Ion-cluster ; Degree of neutralization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Dynamic mechanical properties of ethylene-acrylic acid copolymer (mole% ofAA is 9.3) neutralized with copper(II), manganese(II) and nickel(II) acetates were measured in a temperature range of −150 to 80 °C at 3.5, 11, 35 and 110 Hz. Theβ′ andγ relaxations are observed around 30 and −140 δC, respectively, which are attributed to a micro-Brownian molecular motion of segments and a local molecular motion of short segments, respectively. In theβ′ relaxation, the relaxation temperature increased with increasing degree of neutralization,x, and the peak height decreased, which were independent on the species of counter ions. Theβ relaxation which is ascribed to molecular motion of rather short segments between ion-clusters was observed at high ion concentrations. The effects ofx on theβ′ andβ relaxations were different from those of the preceding dielectric results. This discrepancy between the mechanical and the dielectric results can be explained by the assumption that the segments responsible for the mechanical relaxations are different of those for the dielectric relaxation. In theγ relaxation, the relaxation temperature and the peak height were almost independent ofx and the species of counter ions. The relation between the molecular motion and the structure of the transition metal salts (complex structure and formation of ion-clusters) was understood well by examining the mechanical and dielectrical results together.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 262 (1984), S. 788-792 
    ISSN: 1435-1536
    Schlagwort(e): Liquid crystal formation ; Poly(γ-benzyl L-glutamate) ; Aggregation ; Phase separation ; Solvent effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Solvent effects on the phase separation of poly(γ-benzyl L-glutamate) to liquid crystal and isotropic solution have been observed in various helicogenic solvents. The temperature-composition phase diagrams have been determined for each solution. The critical concentrations,ν 2 * , at which the phase separation occours have been compared in various solvents. In dimethylformamide in which the polymer is molecularly dispersed, the observedν 2 * value has agreed with that calculated by Flory's theory. In some solvents in which the polymer aggregates in a head-to-tail mode such as chloroform, the observedν 2 * values have been considerably small. It is assumed that the polymer aggregates behave as longer particles than the original particles. In dioxane in which the polymer aggregates highly both in a head-to-tail and a side-by-side modes, theν 2 * value has been a little larger than that in chloroform. In this case the relationship between the aggregation and the liquid crystal formation is so complicated that further investigation is necessary. In aromatic solvents such asm-cresol that dissolves the polymer almost molecularly, theν 2 * is smaller than that in dimethylformamide. Therefore, the intermolecular interactions between the phenyl groups in the side groups of the polymer and those in solvent molecules must be considered.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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