Eisaku Hirasawa

Transition of ionic clusters in ionomers

Differential scanning calorimetric and thermal expansion measurements were made for the complex Zn(II) salts of ethylene-methacrylic acid copolymer with 1, 3-bis-aminomethylcyclohexane. One transition of the ionic clusters in the polymer matrix was found near 325 K as a peak on the DSC and thermal expansion curves. The transition exhibited a thermal hysteresis which was explained by the relaxational destruction/reformation of a structure in the inside of ionic clusters.

Dielectric properties of complex salts of Zn(ii) salts of ethylene-methacrylic acid copolymer with 1,3-bisamino-methylcyclohexane

Abstract Dielectric relaxations in complex salts of Zn(II) salts of ethylene-methacrylic acid copolymer (E-MAA), MAA content 5.4 mol%, with 1,3-bisaminomethylcyclohexane (BAC) were studied in detail. In E-MAA and the Zn(II) salts, β′ and γ relaxations were observed around 320 and 190 K at 1 kHz, which are attributed to micro-Brownian molecular motion of long segments and local molecular motion of short segments. When BAC is added to the two polymers, the β′ relaxation was replaced by α and β relaxations. The α and β relaxations were related to a glass-rubber transition of ionic clusters and to molecular motion of isolated salts and carboxylic acid not incorporated into the ionic clusters, respectively. From the above results, it was concluded that BAC strongly promotes the formation of ionic clusters.

EXAFS studies on Zn(II) complexes with 1,3-bis(aminomethyl)cyclohexane of ethylene-methacrylic acid copolymer

Abstract Extended X-ray absorption fine structure (EXAFS) experiments were performed at 25 and 105°C for Zn(II) salts of ethylene-methacrylic acid (5.4 mol%) copolymer and their complexes with 1,3-bis(amino-methyl)cyclohexane (BAC) (EMAA-Zn-BAC). The zinc carboxylate in EMAA-Zn-BAC systems was in a four-fold coordination at room temperature. The ZnO distance increased with increasing BAC content, and became smaller at 105°C than at room temperature for EMAA-0.60Zn and EMAA-0.60Zn-0.40BAC but scarcely changed with temperature for EMAA-0.60Zn-0.97BAC. The fluctuation factor (σ) was larger at 105°C than at room temperature for all the samples, due to thermal vibration. In this paper, it is pointed out that these EXAFS results support the presence of an order-disorder transition in ionic clusters.

Structure and Molecular Motion in Complex Salts of Ethylene — Methacrylic Acid Copolymer With 1,3-Bis-Aminomethylcyclohexane and/or Zinc(II)

Formation of ionic clusters and molecular motion in the complex salts of Zn(II) salts of ethylene - methacrylic acid copolymer(E- MAA, content of MAA is 5.4 mol%) with 1,3-bis-aminomethylcyclohexane(BAC ) have been studied by small angle X-ray scattering and dielectric measurements. As content of BAC is increased, the size and concentration of ionic clusters increase and the a dielectric relaxation associated with a glass-rubber transition of ionic clusters appears around 350 K. It was concluded that BAC facilitates the formation of ionic clusters in the Zn(II) salts of E-MAA.