Premium
A spin‐probing study of non‐magnetic ionomers: Cu 2+ ‐containing polyethylene/methacrylic acid copolymer neutralized with Zn 2+
Author(s) -
Yamauchi Jun,
Narita Hidehiro,
Kutsumizu Shoichi,
Yano Shinichi
Publication year - 1995
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1995.021961205
Subject(s) - ionomer , differential scanning calorimetry , polyethylene , ionic bonding , polymer chemistry , polymer , copolymer , materials science , methacrylic acid , analytical chemistry (journal) , chemistry , ion , thermodynamics , organic chemistry , composite material , physics
A spin‐probing technique was first applied to a study of a non‐magnetic ionomer, polyethylene/methacrylic acid copolymer neutralized with Zn 2+ (E‐MAA‐Zn); 2 mol‐% Cu 2+ ions were incorporated in replacement of Zn 2+ , and its ESR spectra were observed in detail at various temperatures in order to obtain physico‐chemical properties of E‐MAA‐Zn, especially its structural changes. We found no significant influence of the 2 mol‐% Cu 2+ ‐incorporation upon the properties of the Zn 2+ ionomer by differential scanning calorimetry (DSC), which showed two endothermic peaks, (1) an irreversible one at lower temperature which is associated with the ionic aggregate phase in the ionomer, (2) a reversible one at higher temperature with considerable thermal hysteresis which is due to melting of the polymer main chains. ESR hyperfine coupling constants ( A ∥ and A ⊥ ) of Cu 2+ showed no sign of structural changes of the polymer around the phase‐transition temperatures, whereas ESR g ‐values ( g ∥ and g ⊥ ) of Cu 2+ proved the onset of the softening of the polymers to be attributable to polymer melting. The latter slope‐changes in the temperature dependences were reversible, although with considerable thermal hysteresis. These findings are compatible with the DSC data. As for the irreversibility regarding the endotherm at lower temperature, broad ESR hyperfine components recovered gradually, indicating an order‐disorder nature of the ionic aggregate phase transition.