Dynamic mechanical properties of ethylene-acrylic acid copolymers neutralized with copper(II), manganese(II) and nickel(II) acetates

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.