Structure and molecular motion of ethylene-acrylic acid copolymers neutralized with manganese (II) and nickel (II) acetates

The existence of ion-clusters in ethylene-acrylic acid copolymers (mole% of acrylic acid is 9.3) neutralized with manganese(II) and nickel(II) acetates, respectively, was studied by dielectric measurements in the temperature range of −180 to 80 °C at several frequencies between 30 Hz and 100 kHz. Theβ′ relaxation due to a micro-Brownian molecular motion aboveT g and theγ relaxation due to a local molecular motion belowT g were observed. Variation in the magnitude and the relaxation temperature of the two relaxations with degree of neutralization by manganese/nickel acetate suggest the formation of ion-clusters in the higher degrees of neutralization above a value between 3.3 and 14% for the Mn(II) salts and above about 14% for the Ni(II) salts. Furthermore, this formation of ion-clusters was evidenced by electron spin resonance and small angle X-ray scattering studies. The ESR spectra for the Mn(II) salts exhibited six peaks at 14% of degree of neutralization and one peak at 62%. This indicates the existence of ion-clusters at 62%. The small angle X-ray scatterings suggested the existence of ion-clusters of diameter of about 27 Å for the Mn(II) salts and 19–23 A for the Ni(II) salts, at the high degrees of neutralization above 14%.