DIELECTRIC RELAXATIONS OF ETHYLENE IONOMERS

Dielectric relaxation studies were performed for the alkali (Na, K), alkaline earth (Mg, Ca), and transition [Cu(II), Mn(II), Co(II)] metal salts of the ethylene-methacrylic acid (5.4 mol%) copolymer (EMAA), and for the transition metal complexes with 1,3-bis(aminomethyl)cyclohexane (BAC) of EMAA. It was pointed out that the dielectric relaxations of the ethylene ionomers are sensitive to the formation of ionic clusters. When the ionic clusters are formed, the beta' relaxation related to a glass-rubber transition above T(g) was depressed and there appeared two relaxations, the alpha-relaxation above T(i), due to a micro-Brownian molecular motion of long segments containing the salt groups incorporated into the ionic clusters, and the beta-relaxation below T(i), due to a molecular motion of short segments containing the isolated salt groups. From this relationship between dielectric relaxations and the formation of ionic clusters, it was concluded that the Na, K, Ca, Mg, and Co(II) salts of EMAA form the ionic clusters at higher neutralization above about 30%, but the Cu(II) and Mn(II) salts do not form clusters even at 60% neutralization. In the transition-metal complexes with BAC, the formation of ionic clusters was drastically promoted by the addition of BAC.