The Effects of Metal Cation Types on Zero Shear Viscosities for Ethylene-co-Methacrylic Ionomer Melts

Abstract

The effects of ion aggregates on zero shear viscosities η₀ for ethylene-co-methacrylic ionomer melts were investigated. Rapid increasing of η₀ for Zn ionomers was shown in high neutralization degree, however, the rapid increase was not observed in all range of neutralization degree for Na ionomers. These results indicate that the formation of ion aggregates strongly affects η₀ only for Zn ionomers. We expect that acid cation exchange, in the case of Na ionomers, cancels effect of ion aggregates on η₀. On the other hand, formation of ion aggregates affects on damping functions for both cases of Na and Zn ionomers. In the case of Zn ionomers, the value of η₀ in high neutralization degree(>40%) deviated from linear regime. This neutralization degree well corresponds to the onset of strong strain dependence of h(γ). We hence consider that measurement of neutralization dependence of η₀ is one of the ways to detect existence of ion aggregates in EMAA-Zn ionomer melts.