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.
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