Mechanical and dynamic mechanical properties of the zinc neutralized salts of poly (ethylene co-acrylic acid) (PEA) and its blends with epoxidized natural rubber (ENR) have been studied. Improvement in tensile strength, hardness (Shore-A), and a reduction in elongation at break and tension set with the increase in degree of neutralization of the blend constituents corroborate the existence of hard and rigid domains of ionic clusters in the non-hydrocarbon and flexible backbone chain. The occurrence of a new relaxation peak due to ionic aggregates and the disappearance of the crystalline transition indicates the formation of a new ionic cluster phase in the matrix. A shift in the glass transition temperature towards higher temperature supports the existence of ionic crosslinks in the polymer matrix.