Ionomers are ethylene-(metha)acrylic acid copolymers that carboxyl acids are partially neutralized by metal ions such as Zn++, Na+, K+, Mg++.
The ionic interaction between metal ions and carboxyl acid induce a kind of cross-linking effect and ionomers work as thermoplastic elastomers.
The ionic bonds are dissociated by heating and melt flow of ionomers is increased for easy extrusion process. But by cooling, ionic bonds are foamed again to make cross-linking.
Metal Ion : Zn2+ ,Na+, K+, Mg2+
Ionomers are composed of crystalline and amorphous domains and these domains are partially cross-linked that show thermoplastic elastomeric behavior.