Ethylene-Methacrylic Acid Copolymers lonomers

Zinc neutralized, Ethylene-Methacrylic acid Copolymer lonomer (E-MAA, Zn) Zinc carboxylate, Carboxylic acid Low reactivity with amine but good polar interaction of Zn with amide and amine groups (interfacial complexation) Tg, hardness limit low temperature toughness Good solvent resistance... 

RS 5 lonomer ethylene-methacrylic acid copolymer, partially neutralized by alkali. 

Ethylene-methacrylic acid copolymers, partially neu-tralized with sodum or anc (lonomer) The most important applications are for food packaging as films or sheets. They adhere to nylon in coextrusion, and they heat seal well. 

Neutralization of EAA or a similar copolymer, for example EMAA (ethylene methacrylic acid), with cations such as Na Zn Li produces a material that has better transparency, toughness, and higher melt strength than the unneutralized copolymer. These materials are called lonomers because they combine covalent and ionic bonds in the polymer chain. The structure of an ionomer of the ethylene sodium acrylate type is ... 

Neutralization of ethylene copolymers containing up to 5%-10% acrylic or methacrylic acid copolymer with a metal salt such as the acetate or oxide of zinc, magnesium, and barium yields products referred to as ionomers. (Commercial products may contain univalent as well as divalent metal salts.) lonomers are marked by Du Pont under the trade name Surlyn. These have interesting properties compared with the nonionized copolymer. Introduction of ions causes disordering of the semicrystalline structure, which makes the polymer transparent. lonomers act like reversibly cross-linked thermoplastics as a result of microphase separation between ionic metal carboxylate and nonpolar hydrocarbon segments. The... 

Table 2.5 Interfacial Tensions between Polymer Melt Pairs Including Compatibilizing Agents. MAH-PP Maleic Anhydride Grafted Polypropylene SEES Hydrogenated Triblock Copolymer of Styrene and Butadiene MAH-g-SEBS Maleic Anhydride Grafted SEES PEMA-Zn Poly(ethylene-co-methacrylic Acid) lonomer Neutralized by Zinc.

Some physical properties of polyethylene ionomers are compared with those of polyethylene and the acid copolymer, poly(ethylene-co-methacrylic acid) in Table 5.15. lonomer is generally tougher and, as shown in Table 5.15, relative to the acid copolymer, its tensile strength is increased by 27—53% and its stiffness is nearly tripled. 

Ethylene ionomers consist of copolymers of ethylene and an organic acid, such as methacrylic acid, the acid moieties of vhich have been neutrali2ed to form a metal salt. The metal salts from neighboring chains tend to form clusters, such as the one shown schematically in Fig. 18.3. The net result is the overall structure shown in Fig. 18.2 g), in which the ionic clusters form weak crosslinks between adjacent chains. lonomers also contain short and long chain branches, which are similar to those foimd in low density polyethylene. 

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