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Surlyn® is a family of ethylene methacrylic acid (E/MAA) copolymers, in which part of the methacrylic acid is neutralized with metal ions such as zinc (Zn) or sodium (Na). The resulting polymer structure has three regions: amorphous polymer, crystalline polymer, and ionic clusters.
 | Surlyn® polymer structure shows 3 features:
amorphous regions,
crystalline regions,
and ionic clusters. |
Surlyn® resins can be used in adhesion promotion, toughening and polymer compatibilizing, with functionality influenced by the following factors:
- Comonomer content,
- Acid neutralization level (ion clusters),
- Type of metal ion (sodium or zinc), and
- Termonomer content.
The termonomer is an acrylate with low glass transition temperature (Tg) and is optional. The higher the termonomer content, the lower the glass transition temperature and the better the toughening functionality. Grades that contain termonomers are Surlyn® 9020, 9320 and 8020, 8320.
The type of metal ion will determine largely together with the content of acid groups the compatibility with the engineering polymer that has to be modified. As a rule of thumb, sodium will provide better compatibility with polyesters, while zinc will be better when modifying polyamides.
The ions, which bring some kind of crosslinking to the polymer, provide the following features and benefits:
- Superior abrasion resistance
- Transparency
- Scratch and scuff resistance
- Thermoformability
- Low temperature impact resistance
- Compatibility/adhesion to metal, polyamides, polyesters and polyolefins
Among the applications of ionomers and the acid copolymers that they are based on are the following:
- Promoting adhesion to metals
- PA adhesion promotion
- PA toughening
- PET crystallization aid
- PA/PE compatibilizing
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