Ionomer

Ionomers are thermoplastics, which first came on the market in 1964. They are marketed under the trade name Nafion (DuPont).

Ionomers are obtained by copolymerization of a non-polar to a polar monomer. The polar bonds are pushing back the crystallization and lead to an " ionic crosslinking ".

Compared to conventional thermoplastics ionomers have the advantage that both secondary valence forces and ionic bonds are effective in them. These ionic bonds are particularly strong and give the fabric its characteristic properties. Moreover Ionoplasten can serve as electrolytes, in contrast to most other plastic materials. Despite the ionic bonds are ionomers real thermoplastics because they melt at 290-330 ° C. The melting process, however, is already connected to the degradation of the macromolecules. In this case, contaminants can arise, but in any case the ionomer loses some of its properties.

Properties

  • High strength and abrasion resistance
  • High impact and notched impact strength
  • High transparency
  • High ionic conductivity
  • No electrical conductivity
  • Good stress cracking resistance
  • Resistant to acids, alkalis, grease, oils and solvents
  • Not resistant to oxidizing acids, alcohols, aromatic and chlorinated hydrocarbons
  • The weather resistance is similar to polyolefins

Processing

It can be processed by injection molding, extrusion, blow molding or thermoforming. But this must have the functional group which imparts to the product, the ion conductivity, still be masked. If the ionomer by a sulfonic acid group ( -SO3H ) are ion- conducting, then the polymer is extruded into its sulfonyl ( - SO 2 F ). The final shape -SO3H can not be melt processed due to the ionic interaction forces. After the molding process, the functional group reacts with a strong base (NaOH or KOH) to SO 3 Na - or - SO3K. By subsequent action of a strong acid, it is converted to -SO3H.

  • Archetype temperature: about 200-300 ° C
  • Forming temperature: about 150 ° C

Another way of preparing ionomer membranes is to produce a dispersion of about 5-20 wt - % SO3H - ionomer and water-alcohol mixtures. By the use of casting liquid surface occur, from which the solvent evaporates. What remains thin membranes (20-50 microns) in - SO3H form. Taken in porous materials can enhance the mechanical strength and dimensional stability.

Applications

  • Mercury-free chlor-alkali electrolysis for the production of chlorine and chloride- free sodium hydroxide,
  • Electrolyte membranes for polymer electrolyte fuel cells or lithium - polymer batteries,
  • Membranes for humidification or dehumidification of fluid flows,
  • Solid catalyst for acid-catalyzed chemical reactions
  • As a cladding layer in some golf balls, for example of Titleist
  • Thermoplastic
  • Copolymer
  • Electric Technical Material
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