Ethylene vinyl alcohol - high barrier polymers for food packaging

One of the two most important high barrier polymers used for food packaging applications is ethylene vinyl alcohol (EVOH). EVOH is a flexible, crystal clear, and glossy thermoplastic copolymer with excellent flex-crack resistance, and very high resistance to hydrocarbons, oils and organic solvents.

EVOH semi-crystalline is a copolymer of ethylene and vinyl alcohol known to be an excellent barrier against oxygen, dioxide and aroma permeability, which makes it particularly suited for packaging food, drugs, cosmetics, and other perishable products.

It is especially important for refrigerated and shelf-stable foods where oxygen deteriorates the quality of packaged products and reduces their shelf life. The increased oxygen barrier property helps food items remain fresh and prevent premature decomposition.

The copolymer composition (i.e., relative amounts of ethylene and vinyl alcohol) affects properties of EVOH copolymers such as gas barrier, mechanical properties, water vapor transmission, etc., and hence influences EVOH processing and end use applications.

EVOH has a far better oxygen barrier than PVDC (polyvinylidene chloride) when dry, that is, at 0% relative humidity (RH).

However, EVOH loses its good gas barrier properties when exposed to moisture. In this case, EVOH is often used in a multilayer co-extruded film structure with materials such as HDPE, PP and PET, all of which have superior moisture barrier properties. As a result, EVOH is often referred to as a multilayer barrier technology.
Ethylene vinyl alcohol - high barrier polymers for food packaging