etüleenvinüülalkoholi

Ethylene vinyl alcohol, often abbreviated as EVOH, is a copolymer derived from ethylene and vinyl alcohol. It is a thermoplastic resin that is soluble in water in its pure form, but it is typically processed as a solid material. The properties of EVOH can be tailored by adjusting the ratio of ethylene to vinyl alcohol monomers. Higher vinyl alcohol content generally leads to improved barrier properties, particularly against gases.

EVOH is primarily recognized for its exceptional barrier properties against oxygen and other gases. This makes it a valuable material in packaging applications where it is crucial to prevent the ingress of oxygen and the egress of volatile compounds. Its low permeability to oxygen is significantly better than that of many other common plastics.

The main application for EVOH is in multilayer plastic structures. It is often coextruded or laminated with other polymers, such as polyethylene or polypropylene, to create packaging films and containers. In these multilayer structures, EVOH provides the barrier layer, while the other polymers offer mechanical strength, sealability, and processability. Common uses include food packaging to extend shelf life, pharmaceutical packaging, and containers for certain chemicals. Despite its excellent barrier properties, EVOH itself has limited mechanical strength and can be susceptible to moisture, which is why it is almost always used in conjunction with other materials.