Ethylene Vinyl Alcohol

Brief Overview

Ethylene vinyl alcohol (EVOH) is a formal copolymer of ethylene and vinyl alcohol. EVOH copolymer is defined by the mole percentage ethylene content: lower ethylene content grades have higher barrier properties; higher ethylene content grades have lower temperatures for extrusion.

Manufacturing Process

Manufacturing of EVOH is considered costly, not many manufacturing companies exist. The production of EVOH is a two-step process that consists of polymerization and saponification. First, ethylene and vinyl acetate are polymerized using an initiator/activator complex. Second, the ethylene-vinyl acetate copolymer (EVAc) is saponified to ethylene vinyl alcohol copolymer. 

Automotive Industry

In this industry EVOH is used in fuel tank production. It is light which reduces the weight of vehicles. Moreover, it prevents fuel permeation.

Packaging

Due to its strong barrier against oxygen and gas, food packaging manufacturers use EVOH in their packaging structure to extend the shelf life of food products (mostly packaging films).

Medicine 

EVOH is used in a liquid embolic system in interventional radiology. Dissolved in dimethyl sulfoxide and mixed with a radiopaque substance it creates liquid embolizing blood vessels.