EVOH Full Form:
Ethylene-Vinyl Alcohol Copolymer
What is EVOH?
A formal copolymer of ethylene and vinyl alcohol is called ethylene vinyl alcohol (EVOH). The copolymer is made by polymerizing ethylene and vinyl acetate to generate the ethylene vinyl acetate (EVA) copolymer, followed by hydrolysis, because the latter monomer primarily exists as its tautomer acetaldehyde. The mole% ethylene content of an EVOH copolymer determines its barrier qualities. Grades with lower ethylene content offer higher barrier properties, while grades with higher ethylene content require lower extrusion temperatures.
EVOH is said to have superior barrier qualities when compared to other frequently used films. The potential of EVOH to serve as a gas barrier is lost when it is exposed to moisture. Due to its effective moisture barrier qualities, EVOH is frequently utilized in multilayer co-extruded film constructions with materials including HDPE, PP, and PET.
How is EVOH made?
Blow-molded rigid containers and multilayer food packaging typically use the barrier resin ethylene vinyl alcohol copolymer (EVOH). The two-step procedure that creates EVOH consists of two steps: polymerization and saponification (the chemical reaction or process that makes soap). Ethylene and vinyl acetate are initially polymerized using an initiator/activator combination. By saponifying the ethylene-vinyl acetate copolymer, the ethylene vinyl alcohol copolymer is produced (EVAc).
EVOH is particularly well suited for packaging food, medications, cosmetics, and other perishable goods because it provides some of the best barrier resistance to gases like oxygen, nitrogen, and carbon dioxide. The EVOH plastic is commonly used to make different product packaging and much more. Some of the product packaging examples are mentioned below-