Ethylene vinyl alcohol (EVOH) is a formal copolymer of ethylene and vinyl alcohol. EVOH copolymer is defined by the mole % ethylene content: lower ethylene content grades have higher barrier properties; higher ethylene content grades have lower temperatures for extrusion. The proportion of both monomer type is important factors in determining properties to prevent in and out Oxygen transmission very well under dry conditions. But it’s so sensitive to moisture when moisture increase is cause decrease properties to prevent Oxygen transmission rapidly.