EVOH delivers oxygen barrier performance that no commodity polyethylene or polypropylene resin can approach, making it the standard choice when a product's shelf life depends on excluding oxygen rather than just moisture. It is never used as a standalone film; it is always a thin core layer within a coextruded structure, typically a single-digit percentage of total structure thickness, because even a small amount delivers most of the barrier benefit at a manageable cost.
EVOH's defining limitation is moisture sensitivity: its oxygen barrier performance degrades as the resin absorbs ambient moisture, which is why it is always sandwiched between polyolefin layers that protect it from direct moisture exposure on both sides. Because EVOH does not bond well to polyethylene or polypropylene on its own, structures require a tie layer to adhere it to the surrounding layers. Getting the tie layer chemistry and the EVOH layer thickness right is a core part of barrier structure design, not an afterthought.