When do I need a barrier layer like EVOH?

EVOH (ethylene vinyl alcohol) is one of the best oxygen barrier materials available in flexible packaging, but it is also more expensive and moisture-sensitive than the polyethylene layers around it, so it only gets specified when oxygen transmission is actually the thing limiting shelf life or product quality. If a product oxidizes, goes rancid, loses aroma, or degrades when exposed to ambient oxygen, that is a strong signal a barrier structure is worth the added cost.

EVOH is never run as a standalone layer. It is sandwiched inside a co-extruded structure between polyethylene layers, using a tie layer to bond it to the surrounding resins, because EVOH does not adhere well to PE on its own and loses much of its barrier performance if it gets wet. That is why barrier structures are engineered as a full multi-layer system, not just an additive.

If you are not sure whether your product needs barrier film, tell us the shelf-life problem you are trying to solve. We can tell you whether EVOH is the right tool or whether a simpler structure will do the job at lower cost.