Ethylene vinyl alcohol copolymer, often shortened to EVOH, comes from the copolymerization of ethylene and vinyl alcohol units. People often see this material in the form of flakes, powder, pearls, and sometimes as a solid or solution, depending on how it gets processed. The copolymer forms as a translucent resin, sometimes coming off as clear or slightly milky in appearance. Industrial use leans heavily on EVOH’s gas barrier properties, setting it apart from many other plastics. This material shows up in food packaging, pharmaceutical films, and automotive tanks, largely for its ability to block oxygen and other gases. EVOH’s structure, a repeating sequence of ethylene and vinyl alcohol, allows for these strong barriers, but also impacts its processability and compatibility with other plastics.
Structurally, EVOH consists of two repeating monomers — ethylene and vinyl alcohol. Manufacturers vary the ratio, usually in the range of 27 to 48 mole percent ethylene, to hit performance targets. The chemical formula commonly appears as (C2H4)m–(C2H4O)n. This sequence ties into features like melt point, gas transmission rate, and solubility. The copolymer’s density falls between 1.12 and 1.17 g/cm3. In solid form, EVOH feels tough, yet lightweight. The copolymer can be shipped as a raw material in pellets or flakes to meet different manufacturing specs. Some versions dissolve in water or alcohol when heated, which lets people use EVOH for coatings or specialty solutions. The crystal structure formed in the copolymer creates the tough oxygen barrier prized in many industries.
Across the industry, companies offer EVOH in a range of melt flow indexes and ethylene content to match various processing methods. Most often, it lands in packaging or as an intermediate material. Food wrappers, retortable pouches, and pharmaceutical blister packs draw on EVOH’s gas barrier ability, which comes straight from its chemical makeup and fine-tuned density. The copolymer comes in granular or powder form, sometimes as small pearls, giving manufacturers flexibility – injection molding, blown film extrusion, and co-extrusion lines can handle this material with small process adjustments. Sheet and film thickness can range from a few microns to thicker profiles for specialty uses. EVOH-based coatings and solutions also play a role, sometimes used as a liquid barrier when dissolved and sprayed or painted onto surfaces.
Trade regulations identify Ethylene Vinyl Alcohol Copolymer using the HS Code 39053000, which covers copolymers of ethylene with other monomers. This code streamlines customs checks and international transport. In terms of safety, EVOH does not fit the profile of a hazardous chemical according to current OSHA and GHS standards, but it deserves careful handling. Grinding or high-heat processing releases fine dust and vapors, so facilities use standard ventilations and dust collection protocols. The raw pellet, flake, or powder do not carry harmful properties for ordinary skin contact, but inhaling dust should be prevented as with any fine polymer. Molten EVOH can cause burns, so heat-resistant gloves and eye protection matter during hot-melt operations. Disposal usually follows local solid waste rules, since EVOH will not break down quickly in landfill, unless blended with more degradable materials or sent to approved recycling.
Thanks to its sharply tuned vapor and gas barrier, EVOH took over many traditional uses of aluminum foil or multi-layer laminates that relied on metals. EVOH films do not crack after repeated flexing, so food remains fresh for weeks or months in flexible packaging. My own connection to EVOH came from working in a packaging plant, where the decision to switch to EVOH-layered films had two clear benefits. First, these films flushed out the problem of spoilage in long-haul transport; second, they made the recycling process a little less tricky than metal-lined laminates. Cost tends to run a bit higher than basic polyethylene, but food companies keep reaching for EVOH, because wasted product hits profit far harder than the small increase in material expense. EVOH has also shown up in the fuel system industry – the barrier keeps gasoline and ethanol from evaporating out of plastic tanks, chipping away at pollution and safety concerns.
As good as EVOH can be for specific uses, challenges keep popping up. Copolymer resins like EVOH can struggle with moisture sensitivity; the gas barrier drops if the film sits in high humidity for long. People in the packaging world look for solutions – maybe lamination with polyolefins (like as part of a PE/EVOH/PE sandwich) or adding extra layers to seal out water. EVOH does not break down in the natural world, leading to questions about long-term disposal. Recycling EVOH is possible, but it needs careful separation from other polymers. Some companies head toward chemical recycling, aiming to reclaim the monomers for new production. Switches to renewable feedstocks for ethylene also deserve mention, since that could drop EVOH’s carbon footprint. Until then, designers and engineers keep fine-tuning the copolymer ratios, processing aids, and blends, searching for solutions that hit all the marks – less waste, stronger barrier, safer handling, and a smaller impact on the environment.
