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Friday, July 26, 2013

What Is EVA Foam?

Ethylene vinyl acetate (also known as EVA) is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene.
It is a polymer that approaches elastomeric materials in softness and flexibility, yet can be processed like other thermoplastics. The material has good clarity and gloss, barrier properties, low-temperature toughness, stress-crack resistance, hot-melt adhesive water proof properties, and resistance to UV radiation. EVA has little or no odor and is competitive with rubber and vinyl products in many electrical applications.

Applications

Hot melt adhesives, hot glue sticks, top of the line soccer cleats, are usually made from EVA, usually with additives like wax and resin. EVA is also used as a clinginess-enhancing additive in plastic wraps.
EVA is also used in biomedical engineering applications as a drug delivery device. The polymer is dissolved in an organic solvent (e.g., dichloromethane). Powdered drug and filler (typically an inert sugar) are added to the liquid solution and rapidly mixed to obtain a homogeneous mixture. The drug-filler-polymer mixture is then cast into a mold at −80 °C and freeze dried until solid. These devices are used in drug delivery research to slowly release a compound. While the polymer is not biodegradable within the body, it is quite inert and causes little or no reaction following implantation.
EVA is one of the materials popularly known as expanded rubber or foam rubber. EVA foam is used as padding in equipment for various sports such as ski boots, bicycle saddles, hockey pads, boxing and mixed martial arts gloves and helmets, wakeboard boots, waterski boots, fishing rods and fishing reel handles. It is typically used as a shock absorber in sports shoes, for example. It is used for the manufacture of floats for commercial fishing gear such as purse seine (seine fishing) and gillnets. In addition, because of its buoyancy, EVA has made its way into non-traditional products such as floating eyewear. It is also used in the photovoltaics industry as an encapsulation material for silicon cells in the manufacture of photovoltaic modules. EVA slippers and sandals are currently very popular because of their properties like light weight, easy to mold, odorless, glossy finish, and cheaper compared to natural rubber. In fishing rods, it is used to construct handles on the rod-butt end. EVA can be used as a substitute for cork in many applications.
EVA emulsions are polyvinyl acetate (PVAc) copolymers based on vinyl acetate (VAM) internally plastized with vinyl acetate ethylene (VAE). PVAc copolymer are adhesives used in packaging, textile, bookbinding for bonding plastic films, metal surfaces, coated paper, as redispersible powder in plasters and cement renders
Vinyl acetate ethylene copolymer(VAE), is also used in coatings formulation of good quality interior water-borne paints at 53% Primary dispersant
Hydrolysis of EVA gives ethylene vinyl alcohol (EVOH) copolymer.

Other uses

EVA is used in the manufacture of the Adidas Jabulani football. EVA is used in orthotics, fire safe cigarettes (FSC), surfboard and skimboard traction pads, and for the manufacturing of some artificial flowers. It is used as a cold flow improver for diesel fuel and a separater in HEPA filters. EVA can easily be cut from sheets and molded to shape. It is also used to make thermoplastic mouthguards that soften in boiling water for a user specific fit. It is also used for impregnation of leather. Additional uses are in the making of nicotine transdermal patches since the copolymer binds well with other agents to form gel like substances. EVA is also sometimes used for making body bags.

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