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| Ethylene-vinyl acetate | |
|---|---|
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| IUPAC name |
but-3-enoic acid; ethene
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| Identifiers | |
| CAS number | 24937-78-8 |
| PubChem | 32742 |
| SMILES |
C=C.C=CCC(=O)O
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| Hazards | |
| MSDS | MSDS |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
| Infobox references | |
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, 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., methylene chloride). 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 degrees and freeze dried until solid. These devices are used in drug delivery research to slowly release a compound over time. 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, hockey, boxing, mixed martial arts, wakeboard boots, waterski boots, and fishing rods. It is typically used as a shock absorber in sports shoes, for example. 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 nowadays very popular because of its 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.
Use
EVA is used in orthotics, fire safe cigarettes, surfboard and skimboard traction pads, and for the manufacturing of some artificial flowers. It is also used as a clinginess-enhancing additive in plastic wraps, a cold flow improver for diesel fuel and a separater in HEPA filters. EVA is easily 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.
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