EVA...how is ethyl vinyl acetate made and is the process environmentally friendly?
Answer:
Unfortunately none of the above actually answered your question. EVA is made by a process called "emulsion polymerization" in which vinyl acetate and ethylene gas (under pressure) are polymerized in water in the presence of a water soluble free radical initiator, usually a persulfate of some kind. A surfactant (a type of detergent) is present in the water, and a latex of EVA particles in water is produced. This latex can be used as is, or the water can be removed and the polymer washed to remove the by-products of polymerization and surfactants. The reaction is exothermic, so pressure, and temperature has to be closely monitored.
Since the solvent of the reaction is water, and the surfactant/initiation system are environmentally benign, this is as environmentally friendly as a chemical process can get.
Hey,
My name is EVA, are you talking to me ?
EVA stands for ethylene-vinyl acetate, and is an addition copolymer of both monomers. "Environmentally friendly" is too subjective to judge.
Ethylene-vinyl acetate (also known as EVA or sometimes simply as "acetate") is the copolymer of ethylene and vinyl acetate.
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 and heat sealing properties and resistance to UV radiation. EVA has little or no odor and is competitive with rubber and vinyl products in many electrical applications.
EVA foam is used as padding in equipment for various sports such as ski boots, hockey, boxing, and mixed martial arts.
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.
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 typically used as a shock absorber in for example tennis shoes.
It is also used in the photovoltaics industry as an encapsulation material for silicon wafers.
EVA is one of the materials popularly known as 'expanded rubber' or 'foam rubber'.
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