Ethylene Vinyl Acetate (EVA)

Ethylene Vinyl Acetate (EVA) Ethylene vinyl acetate (EVA), also known as polyethylene-vinyl acetate (PEVA), is a copolymer of ethylene and vinyl acetate. The weight percentage of vinyl acetate typically ranges from 10% to 40%, with the remainder being ethylene. There are three different types of EVA copolymers that differ in vinyl acetate (VA) content and material applications. EVA copolymer based on a low VA content (approximately up to 4%) is known as vinyl acetate-modified polyethylene. EVA is a copolymer and is processed as a thermoplastic material, much like low-density polyethylene. It possesses some properties of low-density polyethylene, but with enhanced gloss, softness and flexibility. EVA copolymer based on moderate VA content (approximately 4% to 30%) is called thermoplastic ethylene-vinyl acetate copolymer and is a thermoplastic elastomer material. It is not vulcanised, but possesses certain properties at high levels comparable to rubber or plasticised polyvinyl chloride. Both filled and unfilled EVA materials have good low-temperature properties and are durable. EVA copolymer based on high VA content (over 60%) is called ethylene vinyl acetate rubber. Ethylene vinyl acetate copolymer does not have an acidic odour unless it is thermally degraded. However, high temperatures and the presence of certain additives (for example, high quantities of clay) cause the formation of a sharp, acetic acid odour as a result of thermal degradation of the ethylene vinyl acetate copolymer. EVA can be cross-linked using peroxides and radiation methods. The polymerisation technique also alters the VA content in EVA. EVA demonstrates better blending properties with NR and SBR for better ozone resistance, and its main characteristic is excellent resistance to oxygen, ozone and light. However, EVA exhibits poor resistance to tearing and abrasion. EVA is an elastomeric polymer that produces rubber-like materials with softness and flexibility. The material has good clarity and gloss, low-temperature toughness, stress-crack resistance, hot melt adhesive waterproof properties and resistance to UV radiation.

Applications

EVA is primarily used in cable applications, medical extrusions, flooring materials, coatings and gaskets. Hot melt adhesives (such as hot glue sticks) and first-class football studs are also typically made from EVA using additives such as wax and resin. EVA is also used as an adhesive-enhancing additive in plastic films. Modelling foam sheets are made from EVA and are commonly used in foam stamping production. EVA is also used in biomedical engineering applications as a drug delivery device. The polymer is dissolved in an organic solvent (such as dichloromethane). Powdered drug and filler (usually inert sugar) are added to the liquid solution and rapidly mixed to obtain a homogeneous mixture. The drug-filler-polymer mixture is then poured into a mould at -80°C and freeze-dried until solidified. These devices are used in drug research to slowly release a compound. The polymer is not biodegraded in the body, but is highly inert and causes little or no reaction following implantation. Different hardness levels can be achieved in EVA depending on the composition during the manufacturing process. Since EVA does not regain its shape after continuous compression, it is important to be careful about the hardness level. A softer EVA will have poor abrasion resistance compared to a harder one and will therefore provide a short service life in the outer layer, but greater comfort. EVA is popularly known as one of the materials known as expanded rubber or foam rubber. EVA foam is used as filling material in various sports equipment such as ski boots, bicycle saddles, hockey pads, boxing and mixed martial arts gloves and helmets, water skiing boots, water skiing boots, fishing rods and fishing reel handles. In sports shoes, they are commonly used as shock absorbers. EVA is also used in commercial fishing equipment such as purse seine and trawl nets for the manufacture of floats. It is also used in the photovoltaic industry as an encapsulation material for crystalline silicon solar cells in the production of photovoltaic modules. EVA slippers and sandals are popular because they are lightweight, easy to mould and odourless, as well as glossy and cheaper than natural rubber. EVA can also be used as a substitute for cork in many applications. EVA copolymers are adhesives used in packaging, textiles, binding, adhesion of plastic films, metal surfaces and coated paper, and as redispersible powders in cement plasters. In recent years, EVA foam has become popular in cosplay communities because it provides ease of work, durability and comfort compared to traditional plastic-based costumes. Flower-making foam is a thin layer made of flexible EVA and is used by craftspeople in artificial flower production. These foams are supplied as raw sheets and can be cut into desired petal shapes. These petals are then assembled and shaped by ironing to create artificial flowers. EVA is also used in quality interior water-based paint coating formulations containing 53% primary dispersant. Sources https://www.sciencedirect.com/topics/engineering/ethylenevinyl-acetate https://web.archive.org/web/20210427125524/https://www.hoehnplastics.com/pdf/sds-101-ethylene-vinyl-acetate.pdf https://www.findsourcing.com/articles/components/eva---ethylene-vinly-acetate