EVA - Thermoplastic polymers, elastomers and additives

EVA is a semicrystalline material, (thermoplastic elastomers), whose characteristics derive mainly from the comonomer of vinyl acetate. This comonomer prevents the crystallization of the polymer chain and thus reduces the crystallinity of the material; this means that EVA, in comparison with LDPE, becomes more flexible and transparent as the amount of vinyl acetate contained increases. As the strength of the material decreases, its melting range is also reduced: the EVA melting temperature is therefore lower than that of the LDPE. Vinyl comonomer acetate is also responsible for the characteristic odor of EVA, which copolymers vaguely resemble dell'aceto. The EVA due to its polar character, which absorb small amounts of moisture. The water absorption increases with the increase of VA copolymers. They are permeable to gases and vapor. The permeability is inversely proportional to the fraction of crystalline material in olimer. EVA copolymers with a vinyl acetate content of 10 to 30% have characteristics similar to elastomers and plasticized PVC with a content of 30 to 40% plasticizer. The Eva compared to PVC has a better resistance to low temperatures without migration of plasticizer so that a permanent elasticity, a greater resistance to bending and better resistance to chemicals, better electrical insulation properties, unlike the Gas barrier properties are lower such as resistance to light and abrasion. Compared with the EVA elastomer copolymers have a better resistance to ozone (depending on the type of elastomer) is working as the thermoplastic is not vulcanizing necessary against having a lower high temperature resistance when subjected to stresses, and less elasticity.

We have at your disposal the widest range of EVA grades, with different hardness and stabilization and acetate content.

The properties of EVA copolymers are mainly determined by the vinyl acetate content and the degree of fluidity. An increase in VA content increases the density, transparency and flexibility of the material, while reducing the melting point and hardness . The ethylene-vinyl acetate copolymer (EVA) is a very elastic material that can be sintered to form a porous material similar to rubber, but with excellent strength. It is three times more flexible than low density polyethylene (LDPE), showing a tensile elongation of 750% with a maximum melting temperature of 96 ° C.

The introduction of a polar comonomer inside polyethylene chains affects the electrical properties of the final polymer: the coefficient of dielectric loss and relative dielectric constant of EVA copolymers depend on the VA content. EVA copolymers, despite being characterized by insulating properties inferior to homopolymer (LDPE), find application in the cable industry thanks to its good resistance to stress corrosion, easy crosslinking and good flexibility. In addition, the high capacity of EVA copolymers to incorporate fillers, such as carbon black, make them very used for the manufacture of semiconductor compounds.

Ethylene vinyl acetate (EVA) is not dangerous by ingestion, unless you eat an object made of EVA that is large enough to cause suffocation or other problems, in which case it would pose the same hazards as any other plastic object. Inhalation does not pose a threat unless you actually work in a processing plant. If the material is processed at high temperatures (200 ° C and above), it can emit fumes that could act as irritants. This situation, however, should only be a concern in the manufacturing process, not during residential use. EVA copolymers due to their polar nature, they absorb small amounts of moisture. The absorption of water increases with the increase in VA. Resistance to surfactants increases as the VA content decreases in degree of fluidity. EVA copolymers are permeable to gases and vapors. EVA copolymers can be damaged by atmospheric agents and in particular by ultraviolet radiation from sunlight. The best solvent for poly (ethylene-co-vinyl acetate (EVA)) to dilute the EVA (solid form) that is normally applied in the petroleum industry in order to inhibit wax is cyclohexane.

Hot melt adhesives, hot glue sticks, are generally based on EVA, generally with additives such as wax and resin. EVA is also used as an additive adhesion improvement in plastic wrap. EVA is also used in biomedical engineering applications as a drug delivery device. The polymer is dissolved in an organic solvent (for example, methylene chloride). Powder and filler medications (typically an inert sugar) are added to the liquid solution and mixed rapidly to obtain a homogeneous mixture. The drug-polymer-charge mixture is then cast to a mold at -80 degrees and lyophilized in the solid state. These devices are used in the search for the administration of drugs to slowly release a compound over time. Although the polymer is not biodegradable within the body, it is quite inert and causes little or no implant reaction. EVA is one of the materials popularly known as 'rubber foam' or 'rubber foam'. EVA is used as filler in sports equipment such as ski boots, hockey, boxing, mixed martial arts, boots, wakeboard boots, teats, handles, flexible tubes, turntable mats, beer tubes, vacuum cleaners, cleaning hoses. Water skiing and fishing rods. It is usually used as a shock absorber for sports shoes, for example. In addition, thanks to its buoyancy, EVA has made its way into non-traditional products, such as floating glasses. It is also used in the photovoltaic sector as a material for the encapsulation of silicon cells for the production of photovoltaic modules. EVA slippers and sandals are very popular nowadays for their properties such as lightweight, easy to mold, odorless finish, glossy, and cheaper compared to natural rubber. In fishing poles, used to build handles at the end of the cane. EVA emulsions are acetate (PVAc), polyvinyl copolymers based on vinyl acetate (VAM) of vinyl acetate plastized internally with ethylene (VAE). PVAc copolymers are adhesives used in packaging, textiles, ligatures for bonding plastic films, metal surfaces, coated paper. In addition, orthotics, fire-safe cigarettes, surfboards and skimboard traction pads, and for the production of some artificial flowers. It is also used as an additive that improves adhesion in plastic wrap, a cold flow improver for diesel fuel and a separator in HEPA filters. EVA is easily cut from the leaves and adapted to the shape. It is also used to make thermoplastic mouthguards that soften in boiling water for a specific adaptation of the user. This copolymer resin can be used in adhesives, sealants and coatings. It is the basis of many hot melt adhesives when mixed with a petroleum wax and a resin tackifier.