Ethylene vinyl acetate - a substance belonging to the class of esters, is obtained by copolymerization of ethylene and vinyl acetate monomer .
| Ethylene vinyl acetate | |
|---|---|
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| Are common | |
| Abbreviations | EVA |
| Traditional names | Ethylene Vinyl Acetate Copolymer |
| Chem. formula | C₆H₁₀O₂ |
| Physical properties | |
| Density | 0.931 g / cm³ |
| Thermal properties | |
| T. melt. | depends on the percentage of vinyl acetate: VA = 28% +65 ° C [1] VA = 8% +96 ° C [2] |
| Thermal conductivity | 0.35 W / (mK) |
| Classification | |
| Reg. CAS number | |
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Vinyl acetate units are randomly distributed in the macromolecule of the copolymer. The vinyl acetate content determines the mechanical properties of the copolymer , as well as its type ( elastomer or thermoplastic ). Most often, an EVA with 10-50% m vinyl acetate content is used. At 100% vinyl acetate , polyvinyl acetate (PVAC) is obtained. With a high vinyl acetate content, ethylene vinyl acetate acquires high resistance to oils , solvents , ozone and high temperature. Low acetate copolymers have properties similar to those of low density polyethylene . In addition, the properties of ethylene vinyl acetate copolymers depend on side chain formation and molecular weight.
Ethylene vinyl acetate is a lightweight and resilient material with good cushioning properties, surpasses polyethylene in transparency and elasticity at low temperatures, and has increased adhesion to various materials.
Processing method and scope
- extrusion : films, sheets, hoses , cable sheath, car mats .;
- injection molding: shoe soles, toys , isomats;
- production of hot melt adhesives (so-called hot melt adhesives ).
EVA copolymer is used to prepare compounds with other polymers, for example, rubber , PVC or polyethylene , as well as mixtures with fillers and additives.
This material in the form of an aqueous dispersion has found wide application as a film former in aqueous dispersion paints. A specially dried aqueous dispersion of ethylene vinyl acetate is a redispersible powder, widely used in the production of dry building mixtures.
Operating temperature range: from −80 ° C to +55 ° C (briefly up to +70 ° C).