Question: What copolymer of ethylene and vinyl acetate can nanofibers be made of?
Context: The conservation and restoration of vinyl discs refers to the preventive measures taken to defend against damage and slow degradation, and to maintain fidelity of singles, 12" singles, EP, LP in 45 or 33⅓ rpm disc recordings.  LPs are most often in the 12” format, although very early vinyl recordings were 10”.  Vinyl LP preservation is generally considered separate from conservation, which refers to the repair and stabilization of individual discs.  Commonly practiced in major sound archives and research libraries that house large collections of audio recordings, it is also frequently followed by audiophiles and home record collectors.  Because vinyl—a virtually unbreakable light plastic made up of polyvinyl chloride acetate copolymer, or PVC—is considered the most stable of analog recording media, it is seen as less a concern for deterioration than earlier sound recordings made from more fragile materials such as acetate, vulcanite, or shellac.  This hardly means that vinyl recordings are infallible, however, and research—both expert and evidential—has shown that the way in which discs are handled and cared for can have a profound effect on their longevity.  Though some 45s (7”s) are also made from vinyl, many of them are actually polystyrene—a more fragile medium that is prone to fracturing from internal stress.  Still, many of the recommendations for the care of vinyl LPs can be applied to 45s. Vinyl acetate is an organic compound with the formula CHCOCHCH.  A colorless liquid with a pungent odor, it is the precursor to polyvinyl acetate, an important polymer in industry.  Unlike many other acetate esters, the odor of vinyl acetate is thoroughly disagreeable and is not used to any substantial degree as an odorant. Wacker Chemie AG is a worldwide operating company in the chemical business, founded 1914.  The company is controlled by the Wacker family holding more than 50 percent of the shares.  The corporation is operating more than 25 production sites in Europe, Asia, and the Americas.  The product range includes silicone rubbers, polymer products like ethylene vinyl acetate redispersible polymer powder, chemical materials, polysilicon and wafers for semiconductor industry.  The company sells its products in more than 100 countries.  As of 31 December 2015, 16,972 employees have been with Wacker.  Corporate annual sales in 2015 were about 5,3 billion Euros, up 10% compared to 2014. Polyketones are a family of high-performance thermoplastic polymers.  The polar ketone groups in the polymer backbone of these materials gives rise to a strong attraction between polymer chains, which increases the material's melting point (255 °C for copolymer (carbon monoxide ethylene), 220 °C for terpolymer (carbon monoxide, ethylene, propylene).  Trade names include Carilon, Karilon, Akrotek, and Schulaketon.  Such materials also tend to resist solvents and have good mechanical properties.  Unlike many other engineering plastics, aliphatic polyketones such as Shell Chemicals' Carilon are relatively easy to synthesize and can be derived from inexpensive monomers. Carilon is made with a palladium(II) catalyst from ethylene and carbon monoxide.  A small fraction of the ethylene is generally replaced with propylene to reduce the melting point somewhat.  Shell Chemical commercially launched Carilon thermoplastic polymer in the U.S.in 1996, but discontinued it in 2000.  SRI International offers Carilon thermoplastic polymers.  Hyosung announced that they would launch production in 2015 Ethylene-vinyl acetate (EVA), also known as poly (ethylene-vinyl acetate) (PEVA), is the copolymer of ethylene and vinyl acetate.  The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene. Solutia Inc. is a global manufacturer of performance materials and specialty chemicals including polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), and thermoplastic polyurethane (TPU) interlayers for laminated glass, aftermarket window films, protective barrier and conductive films, and rubber processing chemicals, used in architectural, automotive, alternative energy, electronic devices, consumer and industrial applications.  The company was formed on September 1, 1997, as a divestiture of the Monsanto Company chemical business.  In July 2012, the company was acquired by Eastman Chemical Company. EPDM rubber (ethylene propylene diene monomer (M-class) rubber), a type of synthetic rubber, is an elastomer characterized by a wide range of applications.  The "M" refers to its classification in ASTM standard D-1418; the "M" class includes rubbers having a saturated chain of the polymethylene type.  Dienes currently used in the manufacture of EPDM rubbers are dicyclopentadiene (DCPD), ethylidene norbornene (ENB), and vinyl norbornene (VNB).  EPDM rubber is closely related to ethylene propylene rubber: ethylene propylene rubber is a copolymer of ethylene and propylene, whereas EPDM rubber is a terpolymer of ethylene, propylene, and a diene-component. Nanofibers are fibers with diameters in the nanometer range.  Nanofibers can be generated from different polymers and hence have different physical properties and application potentials.  Examples of natural polymers include collagen, cellulose, silk fibroin, keratin, gelatin and polysaccharides such as chitosan and alginate.  Examples of synthetic polymers include poly(lactic acid) (PLA), polycaprolactone (PCL), polyurethane (PU), poly(lactic-co-glycolic acid) (PLGA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and poly(ethylene-co-vinylacetate) (PEVA).  Polymer chains are connected via covalent bonds.  The diameters of nanofibers depend on the type of polymer used and the method of production.  All polymer nanofibers are unique for their large surface area-to-volume ratio, high porosity, appreciable mechanical strength, and flexibility in functionalization compared to their microfiber counterparts. Ethylene vinyl alcohol (EVOH) is a formal copolymer of ethylene and vinyl alcohol.  Because the latter monomer mainly exists as its tautomer acetaldehyde, the copolymer is prepared by polymerization of ethylene and vinyl acetate to give the ethylene vinyl acetate (EVA) copolymer followed by hydrolysis.  EVOH copolymer is defined by the mole % ethylene content: lower ethylene content grades have higher barrier properties; higher ethylene content grades have lower temperatures for extrusion. Polyvinyl chloride acetate (PVCA) is a thermoplastic copolymer of vinyl chloride and vinyl acetate.  It is used in the manufacture of electrical insulation, of protective coverings (including garments), and of credit cards and swipe cards.
Answer: Ethylene-vinyl acetate