What copolymer of ethylene and vinyl acetate can nanofibers be made of?
Nanofiber 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.
Conservation and restoration of vinyl discs 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.