Ethylene-vinyl acetate copolymer films

Ethylene vinyl acetate copolymers have a wide variety of industrial uses. Properties of ethylene vinyl acetate copolymer films in terms of oxygen and moisture transfer rate are related... 

Japan Kokai 50-144776, "Saponified Ethylene-Vinyl Acetate Copolymer Films," assigned to Toyobo, 1975. 

Figure 6. Coefficients of friction (p) as a function of UV preirradiation time for ethylene-vinyl acetate copolymer films surface-grafted with poly(N,N- dimethy lacry lamide).

IR SPECTROSCOPIC ANALYSIS OF JONOL IN POLYETHYLENE AND ETHYLENE-VINYL ACETATE COPOLYMER FILMS... 

In the infrared spectra of ethylene-vinyl acetate copolymer films, the ratio of the absorbances of the vinyl acetate C-O stretching vibration at 1020 cm and the ethylene CH2 rocking vibration at 720 cm may be employed as a measure of the composition. Infrared analysis of a number of ethylene-vinyl acetate copolymers of known composition produced the results listed in Table 6.3. The infrared spectrum of a sample of poly(ethylene-co-vinyl acetate) of unknown composition... 

Ethylene vinyl acetate copolymer (EVA) forms a soft, tacky film with good water-vapor barrier but very poor gas-barrier properties. It is widely used as a low temperature initiation and broad-range, heat-sealing medium. The film also serves for lamination to other substrates for heat-sealing purposes. 

A further class of ethylene-vinyl acetate copolymer exists where the vinyl acetate content is of the order of 3 mole %. These materials are best considered as a modification of low-density polyethylene, where the low-cost comonomer introduces additional irregularity into the structure, reducing crystallinity and increasing flexibility, softness and, in the case of film, surface gloss. They have extensive clearance as non-toxic materials. 

Several authors have discussed the ion exchange potentials and membrane properties of grafted cellulose [135,136]. Radiation grafting of anionic and cationic monomers to impart ion exchange properties to polymer films and other structures is rather promising. Thus, grafting of acrylamide and acrylic acid onto polyethylene, polyethylene/ethylene vinyl acetate copolymer as a blend [98], and waste rubber powder [137,138], allows... 

Chattopadhyay, S., Chaki, T.K., Bhowmick, A.K., Gao, G.J.P., and Bandyopadhyay, S., Structural characterization of electron-beam crosslinked thermoplastic elastomeric films from blends of polyethylene and ethylene-vinyl acetate copolymers, J. Appl. Polym. Sci., 81, 1936, 2001. 

The monomers used to make an addition polymer need not be identical. When two or more different monomers are polymerized into the same chain, the product is a copolymer. For instance, we routinely copolymerize ethylene with small percentages of other monomers such as a-olefins (e.g., 1-butene and 1-hexene) and vinyl acetate. We call the products of these reactions linear low density polyethylenes and ethylene-vinyl acetate copolymer, respectively. We encounter these copolymers in such diverse applications as cling film, food storage containers, natural gas distribution pipes, and shoe insoles. 

Figure 69 ATR-FTIR spectrum of the heat seal surface of the good white film (top), the heat seal surface of the bad white film (middle), and the library spectrum of an ethylene/ vinyl acetate copolymer (bottom). 

Ethylene-vinyl acetate copolymers is used in making soft clear films for food packaging. 

Copolymers of ethylene (E) or propylene (P) with acrylic acid (AA) or methacrylic acid (MA) were obtained from SP2 (USA) and used as received (EAA, PAA, PEAA, PMA). Copolymers of ethylene and vinyl alcohol (EVOH) were prepared by hydrolysis (NaOH 0,5M in methanol, reflux, 48 h), of commercial ethylene-vinyl acetate copolymers (EVA, Elf-Atochem) containing 5, 9, 14, and 18 w% of acetate. Hydroperoxides of EPDM based on 5-ethylidene-2-norbornene (0.7 mol Kg 1, Exxon) and polyoctenamer (Vestenamer, VEST, Hiils) resulted from a reaction of polymer films with singlet oxygen. 

A new approach was proposed for making effective helmets which could replace the former British army steel helmet. Essentially the new helmet used modified phenolic resins reinforced with nylon, and the crown cap inside was thermoformed from polyethylene. Formerly the crown cap was attached to the steel by rivets—not an appropriate method for fixing polyethylene to reinforced plastics. Instead a method was developed with a hot-melt adhesive based on ethylene-vinyl acetate copolymers cast as film on release paper. For assembly, the cast film is cut in advance to match the intricate shape required and activated by heat to bond under light pressure subsequently, a further heat activation is employed to fix the crown cap in place (Figure 52 illustrates this). 

Ethylene vinyl acetate copolymers are stable under normal conditions and should be stored in a cool, dry place. Films of ethylene vinyl acetate copolymers should be stored at 0-30°C and less than 75% relative humidity. 

To obtain a higher effidency of photocrossiinking and to improve technological properties of prepared films (smoothness of the surface, transparoic ), 3 to 5% of ethylene-vinyl acetate copolymer having about 12% of vinyl acetate groups ate added [90], Increase of the molecular mass of the added copolymer leads to the increase of insoluble gel which indicates that this copolymer incorporates into the polyethylene network. The decrease or increase of vinyl acetate content in the cx>polymer below/ above an optimum value always reduces the effidency of photoo-osdinldng. 

Many substrates, including paper, paperboard, cellulose film, fireboard, metal foils, or transparent films are coated with resins by direct extrusion. The resins most commonly used are the polyolefins, such as polyethylene, polypropylene, ionomer, and ethylene-vinyl acetate copolymers. Nylon, PVC, and polyester are used for a lesser extent. Often combinations of these resins and substrates are used to provide a multiplayer structure. [A related technique, called extrusion laminating, involves two or more substrates, such as paper and aluminum foil, combined by using a plastic film, (e.g., polyethylene) as the adhesive and as a moisture barrier.] Coatings are applied in thicknesses of about 0.2-15 nuls, the common average being 0.5-2 mils, and the substrates range in thickness fi om 0.5 to more than 24 mils. 

Polyethylene films for agricultural applications need to have high strength and elasticity, resistance to wind forces, and a long service life. They are mostly produced from low density PE combined with linear, low density PE and ethylene-vinyl acetate copolymer. 

Cellulose acetate phthalate film-former, enteric pharmaceuticals Hydroxypropyl methylcellulose phthalate film-former, explosives Dibutyl phthalate film-former, fixing lotions PVP/VA/vinyl propionate copolymer VA/crotonates/vinyl propionate copolymer film-former, flexible hoses Ethylene/methyl acrylate copolymer film-former, floor finishes Ethylene/acrylic acid/vinyl acetate copolymer film-former, flooring compounds Acrylamides copolymer film-former, food... 

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