Polymers ethylene vinyl acetate copolymer

Poly(esters) and rubbers Poly(alkenes) and rubbers Cellulosic polymers, ethylene-vinyl acetate copolymers, poly(alkenes), PVC, rubbers, and poly(styrene) Cellulosic polymers, poly(esters), poly(alkenes), polyurethanes, PVC, rubbers, and poly(styrene)... 

Cellulosic polymers, ethylene-vinyl acetate copolymers, poly(alkenes), PVC, rubbers, and poly(styrene)... 

PVC adhesives—metal polymer Ethylene-vinyl acetate copolymer, Japan 40 1979 Mitsubishi Chemical... 

Polyaniline-montmorillonite nanocomposites were prepared without surface modification of montmorillonite [42]. The polymer nanocomposite was significantly more thermally stable when compared to the pure polymer. Ethylene-vinyl acetate copolymer-clay nanocomposites apparently thermally degrade by a different mechanism than the pure polymer [43]. These observations are consistent with the above thesis. 

This type of adhesive is generally useful in the temperature range where the material is either leathery or mbbery, ie, between the glass-transition temperature and the melt temperature. Hot-melt adhesives are based on thermoplastic polymers that may be compounded or uncompounded ethylene—vinyl acetate copolymers, paraffin waxes, polypropylene, phenoxy resins, styrene—butadiene copolymers, ethylene—ethyl acrylate copolymers, and low, and low density polypropylene are used in the compounded state polyesters, polyamides, and polyurethanes are used in the mosdy uncompounded state. 

Organic peroxides are used in the polymer industry as thermal sources of free radicals. They are used primarily to initiate the polymerisation and copolymerisation of vinyl and diene monomers, eg, ethylene, vinyl chloride, styrene, acryUc acid and esters, methacrylic acid and esters, vinyl acetate, acrylonitrile, and butadiene (see Initiators). They ate also used to cute or cross-link resins, eg, unsaturated polyester—styrene blends, thermoplastics such as polyethylene, elastomers such as ethylene—propylene copolymers and terpolymers and ethylene—vinyl acetate copolymer, and mbbets such as siUcone mbbet and styrene-butadiene mbbet. 

Pubhcations on curing polymers with TAIC include TEE—propylene copolymer (135), TEE—propylene—perfluoroaHyl ether (136), ethylene—chlorotrifluoroethylene copolymers (137), polyethylene (138), ethylene—vinyl acetate copolymers (139), polybutadienes (140), PVC (141), polyamide (142), polyester (143), poly(ethylene terephthalate) (144), sdoxane elastomers (145), maleimide polymers (146), and polyimide esters (147). 

Substituted amides (not of the alkanolamide variety) are sold to diverse low volume markets. They have some utility ki polymers such as polyethylene, ethylene-vinyl acetate copolymers, acryUc polymers, PVC, polyamides, and polyesters. They have been found effective as pharmaceutical processkig aids, defoamers (qv), antimicrobials, pesticides, kisect repellents, dispersion stabilizers, and corrosion inhibitors. 

Rosin, modified rosins, and derivatives are used in hot-melt adhesives. They are based primarily on ethylene—vinyl acetate copolymers. The rosin derivative is used in approximately a 1 1 1 concentration with the polymer and a wax. The resin provides specific adhesion to the substrates and reduces the viscosity at elevated temperatures, allowing the adhesive to be appHed as a molten material. 

Polymers ndResins. / fZ-Butyl peroxyneopentanoate and other peroxyesters of neopentanoic acid can be used as free-radical initiators for the polymeri2ation of vinyl chloride [75-01-4] (38) or of ethylene [74-85-1]. These peresters have also been used in the preparation of ethylene—vinyl acetate copolymers [24937-78-8] (39), modified polyester granules (40), graft polymers of arninoalkyl acrylates with vinyl chloride resins (41), and copolymers of A/-vinyl-pyrrohdinone [88-12-0] and vinyl acetate [108-05-4] (42). They can also be used as curing agents for unsaturated polyesters (43). 

Although current matrix diffusional systems are most suitable for small-molecule compounds, it has been demonstrated (84) that soHd hydrophobic polymers allow dispersed powdered macromolecules of nearly any size, for example, ethylene—vinyl acetate copolymers containing dispersed polypeptides, to be released for periods exceeding 100 days. 

Poly(ethylene-i (9-vinyl alcohol) is made by saponification of ethylene—vinyl acetate copolymers. The properties of these materials depend on the amount of vinyl alcohol present in the copolymer. High vinyl alcohol content results in more hydrophilic materials possessing higher densities, stiffness, and moduh. They are used commercially as barrier resins for packaging. Important producers include Du Pont and EVALCA (74) (see Barrier polymers). 

Among the different pressure sensitive adhesives, acrylates are unique because they are one of the few materials that can be synthesized to be inherently tacky. Indeed, polyvinylethers, some amorphous polyolefins, and some ethylene-vinyl acetate copolymers are the only other polymers that share this unique property. Because of the access to a wide range of commercial monomers, their relatively low cost, and their ease of polymerization, acrylates have become the dominant single component pressure sensitive adhesive materials used in the industry. Other PSAs, such as those based on natural rubber or synthetic block copolymers with rubbery midblock require compounding of the elastomer with low molecular weight additives such as tackifiers, oils, and/or plasticizers. The absence of these low molecular weight additives can have some desirable advantages, such as ... 

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... 

The molecules join together to form a long chain-like molecule which may contain many thousands of ethylene units. Such a molecule is referred to as a polymer, in this case polyethylene, whilst in this context ethylene is referred to as a monomer. Styrene, propylene, vinyl chloride, vinyl acetate and methyl methacrylate are other examples of monomers which can polymerise in this way. Sometimes two monomers may be reacted together so that residues of both are to be found in the same chain. Such materials are known as copolymers and are exemplified by ethylene-vinyl acetate copolymers and styrene-acrylonitrile copolymers. 

It has been found that, for a fixed mineral filler content, the viscosity of PMF-based composites increases when the coat is made of polyethylene [164, 209, 293], poly(vinyl chloride) [316] and polypropylene [326, 327], The picture was different, however, for composites based on the ethylene/vinyl acetate copolymer to which kaolin with grafted poly (vinyl acetate) was added [336]. Addition of PMF with a minimum quantity of grafted polymer results in a sharp drop of flowability (rise of viscosity), in comparison to addition of unmodified filler but with a further increase of the quantity of grafted polymer the flow gradually increases and, depending on the kaolin content and quantity of grafted polymer, may even become higher than in specimens with unmodified filler, for equal concentrations. 

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. 

Implants in the rabbit corneas exhibited no observable inflammatory characteristics over a period of 6 weeks. Compared to other previously tested polymers, the inertness of these polyanhydrides rivals that of the biocompatible poly(hydroxyethyl methacrylate) and ethylene-vinyl acetate copolymer. Histological examination of the removed corneas also revealed the absence of inflammatory cells (21)... 

H., High-temperature coupling of high-speed GPC with continued viscome-try. II. Ethylene-vinyl acetate copolymers, /. Appl. Polym. Sci., 29, 1569, 1984. 

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. 

How does the vinyl acetate content in ethylene vinyl acetate copolymer affect the properties of the polymer ... 

A product is only considered to be totally biodegradable if all its single components can be degraded naturally. Currently, pressure sensitive adhesives (PSA) are mostly based on non-biodegradable synthetic polymers such as polyacrylates, ethylene-vinyl acetate copolymers and styrene block copolymers [124]. Therefore there is a growing demand for the application of biodegradable PSAs on naturally degradable products like paper and cardboard. 

Nondegradable polymers are also useful as matrices for ocular implants. This application requires the polymer to be hydrophilic, to minimize local tissue irritation. Need for ocular implants stems from the challenges posed to conventional ocular medicines (i.e., eye drops) such as rapid dilution, tear washout, poor patient compliance, and limited bioavailability. Ocular implants from hydrophilic polymer matrices that provide localized sustained release may overcome the above limitations. The first polymeric sustained release product to reach the market was Ocusert , a pilocarpin sustained release ocular implant developed by Alza. Ocusert has the drug reservoir as a thin disc of pilocarpine-alginate complex sandwiched between two transparent discs of microporous membrane fabricated from ethylene-vinyl acetate copolymer. The microporous membranes permit the tear fluid to penetrate into the drug reservoir compartment to dissolve pilocarpine from the complex. Pilocarpine molecules are then released at a constant rate of 20 or 40 pg/hr for a four- to seven-day management of glaucoma. 

The most current method of nitroglycerin application is a transdermal device or skin patch. A cross section of such a patch is illustrated in Figure 6. The patch is actually a multi-layered polymer stack. The semipermeable membrane which comes in contact with the skin is usually composed of an ethylene-vinyl acetate copolymer or polypropylene. The reservoir contains the drug in a hydrogel or polymer matrix or solvent (the material must be chosen to insure uniform delivery). Examples of some solvents used include dimethyl sulfoxide (DMSO), sodium lauryl sulfate (SDS - a detergent) and propylene glycol/oleic acid. 

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. 

Some authors took advantage of the reactivity of polymers with ozone to recycle some peculiar plastic wastes coming from different origins. In this way, Fargere [155, 156] succeeded in degradation of cross-linked ethylene-vinyl acetate copolymers used in the production of sport shoes. This operation was achieved on grinded industrial wastes in suspension in CC14. In a second... 

At room temperature, PE is a semi-crystalline plastomer (a plastic which on stretching shows elongation like an elastomer), but on heating crystallites melt and the polymer passes through an elastomeric phase. Similarly, by hindering the crystallisation of PE (that is, by incorporating new chain elements), amorphous curable rubbery materials like ethylene propylene copolymer (EPM), ethylene propylene diene terpolymer (EPDM), ethylene-vinyl acetate copolymer (EVA), chlorinated polyethylene (CM), and chlorosulphonated polyethylene (CSM) can be prepared. 

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