Ethylene-vinyl acetate copolymers extrusion

Figure 27 Low density polyethylene and ethylene-vinyl acetate copolymer extrusion products.

ISO 4613-1 1993 Plastics - Ethylene/vinyl acetate (E/VAC) moulding and extrusion materials - Part 1 Designation and specification ISO 4613-2 1995 Plastics - Ethylene/vinyl acetate (E/VAC) moulding and extrusion materials - Part 2 Preparation of test specimens and determination of properties ISO 8985 1998 Plastics - Ethylene/vinyl acetate copolymer (EVAC) thermoplastics -Determination of vinyl acetate content... 

S.E. Barnes, E.C. Brown, M.G. Sibley, H.G.M. Edwards and P.D. Coates, Vibrational spectroscopic and ultrasound analysis for the in-process monitoring of poly(ethylene vinyl acetate) copolymer composition during melt extrusion, Analyst, 130, 286-292 (2005). 

R. Reed, Moldable Ethylene/Vinyl Acetate Copolymer , USP 4090894 (1978) CA 39, 148908 (1978) [Vinyl acetate copolymerized with ethylene is used as a desensitizer and binder for moldable expl compns of cyclic nitramines such as RDX. From 82 to 98 wt % of binder is used, and various ratios of ethylene to vinyl acetate moieties in the resin are utilized to modify molding and extrusion properties. Prepn of typical compns consists of dissolving the copolymer in benz and addition with stirring to an RDX/w slurry, which is stirred until mixt is complete, followed by filtration and drying. Table 1 presents properties of sample compns with and without the ethylene/vinyl acetate copolymer (EVA). The inventor also states that the EVA, unlike other polymeric binders, endothermically breaks down at high temps and acts as a heat sink for the expl content]... 

Hydrolyzed ethylene—vinyl acetate copolymers [24937-78-8]> commonly known as ethylene—vinyl alcohol (EVOH) copolymers [25067-34-9], are usually used as extrusion resins, although some may be used in solvent-coating applications. As the ethylene fraction of these semicrystalline copolymers increases, the melting temperature decreases, the permeabilities increase, and the sensitivity to humidity decreases. The permeabilities as a function of polymer composition and humidity are shown in Figure 2. Vinyl alcohol homopolymer [9002-89-5] has a very low oxygen permeability in dry conditions however, the polymer is water-soluble. Trade names for these barrier polymers include Eval, Soamol, Selar OH, and Qarene. Table 6 lists the compositions... 

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. 

Trunec has described the thermoplastic extrusion of thin-wall tubes made of yttria-stabilized zirconia and gadolinia-doped ceria [Tru 04], These ceramics are used for solid oxide electrolyte applications, e.g. solid oxide fuel cells. The thermoplastic binder system used consists of ethylene-vinyl acetate copolymer, parafHn wax and stearic acid. With this system tubes with an outer diameter of 10.5 mm and wall thicknesses of 290 and 280 pm could be fabricated. 

Polypropylene, 35 wt% PP, was blended with polyisobutylene, 50 wt% PIB, and ethylene-vinyl acetate copolymer, 15 wt% EVAc, to give alloys useful for films, moldings, and extrusions C. B. Shulman, Emopean Patent Appl., 116,783, 29 Aug 1984, Appl. 27 Dec 1982, to Exxon Research and Eng. Co. 

U. Sundararaj and F. Zhang, Nanocomposites of ethylene-vinyl acetate copolymer (EVA) and organoclay prepared by twin-screw melt extrusion. Polymer Composites, 25 (2004), 535 2. 

In the examination of potential applications for these unique materials that possess a wide variety of properties depending on copolymer composition, the Dow group examined finished articles formed by injection and blow molding, blown and cast film and melt extrusion. Potential applications for these new materials would be as substitute materials for flexible PVC, styrenic block copolymers, ethylene/vinyl acetate copolymers and ethylene/propylene-based elastomers. These new ethylene/styrene copolymers once again demonstrate that new catalyst technology creates new markets and applications for the polyethylene industry by competing with materials outside of the polyethylene product mix. 

Extrusions and moldings Ethylene-vinyl acetate copolymer United States 4,157,362 1979 Toyo Soda... 

The vast majority of low density polyethylene and ethylene-vinyl acetate copolymer is converted into end products by extrusion, as shown in Figure 26. Other conversion processes account for less than 5% each. 

Ethylene]vinyl acetate. Symbolized as E/VAC according to ISO 1043 but the abbreviation of EVA is extensively used in the literature. Copolymer of ethylene and vinyl acetate. Its flexibility is similar to that of the plasticized PVC but in this case it is an inherent property due to the chemical structure without any incorporation of a plasticizer. As a thermoplastic, it is processed by extrusion or injection moulding. Strainability of E/VAC films is higher than that of LDPE. Applications injection moulded shoe soles, bathing sandals, and other consumer goods impact modifier for rigid PVC. Trade names Levapren (FRG), Ultrathene (USA). 

PP has been blended with polyvinylchloride (PVC) for extrusion of pipes or electrical insulation [4]. The blends are compatibilized by addition of either methylmethacrylate-butadiene-st)TCne copolymer (MBS), a graft copolymer of acrylonitrile-butadiene-styrene-methylmethacrylate (ABSM), ethylene-vinylchloride copolymer (VCE), ethylene-vinyl-acetate-vinylchloride copol5oner (EVAc-VC), EVAc, etc. The blends also comprised other resin, viz. PE, PS or SBR, PMMA or PC, etc. 

Ethylene-vinyl acetates (EVA) copolymers are in the polyolefin family of thermoplastics. They are used in all processes, particularly for extrusion, injection molding, and blow molding. They are used either alone or are coextruded or coinjected and used in compounds to provide unique properties. They approach elastomeric materials in their softness and flexibility. 

VAE, a copolymer of vinyl acetate with minor amounts of ethylene is used as an adhesive for paper, plastics and leather and as a binder for different paints. Shoes, tubes, toys and other articles of daily use also contain VAE polymers. The hydrolysis product of VAE polymers, EVOH, is a thermoplast and can therefore be processed by extrusion and injection moulding and is used as barrier polymer for O2 and CO2 (e.g. in packaging applications). 

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