Vinyl acetate in EVA

The use of photoacoustic FTIR spectroscopy in quantitative analysis of polymers was investigated with reference to determination of vinyl acetate in EVA, acrylonitrile in NBR, ethylene in EPDM, styrene in SBR and vinyl-butadiene in SBR. The results obtained indicated that, despite the theoretical complexities of photoacoustic FTIR spectroscopy, simple quantitative relationships could be found for many of these polymer analyses. 24 refs. 

Table I. Nominal and measured concentrations of vinyl acetate in EVA copolymers.

The polyethylene layer shows a series of fault lines that run perpendicular to the direction of applied stress. The fracture surface of the polyethylene is sharp and jagged, and shows no signs of elongation or ductility. Beneath the polyethylene layer "2" was a thin layer ("3") that was identified as ethylene/vinyl acetate copolymer (EVA). The EVA layer did show evidence of ductile failure in the SEM images. 

Ethylene-Vinyl Acetate Copolymer (EVA, EAM) Designation in ISO 1629 - EAM Repeat Unit... 

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]... 

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. 

In both Europe and the United States, aluminum trihydrate, or ATH [Al(OH)3)], has by far the largest share of the mineral flame-retardant market however, magnesium hydroxide presently has the highest growth rate. To date, most of the research using magnesium hydroxide has focused on thermoplastics, including ethylene-vinyl acetate copolymer (EVA), polypropylene, acrylonitrile-butadiene-styrene (ABS) copolymer, and modified polyphenylene oxide (Hornsby and Watson, 1986). 

In 1968 we reported on the effect of the monomer radical activities on the grafting of various vinyl monomers onto ethylene-vinyl acetate copolymers (EVA) (I). We found that the grafting activity of vinyl monomers corresponds to the monomer radical activity published by Mayo and Walling (2) and others (3, 4). This feature of vinyl monomers is depicted in Figure 1. 

In more polar substances such as ethylene-vinyl acetate copolymers (EVA), the low molecular weight HALS-I can be used. However, in this substrate too, the polymeric HALS-II and HALS-III are... 

Ocusert provides uniform controlled release (20 or 40 pg/h for 7 days) of pilocarpine as an ocular hypotensive drug and has been commercialized in 1974. Ocusert consists of two outer layers of ethylene-vinyl acetate copolymer (EVA) and an inner layer of pilocarpine in alginate gel within di-(ethylhexyl) phthalate for a release enhancer, sandwiched between EVA layers. ... 

Acrylonitrile-butadiene rubber, NBR, styrene-aciylonitrile rubber, SAN, ethylene-vinyl acetate copolymer, EVA, and acrylic copolymers are helpful modifications of polyvinylchloride that change its processing characteristics and elastomeric properties. Blending with these copolymers helps to reduce the requirement for low molecular weight plasticizers. Ethylene-vinyl acetate copolymer plays a role of high molecular weight plasticizer in production of vinyl hose. This reduces the amount of DOP used in flexible hose applications. Ethylene copolymer is used plasticize PVC that reduces gel. "" Phthalate plasticizers can be eliminated from water based adhesives because of utilization of vinyl acetate ethylene copolymer as a high molecular plasticizer/modifier. " ... 

Continuous stirred-tank reactors (CSTRs) are used for large productions of a reduced number of polymer grades. Coordination catalysts are used in the production of LLDPE by solution polymerization (Dowlex, DSM Compact process [29]), of HDPE in slurry (Mitsui CX-process [30]) and of polypropylene in stirred bed gas phase reactors (BP process [22], Novolen process [31]). LDPE and ethylene-vinyl acetate copolymers (EVA) are produced by free-radical polymerization in bulk in a continuous autoclave reactor [30]. A substantial fraction of the SBR used for tires is produced by coagulating the SBR latex produced by emulsion polymerization in a battery of about 10 CSTRs in series [32]. The CSTRs are characterized by a broad residence time distribution, which affects to product properties. For example, latexes with narrow particle size distribution cannot be produced in CSTRs. 

Most hot-melts are based on polyolefins. The best known hot-melt is ethylene-vinyl acetate copolymer (EVA), e.g., duPont Elvax. In 1983, duPont added a new line of resins... 

Ethylene-vinyl acetate copolymers EVA with 27-29% of VAc were fractionated by fractional precipitation. Viscosity data and SEC data for these fractions in tHF at 20°C were obtained. The Mark-Houwink constants were calculated using eqn (5.24) [21] ... 

Ethylene is copolymerized with many nonolefinic monomers, particularly acrylic acid variants and vinyl acetate, with EVA polymers being the most commercially significant. All of the copolymers discussed in this section necessarily involve disruption of the regular, crystallizable PE homopolymer and as such feature reduced yield stresses and moduli, with improved low-temperature flexibihty. 

Melt adhesives are based on thermoplastics but usually contain a number of other components. The most commonly used melt adhesives are based on Ethylene-vinyl acetate copolymers (EVA copolymers), but polyethylene, polyesters, polyamides and thermoplastic rubbers, for example, styrene-butadiene block copolymers, are also used. Depending upon the properties required, the vinyl acetate content in the EVA copolymer may... 

Ethylene-vinyl acetate copolymers (EVA) have been successfully used for this approach with the particle size of the dispersed phase ranging from about 0.5 to 5.0 p.m. To be effective as tougheners, the surface of the particle generally needs either to react with or to adhere well to the matrix electron microscopy has confirmed the latter case to be true in the case of EVA copolymers. 

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