Ethylene vinyl acetate polyethylene copolymer

Materials. Polyethylene (PE) Low density polyethylene (PE) and ethylene-vinyl acetate (EVA) copolymers with vinyl acetate (VA) contents of 9, 18, 25, 28, 33, and 40% were obtained from Scientific Polymer Products, Inc. 

Silicone mbber, especially poly dimethyl siloxane (Silastic) Silicone-carbonate copolymers, Surface-treated silicone mbbers Poly (ethylene-vinyl acetate), Polyethylene, Polyurethane (Walopur)... 

Films made with barrier polymers, e.g., polyamide (PA)/polyethylene (PE) laminates, ethylene vinyl acetate (EVA) copolymer/polyvinyl chloride (PVC)-polyvinylidene chloride (PVDC) copolymer laminates, and ionomer/ PA/EVA laminate films are used for vacuum packaging, particularly products like red meat. 

Application To produce low-density polyethylene (LDPE) homopolymers and ethylene vinyl acetate (EVA) copolymers using the high-pressure free radical process. Large-scale tubular reactors with a capacity in the range of 130,000 tpy-425,000 tpy, as well as stirred autoclave reactors with capacity around 125,000 tpy can be used. 

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 (EVA) copolymers, but polyethylene, polyesters, polyamides, and thermoplastic rubbers (e.g., styrene-butadiene block copolymers) are also used (see Adhesive Bonding of Plastics in Chapter 2). 

Ethylene-vinyl acetate (EVA) copolymers are used in HMAs. The EVA acts as the binder, contributing cohesive strength to the adhesive formulation. Typically, an EVA used in a ElMA is approximately 18-28 mol% vinyl acetate (VA). In an EVA copolymer, the crystalline polyethylene (PE) region provides strength, compatibility with the wax, and the desired high-temperature properties. The amorphous region containing both VA and PE provides compatibility with the tackifier. 

General Description Ethylene Vinyl Acetate (EVA) Copolymer is a copolymer resin ranging in vinyl acetate content from 7.5 wt% to 33 wt%. DuPont Elvax and Equistar Ultrathene grades vary by vinyl acetate content. Some grades are available with antiblock and slip additives. The vinyl acetate units in the copolymer modify the basic polyethylene structure and its properties. The addition of vinyl acetate to polyethylene provides lower sealing temperature, increased flexibility, improved optical properties, greater adhesion, increased impact, and puncture resistance. 

It is necessary to be able to identify and quantify the additives in polymers and vibrational spectroscopy is a particularly useful approach to this problem. Compared with traditional chemical analyses, vibrational methods are nondestructive and are time-and cost-effective as well as more precise. A large number of examples exist in the literature. For example, antistatic agents (polyethylene glycol (PEG) in polyethylene (PE)) can be detected directly using FTIR sampling (367). An IR spectroscopic technique for the analysis of stabilisers (2, 6-di-tert-butyM-methylphenol) in PE and ethylene-vinyl acetate (EVA) copolymer has been described (368). It is possible to quantify the amount of external and internal lubricants (stearic acid in polystyrene (PS)) (371). Fillers in polymers can also be analysed (white rice husk ash (predominantly silica in polypropylene (PP)) (268). Raman spectroscopy has been used to detect residual monomer in solid polymethyl methacrylate (PMMA) samples (326). 

Polyethylene, PE polypropylene, PP and their h(unologues were blended with ethylene—vinyl acetate, EVAc, copolymer and cured with Iree radicals into products showing desired impact strength and modulus. The blends were used for manufacturing of fibers, films, or moldings ... 

Ethylene-vinyl acetate (EVA) copolymers. EVA copolymers are given by the structure shown in Fig. 1.27 and find commercial importance in the coating, laminating, and film industries. EVA copolymers typically contain between 10 and 15 mol % vinyl acetate, which provides a bulky, polar pendant group to the ethylene and provides an opportunity to tailor the end properties by optimizing the vinyl acetate content. Very low vinyl-acetate content (approximately 3 mol %) results in a copolymer which is essentially a modified low-density polyethylene, " with an even further reduced regular structure. The resultant copolymer is used as a film due to its flexibility and surface gloss. Vinyl acetate is a... 

Thermoplastics used to blend with NR include PS, " polyamide 6, ethylene-vinyl acetate (EVA) copolymer, poly(methyl methacrylate) (PMMA), polypropylene (PP), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) " and high-density polyethylene (HDPE). To improve the properties of TPNR, modified NR is also used. ENR is the most frequently used modified NR. TPNR blends are prepared by blending NR and thermoplastics in various proportions. The role of rubber is to improve the impact strength and ductility of the plastic. Depending on the ratio, materials with a wide range of properties are obtained. The stiffness of the rubber is increased with the incorporation of plastic into the rubber matrix. The mechanical properties of TPNR again depend on the proportions of the rubber and thermoplastic components. The elastic properties of TPNR are considerably... 

Flgme 2. (a) Crystallization curves of high-density polyethylene and ethylene-vinyl acetate random copolymers with various vinyl acetate content, cooling rate = 10 °C/ min The vinyl acetate content is indicated at each curve. Exotherm is up. (b) melting curves of the same samples recorded at 10°C/min heating rates. Endotherm is down. Samples from Scientific Polymer Products, Inc. (Menczel, unpublished results.)... 

Blends of PE with PVC have been compatibilized using graft copolymers of ethylene and vinyl chloride, chlorinated polyethylenes (CPE) and ethylene-vinyl acetate (EVA) copolymers. Compatibilized... 

Polyethylene has limited adhesion to paints and inks. This is because it is a non-polar hydrocarbon incapable of forming hydrogen bonds. Adhesion can be improved by copolymerizing ethylene with polar monomers such as ethyl acrylate or vinyl acetate to give ethylene ethyl acrylate (EEA) copolymers or ethylene vinyl acetate (EVA) copolymers. EVA is often used for shoe soles. 

Figure 4.10 FTIR absorbance spectra recorded at room temperature of an ethylene-vinyl acetate (EVA) copolymer blended with chlorinated polyethylene (CPE) and poly(vinyl chloride) (PVC). A, pure EVA B, 40 60 and C, 80 20 wt% CPE-EVA, respectively D, pure EVA E, 40 60 and F, 80 20 wt% PVC-EVA, respectively. Reproduced from ref. 197, by permission of the publishers Butterworth Heinemann Ltd .

The early hot melt adhesives were not strictly definable as rubber-based adhesives. Most rubber polymers such as natural rubber and random SBR are of such molecular weight and structure that they do not melt readily to a workable coating consistency at a temperature below which thermal degradation and decomposition take place. Certain synthetic polymers, however, lend themselves to the formulation of a wide range of hot melt adhesive compositions. Polyamide and polyester resins, ethylene-vinyl acetate (EVA) copolymers, ethylene-ethyl acrylate (EEA) copolymers, low molecular weight polyethylene and amorphous polypropylene, and certain vinyl ethers have found application in hot melt adhesives. These adhesives have found wide use in packaging, industrial, and construction applications. 

Depending on fashion, each year different materials have been and are currently used in the manufacturing of shoes, ranging from rubber soles (vulcanized styrene-butadiene rubber (SBR), thermoplastic rubber, EPDM) to different polymers (leather, polyurethanes, ethylene-vinyl acetate (EVA) copolymers, polyvinyl chloride (PVC), polyethylene, Phylon). To produce adequate adhesive joints, surface preparation of those materials is required (see part B Surface treatments). Surface preparation procedures for these materials must be quickly developed and the validity of these treatments is generally too short. Several procedures have been established to optimize the upper to sole bonding, most of them are based in the use of organic solvents. Due to environmental and health issues, solvents should be removed from the surface preparation procedure and several environmental friendly procedures for the surface preparation of several materials have been proposed. 

Figure 20 Melting temperature of rapidly crystallized fractions of polyethylene-based copolymers as determined by differential scanning calorimetry hydrogenated polybutadiene with ethyl groups A copoly(ethylene vinyl acetate) diazoalkane copolymer with propyl side groups A copoly(ethylene/l-butene) copoly(ethylene/l-octene)...

Blends can be formed with copolymers. Addition of EVA (ethylene vinyl acetate), a copolymer of vinyl acetate (VA) and ethylene, improves some of the properties of polyethylene. The concentration of VA in the final blend controls the crystallinity of PE an increase in VA concentration decreases the crystallinity of PE, providing a larger flexibility and transparency. In the same way, due to the polarity of the acetoxo side chains, an increase in VA concentration... 

Applications of the technique have been discussed in various fields. Willis and Wheeler demonstrated the determination of the vinyl acetate (VA) distribution in ethylene-vinyl acetate (EVA) copolymers, the analysis of branching in high-density polyethylene (PE), and the analysis of the chemical composition of a jet oil lubricant. Provder et showed that in powder coatings all additives were positively identified by SEC-FTIR through comparison of the known spectra. Even biocides could be analyzed in commercial house paints. The comparison of a PS-PMMA blend with a corresponding copolymer gave information on the chemical drift. The analysis of a competitive modified vinyl polymer sample by SEC-FTIR showed that some of the components of the binder could be identified readily as vinyl chloride, ethyl methacrylate, and acrylonitrile, and an epoxidized drying oil additive was detected. 

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. 

Fig. 10. Preparation and morphology of toughened PVC (a) secondary PVC grain (50—250 flm) (b) modified PVC with coherent primary grain (ca 1 -lm) (220). CPE = chlorinated polyethylene EVA = ethylene—vinyl acetate copolymers ABS = acrylonitrile—butadiene—styrene MBS = methyl...

The use of TAG as a curing agent continues to grow for polyolefins and olefin copolymer plastics and mbbers. Examples include polyethylene (109), chlorosulfonated polyethylene (110), polypropylene (111), ethylene—vinyl acetate (112), ethylene—propylene copolymer (113), acrylonitrile copolymers (114), and methylstyrene polymers (115). In ethylene—propylene copolymer mbber compositions. TAG has been used for injection molding of fenders (116). Unsaturated elastomers, such as EPDM, cross link with TAG by hydrogen abstraction and addition to double bonds in the presence of peroxyketal catalysts (117) (see Elastol rs, synthetic). 

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. 

The low vinyl acetate ethylene—vinyl acetate copolymers, ie, those containing 10—40 wt % vinyl acetate, are made by processes similar to those used to make low density polyethylene for which pressures are usually > 103 MPa (15,000 psi). A medium, ie, 45 wt % vinyl acetate copolymer with mbber-like properties is made by solution polymerisation in /-butyl alcohol at 34.5 MPa (5000 psi). The 70—95 wt % vinyl acetate emulsion copolymers are made in emulsion processes under ethylene pressures of 2.07—10.4 MPa (300—1500 psi). 

---