HANWHA EVA 1529 (em inglês)

Within the ethylene-vinyl acetate copolymer portfolio offered by Hanwha Chemical Corporation, grade EVA 1529 is classified as a 15 wt% vinyl acetate resin with a nominal melt mass-flow rate of 2.9 g/10 min when determined at 190 °C under a 2.16 kg load in accordance with ASTM D1238-20 or ISO 1133-1:2022 Procedure A. The polymer is supplied as translucent pellets with a typical density of 0.938 g/cm³ measured by ASTM D1505-18. The 15 wt% vinyl acetate level positions EVA 1529 between lower-comonomer extrusion coating grades and higher-comonomer footwear or encapsulant resins; the acetate side groups reduce crystalline order relative to low-density polyethylene, lowering the melting peak while increasing flexibility and impact behaviour in moulded and foamed articles. The nominal melt endotherm by differential scanning calorimetry under ASTM D3418-21 is commonly reported at 86 °C, although the exact peak shifts with heating rate, annealing history, and lot-specific branching distribution. Because the melt index is relatively low, the resin retains melt strength during foaming and extrudate formation but generates higher head pressure than high-flow grades at equivalent screw speed.

Values in the preceding table are representative for ethylene-vinyl acetate copolymers with 15 wt% vinyl acetate, not an exact certificate of analysis for every production lot. Final part properties depend on processing history, additive package, and specimen preparation.

What Limits the Peroxide Cure Window When EVA 1529 Is Used in Crosslinked Foam?

In closed-mould ethylene-vinyl acetate foam production, EVA 1529 is typically compounded with dicumyl peroxide as crosslinking agent and azodicarbonamide as chemical blowing agent. The processing window is controlled by the competition between peroxide decomposition and gas evolution. On a 110 L intermeshing internal mixer used for masterbatch preparation, drop temperatures are maintained between 95 °C and 105 °C to avoid premature crosslinking while dispersing the peroxide and blowing agent. The discharged sheet is then calendered on a two-roll mill, transferred to a multi-platen press, and cured at 160–170 °C. A ±5 °C deviation in cure temperature can alter the relative decomposition kinetics of dicumyl peroxide and azodicarbonamide. If the melt crosslinks too quickly before gas evolution, expansion is restricted and foam density rises above target. If gas evolution occurs before sufficient gelation, cell walls rupture and the product exhibits open-cell collapse or internal blisters. Production observations from equivalent EVA foam lines indicate that press platen temperature non-uniformity greater than ±5 °C produces density gradients exceeding 0.02 g/cm³ across a 300 mm × 300 mm sheet. To control this, multi-zone oil-heated platens with PID temperature control are used, and thermocouple verification is performed before each shift. In injection-foam variants, a single-screw reciprocating screw with 24:1 L/D and a shut-off nozzle is used, with barrel temperatures set from 160 °C to 180 °C and injection speed profiled to prevent premature expansion inside the screw. The low melt index of EVA 1529 assists melt strength during blowing but increases shear heating; screw speeds above 80 min⁻¹ on a 40 mm screw can generate local melt temperatures exceeding 200 °C, at which acetic acid evolution may begin. Therefore, screw-speed limits and vented barrel zones are specified for production equipment when processing EVA 1529 in continuous foam extrusion.

Thermal analysis of EVA 1529 by differential scanning calorimetry reveals a broad melting endotherm consistent with random incorporation of 15 wt% vinyl acetate. The reduced crystallinity, commonly 15–20 % relative to low-density polyethylene by density or X-ray estimates, produces softness and low-temperature flexibility. Mechanical testing of compression-moulded plaques by ASTM D638-14 Type IV specimens yields representative tensile strength at break of 14–18 MPa and elongation at break of 750–850 %. Shore A hardness values are commonly reported at 89–92 by ASTM D2240-15e1. These properties support use in injection-moulded footwear shells, flexible gaskets, closure liners, and foamed midsole components. However, the hydrocarbon resistance of EVA 1529 is limited; the material swells in ketones, chlorinated solvents, and aromatic hydrocarbons, and continuous contact with mineral oil at elevated temperature is not recommended. Under sustained load, creep resistance is lower than semicrystalline polypropylene and some olefin block copolymers; therefore, structural or high-pressure sealing applications require additional design validation.

When Low-Temperature Flexibility Is Required, EVA 1828 Offers Increased Vinyl Acetate Content

When the application requires greater flexibility at −20 °C, the 15 wt% vinyl acetate content of EVA 1529 may be insufficient because low-temperature flexural modulus and impact strength improve as vinyl acetate content rises toward 18–28 wt%. In HANWHA EVA 1828, with a nominal 18 wt% vinyl acetate level and a melt index of 2.8 g/10 min, the additional comonomer further disrupts crystallinity and improves low-temperature flexibility and stress-crack resistance. Conversely, EVA 1529 retains higher thermal stability and greater stiffness than EVA 1828 because fewer acetate side groups are present. In extrusion coating and laminating where molten web stability is critical, EVA 1529 can be processed at lower melt temperatures than LDPE while maintaining adhesion to polar substrates such as aluminium foil and polyethylene terephthalate film. Corona-treated aluminium foil adhesion values for comparable EVA copolymers are typically 2–5 N/15 mm in peel testing, but specific adhesion depends on coating weight, back-pressure, substrate surface energy, and treatment level. When higher adhesion and hot-tack are required, HANWHA EVA 1828 may replace EVA 1529; when easier flow and shorter cycle times are dominant, a higher melt index grade such as EVA 1314 is typically selected.

On production-scale single-screw extruders, EVA 1529 is processed through a 24:1 to 28:1 L/D barrier screw with a compression ratio of 2.5:1 to 3.0:1. Barrel temperature profiles from the feed throat to the die are set between 150 °C and 180 °C, with the die held within 165–175 °C. Because the resin has a melt index of 2.9 g/10 min, head pressure rises more rapidly than with EVA 1314 at identical screw speeds; this pressure can be used for downstream filtration and static-mixing homogeneity. In blown film operations, die gaps of 0.8–1.2 mm and blow-up ratios of 2:1 to 3:1 are common for equivalent EVA resins, but published data for this specific configuration of EVA 1529 is limited. Excessive melt temperature above 220 °C should be avoided because thermal deacetylation may generate acetic acid, causing equipment corrosion and odour defects. Many downstream processors specify pre-drying at 60–70 °C for 2 h when sacks have been stored at relative humidity above 60 %, although the resin’s water absorption is relatively low. Regrind levels up to 20 wt% are tolerated in non-critical thick-section parts, but higher regrind fractions reduce impact strength and increase gel particles in film applications. Screw and barrel metallurgy should be nitride-treated or bimetallic when processing EVA 1529 with peroxide masterbatches, because residual peroxides can cause iron-catalysed degradation.

Injection Moulding Shrinkage and Clamp Force Behaviours in EVA 1529

Injection moulding of EVA 1529 is typically performed on hydromechanical or toggle clamp machines with clamp tonnage calculated from projected area and a cavity pressure of 30–50 MPa. The material’s low melt index requires a higher melt temperature and slower injection than polypropylene; typical barrel settings are 160–190 °C, mould temperature 20–40 °C, and injection speed 40–80 mm/s on a 40 mm screw. Mould shrinkage is anisotropic and depends on wall thickness; transverse shrinkage values of 1.2–2.0 % are observed in 2 mm plaques, while longitudinal shrinkage is 0.8–1.5 %. These ranges are derived from ASTM D955-21 measurements on equivalent EVA copolymers, and part-specific losses require gate location and packing studies. Because EVA 1529 remains flexible after solidification, ejector pin marks can be deeper than with rigid thermoplastics; draft angles of 1° to 2° are specified on ribs and sidewalls. The material is incompatible with polyoxymethylene during melt blending due to acid formation and phase separation, and direct feed of EVA 1529 into a barrel used for polyoxymethylene without purging can cause gas defects. On vertical-clamp injection machines used for overmoulding, the resin bonds adequately to polar substrates when surface temperatures exceed 60 °C, but adhesive promoters are required for non-polar polyolefin substrates. Published data for this specific configuration is limited.

Regulatory conformance of EVA 1529 is assessed against European Union REACH regulation (EC) No 1907/2006 for monomer and additive substances, and against the Restriction of Hazardous Substances Directive 2011/65/EU for lead, cadmium, mercury, hexavalent chromium, PBB, and PBDE when supplied for electrical and electronic equipment components. Ethylene-vinyl acetate copolymers may be evaluated for food contact under 21 CFR 177.1350 in the United States, but finished-article compliance depends on the additive package, layer structure, and migration testing under the intended conditions of use. Halogen-free formulation requests require confirmation that processing aids, slip agents, and colour masterbatches do not introduce fluorinated or brominated substances. When phthalate-free declarations are required for footwear or child-care articles, the supplier’s certificate of analysis should specify detection limits below 0.01 % by mass for each restricted phthalate. No animal-derived substances are intentionally used in the base polymer; however, downstream modification can alter this status. The base resin should not be incinerated at temperatures below 800 °C without adequate afterburner capacity because incomplete combustion of vinyl acetate copolymers can generate acetic acid and carbon monoxide. In blow-moulding and sheet extrusion operations using trim scrap, closed-loop regrind systems are acceptable if fines are removed by dedusting to prevent gel formation and surface defects. Lot-to-lot variation in melt index should be monitored by inline capillary rheometry or ASTM D1238-20 spot checks; a drift greater than ±0.3 g/10 min from the nominal 2.9 g/10 min can indicate formulation or polymerization excursion and should trigger purge and machine setting review.