Greenflex MP 34 BCA EVA Copolymer Resin,Atribuído Bio-Circular,Grado de Alta Fluididade

Greenflex MP 34 BCA EVA Copolymer Resin, Bio-Circular Attributed, High Fluidity Grade, is an ethylene-vinyl acetate copolymer in which the polymer backbone is a statistical copolymer of ethylene and vinyl acetate. The numerical designation 34 identifies the nominal vinyl acetate content of 34 wt%; the BCA suffix indicates bio-circular attributed feedstock accounting rather than a physically segregated renewable monomer stream. The material is supplied in pellet form for extrusion, compounding, hot-melt adhesive, and injection-moulding operations where high melt fluidity and polar comonomer functionality are required. Incoming quality control should verify the lot-specific values for melt mass-flow rate, vinyl acetate content, density, and ash content against the supplier certificate of analysis because bio-circular attributed lots are drop-in equivalents to their fossil counterparts but remain subject to normal lot-to-lot rheological variation.

The grade is positioned against low-VA EVA film grades by its lower crystallinity and higher surface polarity. The high vinyl acetate content reduces the crystalline ethylene sequence length, producing a broad melting endotherm rather than a sharp melting point. Differential scanning calorimetry according to ISO 11357-3 typically shows a melt endotherm in the region of 45–75 °C for similar high-VA copolymers, but the exact values are grade-specific and should be taken from the technical datasheet. Density measured by ISO 1183-1 generally falls in the 0.950–0.970 g/cm³ class envelope. These values are not a product guarantee; they define the class of 34 wt% VA high-fluidity EVA resins.

Table 1 summarizes the properties that are typically controlled on a certificate of analysis for this grade class and the governing test standards. The range entries are class-typical values for high-VA EVA resins and do not replace supplier datasheet values or lot-specific CoA data.

What Distinguishes the MP 34 BCA from Conventional EVA Copolymer Resins?

The difference is primarily compositional, not chain-architectural. A 34 wt% vinyl acetate level places the resin in the high-VA EVA class, which exhibits significantly reduced polyethylene crystallinity relative to 9–18 wt% VA grades. The consequence is a lower flexural modulus, greater elongation, lower hardness, and stronger adhesion to polar substrates such as polyvinyl chloride, polyurethane, aluminium, and glass after melt coating. In contrast, low-VA EVA grades retain more polyethylene-like stiffness and barrier character but have poorer low-temperature flexibility and less surface tack. The MP 34 BCA polar acetate groups also improve compatibility with rosin ester and hydrocarbon tackifiers in adhesive systems, although compatibility limits with wholly aliphatic waxes must be established by cloud-point titration or hot-stage microscopy.

Relative to metallocene polyolefin plastomers of similar hardness, the EVA grade has a stronger hydrogen-bond-accepting character due to the acetate carbonyl, higher surface energy, and a more pronounced tendency to evolve acetic acid under prolonged high-temperature processing. The processing window is therefore narrower above 190 °C. Compared with ethylene-butyl acrylate copolymers, EVA generally shows greater polarity and lower thermal stability, but the MP 34 BCA high-fluidity designation allows processing on smaller extruders and low-pressure moulding machines.

Rheological Specification Limits and Thermal Stability Envelope

The melt mass-flow rate is controlled according to ISO 1133-1:2022 at 190 °C under 2.16 kg. The product is classified as a high-fluidity grade, meaning that it is intended for applications requiring short cycle times, low injection pressure, or efficient wet-out in hot-melt mixing. The exact grade-specific value must be read from the CoA; an incoming inspection programme should use an internal acceptance band defined by the converter’s tolerance for viscosity variation because melt flow variability in this fluidity range can shift adhesive viscosity and masterbatch letdown ratios.

Thermal stability is the critical boundary. EVA resins containing 34 wt% vinyl acetate undergo deacetylation at elevated temperatures, liberating acetic acid. The reaction is temperature-dependent and autocatalytic: once acetic acid is released, it promotes further degradation. Therefore, melt temperatures should not exceed 190 °C for continuous operation; excursions above 200 °C should be limited to short purges. Equipment surfaces in contact with the melt should be chrome-plated or manufactured from nitrided steel because traces of acetic acid corrode carbon steel over prolonged campaigns. Twin-screw extruder barrels with a length/diameter ratio of 24:1 to 40:1 should be vented to remove volatiles; vacuum venting at -0.04 to -0.06 MPa gauge is typical in compounding lines.

Moisture uptake is not the primary drying driver for EVA, but surface condensation can create steam splay and increase hydrolytic degradation during processing. If pellets have been stored below their dew point or in humid ambient conditions, pre-drying is required. A dehumidified-air dryer set to 50–60 °C for 4–6 h with a dew point below -20 °C is commonly used. Drying above 70 °C should be avoided because pellet blocking and antioxidant migration can occur. Blends containing hygroscopic fillers or masterbatches may require separate drying before extrusion.

When Hot-Melt Adhesive Compounding Requires Sustained Viscosity Control

In hot-melt adhesive production, the EVA resin functions as the polymeric backbone that provides cohesion, tensile strength, and substrate wetting. It is typically compounded with tackifier resins, waxes, and stabilizers in jacketed sigma-blade kneaders, planetary mixers, or continuous twin-screw extruders. Processing temperatures are maintained between 160 °C and 175 °C to balance low mix viscosity against thermal degradation. Viscosity stability should be monitored over the expected production hold time. ASTM D4499-07, Standard Test Method for Heat Stability of Hot-Melt Adhesives, is a recognized method for comparing viscosity drift under controlled temperature.

A starting-formulation envelope for EVA hot-melt pressure-sensitive and packaging adhesives is 25–40 wt% EVA, 30–50 wt% tackifier, 20–35 wt% wax, and 0.5–1.5 wt% antioxidant. The high vinyl acetate content of MP 34 BCA increases compatibility with polar tackifiers such as rosin esters. High fluidity reduces the time required to reach homogeneous clarity in batch mixers, but high shear should not be used to compensate for insufficient tackifier softening.

Adhesive formulators should not interpret the high fluidity as a license to lower mixing temperatures below the tackifier softening point. Incomplete dispersion of high-softening-point rosin esters results in phase-separated adhesive films with reduced peel adhesion and brittle failure at low temperature. A short pre-blend of EVA and tackifier at 150–160 °C before wax addition improves clarity and prevents localised thermal gradients. The mixer should be blanketed with nitrogen if the hold time exceeds 6 h; otherwise surface skinning and colour development occur.

Using the Grade as a Polymer Modifier in Impact-Toughened Formulations

The resin can be melt-compounded with polyethylene, polypropylene, or post-industrial reclaim to reduce stiffness and improve stress-cracking resistance. The optimum addition level is normally in the 10–25 wt% range, but the exact loading depends on the base resin melt index, the target flexural modulus, and the final part geometry. Twin-screw compounding with dispersive mixing elements is preferred because simple pellet blending followed by direct injection moulding often gives gross phase separation. When evaluated by ISO 527-2, the resulting blends typically show a reduction in tensile stress at yield and an increase in elongation at break relative to unmodified polyethylene. The magnitude of the change is formulation-specific; published data for this specific bio-circular attributed grade in all polyolefin matrices is limited.

In polypropylene, EVA is generally immiscible and should not be used as an impact modifier unless combined with a compatibilizer or an elastomeric olefin copolymer. The vinyl acetate groups do not provide sufficient interfacial adhesion to isotactic polypropylene; the dispersed domains remain large and can reduce weld-line strength. In polyethylene-rich matrices, the olefinic segment of EVA is more compatible, and the high melt fluidity of MP 34 BCA assists in distributing the modifier at lower specific energy input.

For Injection Moulding, Fluidity Must Be Balanced Against Acetic Acid Generation

Injection moulding of high-VA EVA is typically confined to footwear components, soft-touch overmouldings, and flexible technical items. The high melt fluidity enables filling of thin sections at barrel temperatures of 140–180 °C, but the thermal degradation boundary of vinyl acetate polymer does not permit the high-temperature processing common to rigid polyolefins. Screw recovery speed should be set to avoid excessive shear heating; the melt temperature should be measured with an immersion pyrometer from a purged shot and kept below 185 °C. The use of a general-purpose check ring is acceptable for unfilled material, but reverse-taper nozzles are preferred to prevent drooling at low melt viscosity.

For regulatory documentation, the resin is subject to the requirements of Regulation (EC) No 1907/2006 (REACH). Compliance with RoHS Directive 2011/65/EU Annex II restrictions on lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE should be confirmed through supplier documentation. For food-contact articles in the European Union, the finished article must comply with Regulation (EU) No 10/2011 on plastic materials and articles intended to come into contact with food, including overall migration limits. In the United States, EVA copolymers may be evaluated under 21 CFR 177.1350, but final article compliance remains the converter's responsibility.

Table 2 lists compliance documentation that should be present on the supplier certificate or sustainability declaration.

Bio-circular attribution under ISCC PLUS is an accounting mechanism that assigns renewable or circular feedstock credits to specific production volumes. The polymer is not necessarily physically different from its fossil-based analogue; the BCA suffix certifies that the feedstock balance has been verified by a third party. Biogenic carbon content may be reported as a percentage of total carbon using ASTM D6866-21 Method B or ISO 16620-2:2019. The actual biogenic carbon percentage is lot-specific and should be requested on the sustainability certificate, not read from a generic brochure. Users should maintain mass-balance documentation for the entire supply chain because a break in chain-of-custody invalidates the sustainability claim.

Storage is recommended in unopened original packaging at temperatures below 40 °C and away from direct sunlight. Under such conditions, EVA resins typically retain processability for at least 24 months from the production date, but material that has been exposed to elevated ambient temperatures should be inspected for pellet agglomeration. Agglomerated pellets must not be force-fed into a granulator or extruder without sieving because compacted material can cause feed bridging and tooth damage.