WENEW Braskem America DVR 001A EVA Copolymer,60% Recycled Content,Foam & Footwear Grade

Compression-moulded EVA midsoles produced with DVR 001A require a narrower processing window than virgin EVA because the recycled fraction introduces crosslinked gel domains, variable melt extensibility, and a slightly acidic residue profile. In a two-roll mill line, the compound is fluxed at 95–105 °C for 8–12 min before sheet-off, and dicumyl peroxide is added after the batch temperature drops below 90 °C to prevent premature decomposition. The peroxide level is set between 0.5 phr and 0.8 phr of 40 % active dicumyl peroxide; below 0.4 phr, compression set after 50 % deflection for 6 h at 50 °C per ISO 1856:2022 typically exceeds 30 %, and above 0.9 phr the crosslink density embrittles thin sidewall sections. Azodicarbonamide is maintained at 2.0–3.2 phr; above 3.5 phr, internal gas pressure during press cure generates split-level voids at the midsole centre. Zinc oxide at 0.8–1.2 phr and stearic acid at 0.3–0.5 phr are used to control blowing agent decomposition and release behaviour. Calcium carbonate at 5–15 phr functions as a nucleating agent and shrink compensator, but loadings above 20 phr raise foam density beyond the target range for athletic midsoles. Amine-based antistatic additives should be excluded from peroxide-cured DVR 001A formulations because they scavenge free radicals and suppress crosslink density.

Preform loading is set at 70–80 % of cavity volume to produce free expansion without excessive flash. Press cure is conducted at 160–165 °C under hydraulic pressure of 150 kg/cm²; moulding time is 8–10 min per 10 mm of unbounded thickness. After demoulding, the foam is stabilised at 60 °C for 24 h to release residual gases and allow dimensional relaxation. Final density is targeted at 0.18–0.25 g/cm³ per ASTM D792-20, Shore C hardness at 55–65 per ASTM D2240-15(2021), and rebound resilience at 40–50 % per DIN 53512. The recycled fraction in DVR 001A can contain crosslinked EVA chips from post-industrial footwear skiving and die-cut waste; these particles remain discrete in the melt phase and form visible pinholes in midsoles below 4 mm wall thickness. If incoming regrind is not sieved below 300 µm, surface pitting and reduced tear strength increase in production-scale runs. On continuous foamed sheet lines, a screen pack of 60/100/60 mesh is used, with pressure alarms set to trigger at a differential above 80 bar.

Can DVR 001A Be Directly Injection Moulded Into Single-Piece Sandal Outsoles Without Losing Surface Finish?

Direct injection moulding of DVR 001A into single-piece sandal outsoles is possible only when melt-viscosity variation is managed lot by lot. The grade is processed in a reciprocating-screw machine with L/D ratio 20:1–24:1 and compression ratio 2.0:1–2.5:1; the screw should have a lightly nitrided surface because the recycled fraction may carry mildly acidic residues. Nozzle melt temperature is held at 175–195 °C, with the front zone 5–10 °C lower than the nozzle to limit premature blowing agent decomposition. Mould water temperature is set between 25 °C and 45 °C. Pre-drying in a desiccant dryer at 80 °C for 4 h is required when ambient relative humidity exceeds 60 %; target moisture content is below 0.05 %. A vented barrel with vacuum at −0.08 MPa reduces splay caused by volatile residues from the recycled feedstock. Lot-to-lot melt mass-flow rate is measured per ASTM D1238-20 at 190 °C/2.16 kg; if the value shifts more than 15 % from the running virgin EVA reference, short shots or flash imbalance appear in multi-cavity tools.

Fan gates of 1.5–2.0 mm depth with land length 3–5 mm are used for sole thickness of 4–6 mm. Injection speed is kept low to moderate to avoid shear heating that activates residual blowing agent prematurely at the gate. Hot runner needles with orifice below 0.5 mm are avoided because gel particles can block the valve. Mould shrinkage after 24 h is 1.2–1.8 %, and anisotropy increases when the post-industrial fraction exceeds 60 %; moving-core or dual-ejector set-ups compensate for this directional variation. Finished single-piece sandals, flip-flop soles, and clog shells are tested for Shore A hardness 55–75 per ASTM D2240-15(2021), tensile strength minimum 3.5 MPa per ISO 1798:2008, and elongation at break minimum 200 %. For children’s sandals sold in the U.S., CPSIA Section 108 limits DEHP, DBP, and BBP to 0.1 % each in accessible plastic components; converters should request phthalate-specific documentation from Braskem America for DVR 001A lots used in this segment.

Calendered EVA foam sheet is produced by mixing DVR 001A in an internal mixer at 110–120 °C, then discharging the batch to a two-roll mill fitted with chilled rolls at 80–90 °C to sheet off at 2.0–3.5 mm thickness before the blowing agent is fully activated. The sheet is then passed through a continuous hot-air oven or press lamination line at 180–200 °C to trigger azodicarbonamide decomposition; the foam expands to 0.12–0.20 g/cm³ and is calibrated in a three-roll stack at 0.5–0.8 MPa nip pressure. Because the recycled fraction contains low levels of ester-based monomers and oxidised particles, calendering release is improved with 0.3–0.5 phr stearic acid and a chilled release roll, but excessive stearic acid above 0.8 phr migrates and reduces adhesion of the waterborne polyurethane lamination applied later. Die-cut foam sheets are laminated to polyester or cotton canvas using a waterborne polyurethane adhesive applied at 30–50 g/m² dry coat weight by a roll coater with a patterned roller. Nip pressure is held at 0.2–0.4 MPa, and the laminate is cured for 24 h at 23 °C and 50 % relative humidity before peel testing. T-peel strength after ISO 11339:2018 is commonly specified above 2.0 N/mm for removable footbeds; if adhesion falls below 1.5 N/mm, corona treatment of 38–42 mN/m surface energy is applied to the foam side.

Finished footbeds for prolonged skin contact must comply with REACH Annex XVII entry 50 regarding polycyclic aromatic hydrocarbons: benzo[a]pyrene must not exceed 1 mg/kg and the sum of eight restricted PAHs must not exceed 10 mg/kg. Since DVR 001A is derived partly from post-industrial EVA footwear scrap, a batch-specific PAH extraction test before production is considered non-negotiable for EU shipments. Published data for this specific calendered configuration using DVR 001A is limited; converters should qualify each incoming lot with a statistically valid pilot run rather than transferring parameters from virgin EVA sheet lines.

Crosslinked Block Skiving and the Relationship Between Gel Content and Skive Blade Temperature

Crosslinked EVA blocks are produced by compression moulding or autoclave expansion, then slit into 0.8–4.0 mm sheets on a horizontal skiving machine. When DVR 001A constitutes 50–70 % of the block compound, the incoming recycled gel content must be measured by ASTM D2765-16 method A before the peroxide cure is specified. If the pre-cure gel fraction exceeds 15 %, the final gel content after 0.6 phr DCP cure can exceed 75 %; at that level the cutting zone temperature rises to 120–140 °C and the skived surface develops fusion tails and irregular thickness. Chilled-air cooling of the blade and a reduced table speed of 0.5–1.0 m/min are used to hold the cutting temperature below 100 °C. The recycled fraction may also contain trace metal particulate from upstream shredding; a 1.0 mm magnetic trap and 0.5 mm stainless steel mesh screen are placed before the internal mixer to protect skiving blades from chattering fractures.

The product range includes orthotic shells, heel lifts, arch pads, and shoe counters that are assembled into orthopedic footwear or sports shoes. For orthotic applications, ISO 10993-5 cytotoxicity and ISO 10993-10 skin irritation data are frequently requested by device assemblers; DVR 001A is not marketed as a medical-grade material, so the final compound must be tested after all additives and lamination steps are fixed. Published data for DVR 001A in ISO 10993 configurations is limited, and biocompatibility cannot be assumed from generic EVA data. Dimensional tolerance on skived sheet is held at ±0.2 mm; below 0.8 mm, the recycled gel fraction increases the reject rate due to blade deflection and surface pull-out.

When Post-Industrial EVA Replaces Virgin Copolymer in High-Tear Protective Mat Foaming

Protective mats, martial-arts flooring, and closed-cell cushioning pads are typically produced at densities from 0.10 g/cm³ to 0.15 g/cm³ with a high tearing strength requirement. DVR 001A is introduced as a partial replacement of 30–50 % of the virgin EVA resin in a blend that may also contain polyolefin elastomer. The compound is mixed in a Banbury internal mixer at 110 °C, dropped at 115 °C, and moved to a two-roll mill at 85–95 °C before azodicarbonamide and dicumyl peroxide are added. The slab preform is cured in a hydraulic press at 160–165 °C and 150 kg/cm²; for parts thicker than 20 mm, the cure cycle uses a slow temperature ramp of 3–4 °C/min to avoid internal scorch. The recycled fraction in DVR 001A can contain metal residues from post-industrial cutting; eddy-current separators and rare-earth magnetic grids of 12,000 gauss are placed upstream of the internal mixer to protect barrel screws and to prevent pinch-point burns during press loading.

Tear strength is tested after ISO 8067:2018, with a minimum specification of 4–6 N/mm for high-use martial-arts mats measured on 2 mm skived test pieces. Compression set after 50 % deflection for 24 h at 23 °C per ISO 1856:2022 is held below 10 % for landing mats. The recycled content may reduce rebound resilience by 2–5 percentage points compared with the same formulation using virgin EVA; resilience is measured on a DIN 53512 rebound pendulum. The mat surface is textured by mould release paper or engraved steel plate, and final mat products are tested for tear propagation and skin-contact PAH compliance under REACH Annex XVII entry 50. Published data for DVR 001A in high-impact sports mats is limited; the above ranges are starting points for pilot-scale trials rather than certified specifications.

Solvent-Free Compression Lamination and Shore C Drift in Orthotic Footbeds

Orthotic footbeds built from a textile top layer, a DVR 001A foam core, and a rubber or TPU bottom layer are assembled by reactive hot-melt compression lamination. The adhesive is a moisture-curing polyurethane applied at 40–60 g/m² with a roll coater at 120–140 °C; open time before pressing is 60–90 s. The stack is pressed at 0.3–0.6 MPa and 50 °C for 30 s, then cold-stabilised at 23 °C for 48 h. The foam core is die-cut from crosslinked sheet at 1.5–2.5 mm thickness, with edge skiving tolerance of ±0.2 mm to prevent visible ridge lines through the top fabric. Because the recycled fraction can exude low-molecular-weight esters and process oils, Shore C values may drift by 2–4 points between demoulding and 7 days of ambient ageing; final hardness is recorded at day 7, not at press time.

Adhesion durability is evaluated by washing cycles in water at 40 °C for 50 cycles followed by T-peel per ISO 11339:2018; the target is retention above 70 % of the original peel strength. For overseas shipments, the moisture content of the foam core before lamination is held below 0.05 % to prevent bubbling under the hot-melt film. The finished footbed is tested for pH and formaldehyde if it is to be sold in direct skin-contact categories; absent a formal EU Ecolabel claim, standard specifications under REACH Annex XVII entry 50 and CPSIA Section 108 still apply when the foam is used in children’s footwear. Because the recycled fraction in DVR 001A originates from multiple footwear production streams, converters must establish incoming lot-specific Shore C, moisture, and PAH profiles; published data for this exact solvent-free lamination configuration is limited, and process windows should not be transferred from one adhesive grade to another without a statistically valid pilot run.