EVAtech 120S/12G EVA Copolymer Compound,Crosslinkable Foam Grade

Compression-molded EVA foam for athletic footwear midsoles is prepared from EVAtech 120S/12G using a two-roll mill at 70-80°C after internal mixing at 100-115°C for 6-8 min. The 12% vinyl acetate comonomer content and melt flow rate of 12 g/10 min at 190°C/2.16 kg permit uniform incorporation of azodicarbonamide at 2.0-3.5 phr and dicumyl peroxide at 0.6-1.0 phr. Zinc stearate at 0.5-1.0 phr and zinc oxide at 0.8-1.2 phr control proton transfer during azodicarbonamide decomposition; calcium carbonate at 5-15 phr acts as a nucleating filler that narrows cell size distribution and reduces shrinkage after demolding. The semi-decomposition temperature of azodicarbonamide is approximately 200-210°C, so the oxide activator system is required to align gas evolution with peroxide cure in the 165-175°C molding window.

Sheet pre-forms are cut to 70-85% of mold volume and compression molded in a hydraulic press at 165-175°C under 10-15 MPa. Cure time is 8-12 min/mm of part thickness. Cooling under pressure to 50°C before demolding prevents uncontrolled post-expansion and surface blistering. The resulting closed-cell foam exhibits apparent density of 0.15-0.25 g/cm³ when tested per ISO 845:2006, Asker C hardness of 45-60, and compression set below 30% after 22 h at 70°C per ASTM D3575-20. Terminal products include running shoe midsoles, court-shoe wedges, and women's platform soles where density and hardness gradients are achieved by varying blowing agent ratio and mold fill percentage.

Roll-stock foaming for heat-sealable gasket sheeting uses EVAtech 120S/12G with azodicarbonamide reduced to 1.5-2.5 phr to maintain skin integrity and permit die-cutting of closed-cell rolls at 3-10 mm thickness. The compound is mixed in an internal mixer at 95-105°C, then calendered to a pre-sheet thickness of 1.5-2.5 mm. Continuous foaming is conducted in a hot-air oven at 220-240°C for 3-6 min; the sheet expands to 5-10 mm after crosslinking. For compression-molded slabstock, a multi-daylight press at 150-160°C with dwell of 20-30 min is used for thicknesses up to 50 mm.

Closed-cell content above 90% when tested per ASTM D1056-14 qualifies the foamed sheet for HVAC flange gaskets and expansion joint filler. Density and compression deflection are controlled per ASTM D1667-17. Thermal conductivity of closed-cell EVA sheet is typically 0.038-0.045 W/m·K at 25°C, measured by ASTM C518-17, which supports use as thermal break strips around window and door frames. The material is heat-sealable to itself and to polyethylene film, but adhesion to polypropylene requires surface corona treatment at 38-42 dyne/cm.

What Limits Blowing Agent Efficiency in Thick-Section Marine Foam?

In thick-section marine foam slabs above 80 mm, the limiting parameter is not crosslink density but internal exotherm and outgassing path length. EVAtech 120S/12G is formulated with dicumyl peroxide at 0.5-0.8 phr and azodicarbonamide at 2.5-4.0 phr; the peroxide cure exotherm and azodicarbonamide decomposition peak at approximately 205°C create a cure/gas-generation mismatch when the slab center remains above 190°C after mold surfaces begin cooling. This mismatch causes irregular cell coalescence, internal splits, and density gradients exceeding 15% between core and skin. Transfer molding of marine fender cores therefore requires mold temperatures of 155-165°C, pressure of 4-6 MPa, and a step-cure profile with an intermediate hold at 135°C for 15 min before final cure at 165°C for 20 min.

Closed-cell water absorption below 3% by volume per ASTM D3575-20 is required for marine fender and buoyancy applications. The material is not to be combined with amine-based antioxidants because amine hydrogen donation scavenges peroxide radicals and depresses gel fraction below 70%, which raises water vapor transmission and long-term compression set. For life preserver foam, compliance with 46 CFR 160.064 requires separate certification testing; published data for this specific configuration is limited and must be generated per production batch. Terminal products include mooring fenders, floating dock blocks, and buoyancy billets for marine structures.

When EVA Foam Replaces Polyurethane in Automotive Interior Padding

When EVA foam replaces polyurethane in automotive interior padding, the primary process change is the need for compression-molded skin formation rather than liquid reaction injection molding. EVAtech 120S/12G is compounded with 2.0-3.0 phr azodicarbonamide and 0.7-1.0 phr dicumyl peroxide, then compression molded at 160-170°C to density 0.08-0.15 g/cm³. A 2-4 mm integral skin is achieved by cooling mold surfaces to 80°C before decompression. Volatile organic compound and fogging performance is controlled by selecting paraffinic processing oil below 5 phr and by post-curing at 90°C for 4 h. Testing per VDA 278 should confirm total volatile organic compounds below 100 µg/g and fog condensate below 250 µg/g for automotive interior acceptance.

Flammability testing per FMVSS 302 requires burn rate below 100 mm/min; typical closed-cell EVA foam passes with a phosphorus-based intumescent package at 5-8 phr. Compression set is limited to below 30% at 50% deflection after 22 h at 70°C per ASTM D3575-20. REACH Annex XVII restricted substances and RoHS Directive 2011/65/EU limits of lead below 1000 ppm and cadmium below 100 ppm should be verified by X-ray fluorescence screening on each raw material lot. Terminal products include dashboard pads, door panel bolsters, headliner edge strips, and A-pillar trim.

High-resilience sports mat slabs are manufactured from EVAtech 120S/12G by compression molding in a multi-daylight press with 20-50 mm cavity depth. The formulation uses 3.0-5.0 phr azodicarbonamide for low density of 0.06-0.12 g/cm³ and 0.4-0.7 phr dicumyl peroxide to maintain elongation at break above 150% per ISO 1798:2008. Calcium carbonate is limited to 5 phr because higher filler loadings reduce tear strength below 2.5 N/mm. Pre-heating at 120°C for 10 min before press cure at 165°C under 8-12 MPa reduces density variation across a 1 m × 2 m slab to below 5%. Demolding at 50°C prevents surface collapse and uneven skin thickness.

For martial arts and gymnastics mats, shock absorption is measured per ASTM F355-16; peak acceleration below 50 g meets many institutional flooring specifications. REACH Annex XVII requires phthalate plasticizers below 0.1% for child-contact mats; EVAtech 120S/12G is formulated without ortho-phthalates. The closed-cell surface resists perspiration absorption, but repeated cleaning with hydrogen peroxide at concentrations above 3% can oxidize the surface and increase slip resistance only in early service life. Terminal products include martial arts mats, yoga mats, gym floor underlayment, and anti-fatigue standing mats.

Compression Set After Moisture Ageing in Orthotic Cushioning

Orthotic cushioning fabricated from EVAtech 120S/12G must demonstrate stable compression set after moisture ageing because in-shoe humidity typically reaches 80-95% RH at 32-37°C. Closed-cell foams are compounded with 0.8-1.2 phr dicumyl peroxide and 2.0-2.8 phr azodicarbonamide to produce density of 0.12-0.18 g/cm³ and compression set below 45% after 22 h at 70°C per ASTM D3575-20. Sheet molding at 155-165°C with 10-14 MPa and 15-20 min cure yields 30-40 Shore A material. Post-cure conditioning at 60°C for 24 h reduces residual peroxide breakdown products that can cause skin sensitization.

Cytotoxicity testing per ISO 10993-5 and sensitization per ISO 10993-10 are required when the foam contacts skin over prolonged periods; published data for this specific configuration is limited and must be generated per production batch. The material is not intended for direct wound contact or for long-term implanted use. Terminal products include diabetic footbed top sheets, ankle-foot orthosis interface padding, metatarsal pads, and heel cushions where moisture-stable compression set and low density are primary acceptance criteria.

Electronics cushion packaging made from EVAtech 120S/12G is designed for single-impact and vibration attenuation rather than electrostatic discharge protection; the unfilled compound is an insulator with surface resistivity above 10^12 Ω/sq per IEC 61340-5-1. When electrostatic discharge protection is required, the foam is laminated with antistatic film or the compound is modified with conductive carbon black at 5-15 phr, which raises density and reduces resilience. Open-mold compression foaming at 150-160°C with 2.0-2.5 phr azodicarbonamide and 0.5-0.7 phr dicumyl peroxide produces die-cut inserts at density of 0.15-0.20 g/cm³. Damping and distribution cycle performance are measured per ASTM D3575-20 and ASTM D4169-22.

REACH Annex XVII restricted substance compliance is required for packaging placed on the EU market. RoHS Directive 2011/65/EU applies to electrical equipment rather than packaging, but brand specifications commonly require absence of lead and cadmium below 100 ppm by X-ray fluorescence screening. Terminal products include hard-drive cradle inserts, circuit board corner supports, lens shipping pads, and precision instrument cushioning sets where dimensional recovery after compression is more important than high resilience.

Low-Density Protective Padding and the Role of Nucleation Control

Low-density protective padding for shoulder pads and knee protectors requires cell size below 0.5 mm to distribute impact energy uniformly. Nucleation control is achieved by adding 0.5-1.5 phr micronized calcium carbonate or 0.2-0.5 phr talc to EVAtech 120S/12G before blending with 3.0-4.0 phr azodicarbonamide and 0.6-0.9 phr dicumyl peroxide. Injection molding of protective pads uses screw L/D ratio of 22:1 to 26:1, barrel temperatures of 80-110°C, and mold temperatures of 140-160°C. The mold is partially filled to 60-75% volumetric fill to allow foam expansion, and injection speed is kept below 40 mm/s to prevent premature shear heating above the dicumyl peroxide decomposition temperature.

Impact attenuation is measured per EN 1621-1 for limb protectors; mean transmitted force below 35 kN is a common benchmark for Type A protectors. The foam is closed-cell, so water absorption in service remains below 2% by volume per ASTM D3575-20. Operational boundaries include the use of non-amine release agents and avoidance of direct contact with hydrocarbon solvents, which swell the vinyl acetate phase and reduce compression set recovery. Terminal products include shoulder, elbow, knee, and hip protective pads for sports and occupational protective garments.