Celanese UHMW-PE 4022 ECO-B is an ultra-high-molecular-weight polyethylene powder supplied as a bio-attributed grade through a mass-balance allocation. The base resin is a homopolymer with a nominal molecular weight of 4.0 × 10⁶ g/mol; because the melt does not flow under standard melt-flow test conditions, the grade is specified by solution viscosity in ISO 1628-3 rather than by melt flow rate. The material is intended for ram extrusion and compression moulding of wear parts, guide rails, bearing segments, chain wear strips, star wheels, and hopper linings. Compression-moulded sheet from this grade is characterised by density in the 0.930–0.940 g/cm³ range under ISO 1183-1, tensile yield stress in the 20–22 MPa range under ISO 527-2, and double-notched Charpy impact behaviour that produces no break at 23°C under ISO 11542-2. The ECO-B designation does not denote a polymer composition change; it indicates bio-circular or renewable feedstock accounting assigned to the ethylene stream.

Does the Bio-Attributed Feedstock Alter the Sintering Window of UHMW-PE 4022?

Differential scanning calorimetry under ISO 11357-3 places the crystalline melting peak between 130°C and 135°C. The bio-attributed monomer does not shift this peak because the polymer backbone is identical to fossil-based polyethylene. Sintering in ram extrusion and compression moulding requires plate or barrel temperatures of 190°C to 220°C. Below 190°C, interparticle diffusion is incomplete and a white, porous core is observed in sections greater than 40 mm. Above 220°C, oxidative chain scission dominates; published oxidation induction time data for this specific ECO-B configuration is limited, so end users should run ISO 11357-6 OIT verification on incoming powder batches. The powder particle size distribution influences sintering uniformity. Laser diffraction data for the 4022 series typically show a median particle size of 120–180 µm, with fines below 63 µm controlled to maintain hopper flow. The bio-attributed grade is blended to the same particle-size specification as fossil 4022, which permits direct replacement on existing production lines without altering compaction ratio or feed auger geometry.

When Ram Extruder Barrel Temperatures Exceed 230°C in Production

On single-ram extruders with 50–120 mm barrel diameters and effective length-to-diameter ratios of 20:1 to 30:1, the barrel is divided into feeding, compaction, and sintering zones. The powder is compacted at room temperature, then sintered in a heated die land. Industrial machine set-points are usually 180°C to 230°C. If the sintering zone exceeds 230°C for more than 20 min, the surface of the extrudate develops yellowing and melt fracture, and the elongation at break measured on the finished profile can fall below 200%. The process window around the optimum set-point is typically ±5°C. Throughput is controlled by cycle rate and back-pressure rather than screw speed. On a 63 mm single-ram machine, profiles with cross-sections between 500 mm² and 3 000 mm² typically run at 5–15 kg/h. Feed bridging occurs when powder bulk density falls outside 0.40–0.45 g/cm³; vibratory hoppers and storage at 20–25°C are used to maintain consistent flow. Condensation on cold powder exposed to relative humidity above 60% can create steam pitting in the sintered product, so pre-conditioning of the powder is specified when silo discharge temperature is below the dew point.

The following values are representative of compression-moulded sheet produced from 4022 ECO-B; they are not batch-level specification limits.

The crystalline superstructure of 4022 ECO-B after slow cooling produces a Shore D hardness of 60–65. The polymer has a dynamic coefficient of friction against polished steel of approximately 0.10–0.20 under dry sliding conditions; the coefficient rises when wet or when stainless steel is replaced with carbon steel. In sand-slurry abrasion testing under ISO 15527, UHMW-PE grades of this molecular weight generally exhibit volume loss between 75 mm³ and 100 mm³, but the exact value depends on abrasive particle angularity and test duration. The ECO-B bio-attribution does not alter the crystalline lamellar thickness or the wear mechanism, which is micro-ploughing and fatigue delamination. On production lines, the wear rate of 4022 ECO-B guide rails is highest during the first 50 h of operation as the surface skin is removed, after which the wear rate stabilises. This burn-in behaviour is identical to fossil 4022 and should be accounted for in dimensional inspection schedules.

Comparative Abrasion and Impact Data Against Higher-Molecular-Weight GUR Grades

Compared with fossil-based 4022, the ECO-B grade exhibits no statistically measurable shift in tensile yield stress, Shore D hardness, or double-notched Charpy impact. The bio-attribution is an accounting property, not a mechanical one. Compared with lower-molecular-weight UHMW-PE grades intended for screw plasticating and injection moulding, 4022 ECO-B has higher abrasion resistance and higher impact toughness but cannot be injected because the melt viscosity is outside the range of conventional injection units. Compared with higher-molecular-weight GUR grades such as GUR 4150, 4022 ECO-B shows a lower sintering viscosity, which improves core consolidation in thick sections above 80 mm; the trade-off is a slightly lower three-body abrasion resistance under ISO 15527 sand-slurry conditions. Published data for this specific grade configuration is limited, but the relative ranking of molecular weight and slurry wear resistance is consistent with the UHMW-PE literature. A direct replacement of fossil 4022 with 4022 ECO-B on a ram extrusion line does not require tooling changes or new temperature profiles when bulk density and particle-size distribution are within the same specification band.

Machining of 4022 ECO-B sheet and rod is performed with carbide or polycrystalline diamond tooling at surface speeds of 200–400 m/min, with air cooling to prevent local melting. Thermal expansion is approximately 1.5 × 10⁻⁴ K⁻¹, roughly one order of magnitude higher than structural steel; bearing clearances must be designed to accommodate this movement. Creep under load occurs at room temperature, so clamping forces should be distributed over large washers or metal backup plates.

The Mass-Balance Certificate Applies to the Feedstock, Not to the Polymer Backbone

The ECO-B grade is positioned within an ISCC PLUS-certified mass-balance accounting framework. Renewable or bio-circular feedstock is allocated to the ethylene cracker, and the attribution is transferred to the polyethylene powder. The final polymer is not necessarily composed molecule-for-molecule of renewable-carbon monomers; the mass-balance system assigns a defined portion of the output to the bio-attributed product. Under REACH, polyethylene is exempt from polymer registration under Article 2(9), while monomers and additives must be registered. The grade is typically below the maximum concentration values in RoHS 2011/65/EU for lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE when unfilled. Food-contact suitability must be verified by the converter against 21 CFR 177.1520 or EU 10/2011; the ECO-B designation does not automatically confer food-contact status. The bio-attributed feedstock should not be confused with biodegradability; UHMW-PE 4022 ECO-B is not biodegradable under ambient or marine conditions.

Compression moulding of 4022 ECO-B requires platens heated to 190–210°C, consolidation pressure of 5–10 MPa on the projected part area, and controlled cooling below 0.5 K/min through the crystallisation range from 120°C to 80°C. Cooling too rapidly produces warpage and residual stress. Thick-section parts above 100 mm require extended dwell to avoid core porosity, but residence times longer than 30 min at 220°C should be avoided because chain degradation reduces elongation at break. Conventional single-screw plasticating extruders are not suitable for this grade; the powder does not form a continuous melt pump, and screw friction can generate local temperatures above 280°C. Pigments and fillers such as graphite, carbon black, or glass powder can be dry-blended before sintering at loadings up to 10 wt%, but their presence increases internal friction and lowers double-notched Charpy impact. Amine-based additives and metal stearates are not required for this polyolefin and can exude to die surfaces during long ram-extrusion runs; they should be avoided unless supported by compatibility data.