Celanese UHMW-PE 4056-3 is a high-molar-mass ultra-high-molecular-weight polyethylene (PE-UHMW) grade within the GUR portfolio. The numerical designation identifies a nominal average molecular weight of approximately 5.6 × 10⁶ g/mol, although the current Celanese technical datasheet remains the governing source for lot-specific values. The product is supplied as powder or consolidated stock for compression moulding, ram extrusion, and machining. In common with PE-UHMW grades classified under ASTM D4020 and ISO 21304-1, the material does not produce a meaningful melt mass-flow rate under ISO 1133-1:2022 because the high molar mass and chain entanglement prevent standard piston flow. Typical PE-UHMW homopolymer performance includes a density between 0.930 g/cm³ and 0.945 g/cm³ measured by ISO 1183-1. The crystalline melting peak is observed between 130 °C and 136 °C by differential scanning calorimetry per ISO 11357-3. Because the grade is intentionally high-molecular-weight, conventional melt flow data are replaced by solution viscosity number according to ISO 1628-3 as a release parameter. Batch-to-batch variation in powder bulk density and viscosity number can influence consolidation behaviour; production lots with lower bulk density often require tighter feed control on ram extrusion lines to prevent bridging. Published data for this specific grade configuration is more limited than for commodity HDPE. The values cited in this document are representative PE-UHMW ranges and must be verified against the current Celanese certificate of analysis before design.

Which physical property thresholds define the 4056-3 grade?

For most wear and structural applications, the material is specified against the property set below. The table presents representative ranges for PE-UHMW 4056-3 under standard specimen preparation. These values are not absolute design allowables because machined-part performance depends on stock shape, fusion quality, and machining-induced surface damage.

Property	Test method	Representative range
Density	ISO 1183-1 / ASTM D792	0.930–0.945 g/cm³
Tensile yield stress	ISO 527-2 / ASTM D638-14	21–28 MPa
Tensile elongation at break	ISO 527-2 / ASTM D638-14	>300 %
Notched Izod impact	ASTM D256	no break
Shore D hardness	ISO 868 / ASTM D2240	60–70
Vicat softening temperature A50	ISO 306 / ASTM D1525	80–85 °C
Water absorption 24 h	ASTM D570	<0.01 %

Creep and wear performance are not captured by short-term tensile data. For continuous load-bearing applications above 60 °C, creep modulus can decline rapidly; design calculations should use creep-rupture data generated on the fabricated form rather than room-temperature tensile properties. Processing the high-viscosity powder requires positive pressure and sufficient time at temperature to achieve chain interdiffusion across particle boundaries. Compression moulding is typically performed at 10–20 MPa and 190–220 °C, with hold times extended to 30–60 min for thick sections to avoid incomplete fusion. Cooling under pressure to below 60 °C before demoulding reduces warpage and residual stress. Insufficient pressure or a heating ramp below 180 °C produces powder-grain boundary defects that appear as chalky, low-impact fracture surfaces. Ram extrusion of rod and sheet uses barrel temperatures between 180 °C and 220 °C; the die temperature is often maintained slightly above the crystalline melting point to control melt fracture. Production ram extruders for high-molar-mass grades frequently operate below 0.1 m/min; higher pull rates increase axial residual stress and centreline porosity. Pre-drying at 80 °C for 2–4 h is applied when ambient relative humidity exceeds 60 % because adsorbed moisture can form microvoids during consolidation. Conventional single-screw extrusion is generally avoided for 4056-3; published data for continuous screw plastication of this exact grade is limited. Cold pre-compaction at 5–10 MPa prior to heating improves powder contact and reduces trapped air in thick sections. For compression moulding presses, platen temperature uniformity should be maintained within ±3 °C across the part; larger platens with uneven heating can produce differential crystallinity and warpage. Production-scale empirical checks include visual inspection of machined surfaces for chalky zones and notched impact testing of coupons cut from the centre of thick sections. Machining of 4056-3 stock produces discontinuous chips; tool geometry should use high positive rake and generous clearance to reduce melt smearing. Dimensional control is complicated by a coefficient of linear thermal expansion near 1.5 × 10⁻⁴ K⁻¹; parts machined at elevated temperature can shift in size after cooling.

Melt viscosity and grade-to-grade variation within the GUR portfolio

Relative to lower-molecular-weight PE-UHMW grades such as GUR 4120 and GUR 4022, the 4056-3 grade has a longer reptation time for chain interdiffusion, which scales approximately with molar mass to the 3.4 power. This molecular-weight difference is the principal source of processing conflict: higher hardness and abrasion resistance require higher molar mass, but higher molar mass reduces molecular mobility and increases required moulding hold time. The numeric designation of GUR 4120 corresponds to approximately 1.2 × 10⁶ g/mol, GUR 4022 to approximately 2.2 × 10⁶ g/mol, and 4056-3 to approximately 5.6 × 10⁶ g/mol. These are grade-class identifiers rather than measured molecular weights. In the sand-slurry abrasion test of ISO 15527, higher-molar-mass PE-UHMW grades typically show lower volume loss than lower-MW grades; actual values depend on slurry velocity, particle angularity, and test temperature. Published data for this specific configuration is limited, so comparative wear screening should be performed against the candidate replacement grade in the same fixture. The solution viscosity number measured by ISO 1628-3 is the most reliable release parameter for differentiating grades. When raw powder changes from lower-MW to higher-MW material, ram extrusion lines often require a reduction in pull rate and an increase in heating zone residence time. Batch-to-batch variance in solution viscosity number and powder bulk density can shift the processing window by several degrees; production personnel typically monitor motor load and dimensional swell to adjust the feed rate. Sliding-wear and impact applications make use of the combination of low dry-sliding friction and high notched impact strength. Pin-on-disc testing per ASTM G99 against polished steel commonly places the dynamic coefficient of friction between 0.10 and 0.25, depending on surface finish, sliding velocity, and contact pressure. The static coefficient can be higher, particularly at low speeds. The grade is therefore specified for chain guides, wear strips, star wheels, conveyor idlers, buffer pads, and hopper liners where impact loads accompany abrasive sliding. The high molar mass of 4056-3 shifts the ductile-to-brittle transition toward lower temperatures; notched Izod specimens prepared per ASTM D256 often report no break at -196 °C. This characteristic differentiates the material from HDPE, which can exhibit brittle fracture under the same conditions. HDPE notched Izod impact per ASTM D256 typically falls between 100 J/m and 200 J/m; the same test on well-fused PE-UHMW 4056-3 usually records no break. The impact result is strongly dependent on fusion quality and notching practice; machined corners and sharp chamfers act as stress concentrators and may reduce component-level impact performance below the datasheet value. Surface finish of fabricated stock is controlled to Ra 0.8 µm or lower for dynamic seal rails and wear guides. Rougher surfaces increase initial wear debris generation and can elevate steady-state wear rate during the bedding-in period. Oxidative degradation is monitored by oxidation induction time per ISO 11357-6; a reduction from the virgin-powder value indicates stabilizer depletion in reclaimed material.

When 4056-3 replaces HDPE or PTFE in sliding-wear service

When 4056-3 replaces HDPE in chilled or abrasive service, the primary benefit is a reduction in abrasive wear rate and improved low-temperature impact resistance. The trade-off is a longer consolidation cycle and reduced melt processability. When the replacement targets PTFE, the coefficient of friction is higher than PTFE; however, PE-UHMW often exhibits higher wear resistance under high-load or particle-contaminated conditions. Direct one-to-one substitution without clearance modification can fail because PE-UHMW has a higher thermal expansion coefficient than steel, near 1.5 × 10⁻⁴ K⁻¹ per ASTM D696; running clearances must be adjusted to avoid seizure at elevated temperature. The maximum continuous service temperature under load is lower than PTFE. Creep resistance above 90 °C is limited; PTFE remains more suitable for non-lubricated sliding at elevated temperature unless a filled PE-UHMW is qualified. In addition, 4056-3 is not intended for continuous exposure to strong oxidizing acids, chlorine gas, or aromatic hydrocarbons at elevated temperatures, which can cause environmental stress cracking or oxidative embrittlement. Regulatory compliance for 4056-3 depends on the specific lot, the conversion process, and any added stabilizers or processing aids. PE-UHMW homopolymers in this family may be formulated to meet FDA 21 CFR 177.1520 for food-contact olefin polymers, provided that end-use extraction testing is completed on the finished article. The material is subject to REACH Regulation (EC) No 1907/2006 and RoHS Directive 2011/65/EU; absence of halogenated flame retardants and heavy metals must be confirmed against the safety data sheet. For medical device use, ASTM F648 applies only to implant-grade PE-UHMW powder and fabricated forms; the 4056-3 grade should not be assumed to meet implant specifications without a dedicated qualification under ISO 10993-1. Biocompatibility assessment under ISO 10993-1 includes cytotoxicity per ISO 10993-5, sensitization per ISO 10993-10, and irritation per ISO 10993-23 where applicable. These tests are performed on the final device, not on raw resin.

Scope	Standard/regulation	Applicability
Food contact	FDA 21 CFR 177.1520	Lot-specific; extraction testing required
EU chemical registration	REACH (EC) No 1907/2006	Substance/import compliance
RoHS	Directive 2011/65/EU	Certified absence of restricted substances
General classification	ASTM D4020 / ISO 21304-1	PE-UHMW material specification
Surgical implant	ASTM F648 / ISO 10993-1	Only if dedicated grade; not assumed