Where dry-running chain speeds exceed 0.8 m/s and stainless steel link plates abrade polyamide 6 guide rails to a replacement interval below 1,200 h, maintenance engineers evaluate ram-extruded profiles from Celanese GUR UHMWPE 4022. The powder does not exhibit measurable melt mass-flow rate under ISO 1133-1:2022 at 190°C/21.6 kg; viscosity number determined by ISO 1628-3 typically exceeds 2,000 ml/g. Ram extrusion is therefore used instead of screw plasticization. The powder is precompacted in the feed zone at 15–30 MPa by a hydraulic ram and pushed through an oil-jacketed die body held at 180–220°C with a die land length of 250–500 mm. Unlike single-screw extrusion, the process does not rely on shear heating; wall adhesion, precompaction density, and die temperature control define interparticle fusion. Batch-to-batch bulk density variation from 0.42 g/cm³ to 0.47 g/cm³ alters feed bed compression and can shift profile density by ±0.5%; feed hoppers with gravimetric control and deaeration are therefore specified. Formulation remains 100 phr GUR 4022 with 0 phr plasticizer; where outdoor UV exposure is specified, 2.0–2.5 wt% carbon black masterbatch is introduced, but addition above 3.0 wt% produces die lip plate-out and weak interparticle fusion at the profile core. Material specification is governed by ASTM D4020-18 and ISO 11542-1:2001; RoHS 2011/65/EU and REACH SVHC documentation apply to shipped profiles. Downstream profile blanks are milled into chain guides, wear strips, star wheels, belt scrapers, and bottle-handling change parts. Re-grind of post-industrial skeletons is limited to 10 wt% and only with sieve control below 300 µm because larger particles disrupt ram packing and create surface porosity.

What Governs Solvent Retention and Draw Resonance in GUR 4022 Gel Spinning?

In gel spinning, GUR 4022 is not melt-processed but dissolved in 90–95 wt% decahydronaphthalene or mineral oil to form a solution containing 5–10 wt% polymer. The solution is prepared under nitrogen at 130–170°C and delivered to a single-screw or twin-screw extruder with L/D 25–40, then extruded through a spinneret capillary diameter of 0.5–1.0 mm. Solution concentration below 4 wt% yields as-spun gel filament with insufficient entanglement to survive extraction; above 12 wt% gelation inside the extruder creates pressure fluctuations exceeding ±0.5 MPa and spinneret blocking. After quenching at 0–15°C, the gel fibre is extracted and drawn 20–60× in a multi-stage hot draw stand at 120–150°C; residual solvent above 0.2 wt% causes draw-induced voids and reduces yarn tenacity. Formulation addition includes 0.05–0.1 wt% hindered phenol antioxidant per polymer mass; above 0.2 wt% antioxidant raises solution viscosity and die pressure without commensurate long-term thermal gain. Yarn tensile is evaluated per ASTM D885/D885M-10A; finished ballistic panels are assessed per NIJ Standard 0101.06; marine rope testing follows EN ISO 2307. High-tenacity yarns, cut-resistant glove filaments, marine mooring ropes, unidirectional protective laminates, and spall liners are the principal terminal stock-keeping units. Production-scale failure modes include draw resonance at the first godet pair when speed ratio exceeds 6:1 and residual solvent pockets that cause filament splitting during hot drawing.

In the plasticizer-extraction wet process for lithium-ion battery separator film, GUR 4022 powder is metered into 70–85 wt% paraffin oil at 140–170°C to reach 15–30 wt% polymer concentration. The formulation window is narrow: below 15 wt% polymer the cast gel film necks during biaxial stretching, and above 30 wt% the melt pressure at the T-die exceeds 8 MPa and gel particle formation creates pinholes after extraction. Optional silica at 5–10 wt% of polymer mass serves as pore morphology modifier; it raises the Gurley air resistance measured by JIS P 8117 and modifies shutdown response in the finished separator. The gel film is cast through a T-die of width 300–1,200 mm onto a chill roll at 10–30°C, then biaxially stretched in a sequential stretcher at 90–120°C with MD ratio 4–7 and TD ratio 4–7. Plasticizer is extracted in methylene chloride or n-hexane to residual oil below 0.2 wt%, followed by annealing at 110–130°C to relax orientation and set shrinkage below 3% at 90°C/30 min. Film tensile is measured per ASTM D882-18; thickness per ASTM D5947-18; finished cells per UL 1642, IEC 62133-2:2017, and transport per UN 38.3. Separator rolls for cylindrical, prismatic and pouch lithium-ion cells are produced in thickness 5–25 µm and slit width 30–1,000 mm; pinhole density is monitored by vision systems at ≤1 pinhole/m² for high-speed winding. Gel specks larger than 0.1 mm are rejected because they create local thickness spikes and cell voltage instability.

Compression Moulding Parameter Window for Thick Cross-Section GUR 4022 Stock

Compression moulding of slab stock uses hydraulic presses with platen parallelism ≤ 0.05 mm per metre and oil-heated platens. The mould cavity is filled with GUR 4022 powder at a fill factor of 2.5–3.0, cold-compacted at 5 MPa for deaeration, then heated to 200–220°C. Pressure is raised to 10–20 MPa and held for 20–40 min depending on thickness; cooling is conducted at 5–10 K/min under pressure until the core reaches 60°C or below. Demoulding above 60°C produces convex warpage exceeding 2 mm/m due to residual internal stress. The formulation is 100 phr GUR 4022; 0.1–0.3 wt% calcium stearate may be added as mould release, while antioxidant loadings are kept below 0.2 wt% to avoid lowering interparticle fusion. Test specimens are prepared per ISO 11542-2:1998, and the resin is specified under ASTM D4020-18. Food-contact stock requires compliance with 21 CFR 177.1520 and EU 10/2011. Parts above 120 mm thickness require multi-stage heating and cooling to prevent core voids. Downstream machining produces pump vanes, scraper blades, chain guide blocks, chute liners, and filter press wear components.

When Sintering Pressure Is Lowered Below Full Densification

Porous sintered stock is produced by loading GUR 4022 powder into a closed mould and applying only 2–5 MPa at 170–190°C for 10–25 min; full density is suppressed because interparticle fusion occurs at contact points without complete void elimination. Pore size is controlled by powder sieve cut and compression force; for pores above 10 µm, 20–40 wt% sieved sodium chloride porogen is blended with the powder and removed by water leaching after sintering. Bubble point is evaluated per ISO 2942:2018, and multi-pass filter performance per ISO 16889:2022. End products include wastewater aeration discs, pneumatic exhaust silencers, suction box covers for paper machines, and low-load filter elements. Published data for GUR 4022 in this specific porous configuration is limited; sintering conditions must be validated on the target hydraulic press due to batch-to-batch bulk density differences and porous structure sensitivity to ±2 MPa pressure shifts.

In bakeries and confectionery lines where stainless steel scrapers score polyethylene liners and create biofilm retention points, GUR 4022 machined scrapers are installed after verification of compliance with 21 CFR 177.1520 and EU 10/2011; the stock is compression moulded per ISO 11542-2, CNC-machined, and planed or flame-polished to surface fissures below 0.8 µm Ra, the formulation is 100 phr virgin GUR 4022 without regrind, and where foreign-body detection is required, 0.5–1.0 wt% metal-detectable additive is used, with end products including dough scrapers, guide blocks, feed screws, and scraper blades for continuous ovens, while continuous service temperature is limited to 80°C due to dimensional creep under load.