On outside-plant fibre-optic cable lines, LyondellBasell HDPE M5370WC W&C is applied as the outer sheath over dielectric or metallic strength members and water-blocked loose-tube cores. Extruder configuration is a single-screw polyethylene machine with a grooved feed section, an L/D ratio of 30:1 to 33:1, and a barrier screw with a Maddock mixing section. Barrel setpoints are held at 190 °C to 225 °C; adapter and head zones are set 10 °C to 20 °C higher; melt temperature at the crosshead is maintained between 225 °C and 250 °C. Pressure tooling is used to fill the core interstices, with drawdown ratio limited to 1.5:1 to 2.0:1 because higher drawdown introduces the orientation that later appears as jacket shrinkback. The screen pack is 80/120/80 mesh; a pressure rise of more than 50 bar across the pack indicates carbon black agglomeration or a breached screen and triggers a line stop. Cooling is a multi-stage water trough with first-stage water at 25 °C to 40 °C and final-stage water at 10 °C to 20 °C to anneal the amorphous phase before the crystalline fraction locks in. The black compound requires no colour concentrate, and no drying is needed unless the granulate has been stored at relative humidity above 60%, in which case 70 °C for 2 h prevents surface porosity. Finished products are buried and aerial fibre-to-the-home drop cables with jacket wall thickness from 0.8 mm to 2.0 mm, where the sheath must pass outdoor exposure criteria under IEC 60794-1-2 and survive plowing, rock contact, soil pH variation, and longitudinal water migration.

Is shrinkback or abrasion loss the first failure mode in loose-tube cable jackets?

When a cable specification invokes IEC 60794-1-2 or Telcordia GR-20-CORE, jacket shrinkback is measured after oven aging at 100 °C for 1 h; the pass criterion is commonly not more than 5 mm of retraction on a marked 150 mm jacket specimen. The residual orientation introduced by high drawdown—especially above 2.5:1—is the main cause of post-installation shrinkback in HDPE jackets. On lines where LyondellBasell HDPE M5370WC W&C is processed for loose-tube cables, drawdown is therefore held below 2.0:1, and the first cooling trough is run at an elevated temperature to reduce frozen-in stress before final cooling. The carbon black loading contributes to ultraviolet opacity but does not control shrinkback; the governing variables are extrusion shear history, drawdown, and cooling gradient. Abrasion resistance, by contrast, is assessed at cable level through the sand/slurry or pin-abrasion method in IEC 60794-1-2. The terminal product is an aerial or buried loose-tube cable in which the sheath must retain fibre containment, prevent water ingress at closure trays, and resist rocky soil abrasion without exposing the core to moisture.

Inside the coaxial drop cable segment, LyondellBasell HDPE M5370WC W&C is applied as a black outer jacket over aluminium-polyester foil and tinned copper braid. The line speed is typically between 80 m/min and 200 m/min, and the jacket is applied by pressure extrusion over the shield; because the jacket is not the primary dielectric, the carbon black in the compound does not affect signal attenuation. The main processing variable is adhesion to the foil shield—if melt temperature falls below 215 °C, the polyethylene may not wet the foil surface sufficiently to prevent moisture ingress at the shield overlap, while melt temperatures above 260 °C increase surface oxidation and odour generation. The compound is not hygroscopic, but high-humidity storage can produce pinholes if condensation is drawn into the feed throat. Finished products are outdoor CATV drop cables and distribution cables where the jacket must withstand ultraviolet exposure, branch abrasion, clamp compression, and repeated flexing at low service temperatures; the cable is not load-bearing and relies on a separate steel messenger where aerial installation is specified.

Copper drop wire jacketing and the control of oxidative metal contact

Copper telephone drop wire and block cable constructions employ LyondellBasell HDPE M5370WC W&C as an abrasion-resistant outer jacket over solid copper conductors and polyolefin insulation. The jacket compound is carbon black filled and is not intended to function as a low-loss dielectric; in direct contact with copper, unstabilised HDPE can undergo copper-catalysed thermo-oxidative degradation at temperatures above 150 °C, so the conductor is isolated by a non-conductive insulation layer before the jacket is applied. The extrusion line for this segment commonly uses a 60 mm to 90 mm single-screw extruder with a dual-head crosshead to apply insulation and jacket in tandem. Jacket thickness is generally 1.0 mm to 1.5 mm, and the jacket is sampled for tensile elongation after conditioning according to ASTM D638-14. The terminal product is a buried or aerial service drop where the jacket provides water and soil-chemical isolation and mechanical protection during installation and service.

For low-voltage industrial signal and control cables installed in chemical plants, HDPE jacketing is selected when the environment contains mineral acids, aliphatic hydrocarbons, or aggressive soil. The thermal limit is specific: HDPE jacketing is restricted to continuous conductor temperatures below 75 °C, so it is not applied to power circuits requiring high current ratings. In this segment, LyondellBasell HDPE M5370WC W&C is extruded as an outer sheath over shielded twisted-pair or multicore constructions, using the same pressure tooling as telecom cables but with a wall thickness increased to 1.5 mm to 2.5 mm for mechanical protection. Chemical resistance is evaluated against ASTM D543 immersion tests; oil resistance of sheathing is evaluated under IEC 60811-404. Published data for this specific compound under strong oxidising acids is limited, so qualification testing is required before an order is placed for such exposure. The terminal product is a junction-box or cable-tray signal cable where the HDPE sheath excludes water, resists aliphatic hydrocarbon splashes, and reduces maintenance replacement frequency compared with plasticised PVC compounds.

When low surface friction is required for air-blown fibre installation

When outside-plant cable is installed by air blowing into pre-installed HDPE ducts, the dynamic coefficient of friction between the jacket and duct determines the maximum blowing distance. LyondellBasell HDPE M5370WC W&C offers an HDPE-to-HDPE contact pair with lower drag than PVC or low-smoke zero-halogen jackets, but surface smoothness is process-dependent. A polished die land, melt temperature above 225 °C, and absence of moisture in the feed throat prevent surface roughness from die-lip deposits. On-line surface lubricants should not be added unless approved because they alter blowing friction and can contaminate the microduct. The dynamic coefficient of friction for a finished cable against HDPE duct is commonly targeted at 0.20 to 0.35 when measured by a sled test adapted from ISO 8295; published data for this specific compound is limited, so the value is measured on the finished cable rather than on compression-moulded plaques. The terminal product is an air-blown fibre cable with a black HDPE outer jacket of 0.7 mm to 1.2 mm thickness, installed in continuous distances of 1,000 m to 2,000 m through microduct.