AXELERON MDPE DHDA-8864 BK is a fully compounded black medium-density polyethylene cable jacketing compound supplied as pellets for single-component sheath extrusion. The product is specified in telecom and coaxial cable constructions where the sheath must provide long-term environmental stress crack resistance, controlled shrinkback, low moisture vapour transmission, and carbon black dispersion sufficient for outdoor UV exposure. The following downstream profiles are restricted to established industrial cable families in which this grade is used or specified as a direct substitute for legacy MDPE jacket compounds. Each profile records the applicable compliance framework, formulation addition ratio, downstream production process, and terminal finished product classification, with operating limits derived from production-scale jacketing line behaviour and public standards documentation.

Outdoor Loose-Tube Fibre Optic Outer Sheathing Under IEC 60794-1-2 Mechanical Loading

In outdoor loose-tube fibre optic cable constructions, DHDA-8864 BK is applied as the outer sheath over a water-blocked core containing 12–288 gel-filled or dry buffer tubes. The material is specified at an addition ratio of 100 parts by weight as supplied, because the compound already contains the carbon black additive package evaluated to ASTM D1603 and the dispersion is inspected according to IEC 60811-501; no additional carbon black masterbatch is used in this configuration. Producers reintroducing clean post-industrial regrind of the same grade typically limit addition to 10–20 parts by weight of the total jacket layer, with regrind moisture held below 0.02% by weight through hot-air hopper drying at 70–80 °C for 3–4 h when ambient relative humidity exceeds 60%. Processing is performed on a 90 mm single-screw extruder with L/D 25:1, barrel zone temperatures set from 180 °C at the feed throat to 220 °C at the metering zone, screen pack 80/120/80 mesh, and crosshead die head pressure between 120 bar and 180 bar. The melt exits the tube-on crosshead at 210–230 °C and enters a segmented water trough with the first stage held at 50–60 °C to moderate quench stress; vacuum sizing is used to hold sheath concentricity within ±0.1 mm. Melt temperatures above 240 °C are not used because prolonged high-temperature residence reduces environmental stress crack resistance in the finished jacket. Terminal product types include stranded loose-tube outdoor fibre optic cables for duct, direct-burial, and aerial lashed deployment, typically with fibre counts from 12 to 288, jacket thickness between 1.0 mm and 1.5 mm, and outer sheath compliance verified against IEC 60794-1-2 mechanical tests, Telcordia GR-20-CORE Issue 4, RoHS 2011/65/EU, and REACH (EC) No 1907/2006.

In thin-wall central-tube optical fibre drop cable jacketing, the compound is extruded as an outer layer over a single gel-filled or dry-core tube containing 1–12 optical fibres. The addition ratio remains 100 parts by weight of DHDA-8864 BK as supplied for wall thicknesses of 0.4–0.8 mm; regrind is generally not introduced in walls below 1.0 mm because surface roughness and point-to-point thickness variation become critical for field termination and closure sealing. Where wall thickness exceeds 1.0 mm, clean same-grade regrind is limited to 10–15 parts by weight and is monitored by melt flow rate change relative to ISO 1133-1:2022 to detect shear-history degradation before extrusion. Production equipment is typically a 65 mm single-screw extruder with L/D 24:1, screw speed 25–45 rpm, and a pressure-controlled crosshead at 100–140 bar. Melt temperature is held at 200–215 °C, lower than for loose-tube sheathing, to limit draw-down orientation and to prevent high-speed melt fracture in thin annular sections. The extruded drop cable passes through a two-stage trough: the first stage at 40–50 °C relaxes quench strain, and the second stage at 20–25 °C sets final jacket dimensions before online diameter and eccentricity measurement. The terminal product class includes flat or round FTTH drop cables for aerial, duct, and direct-burial access networks, specified to Telcordia GR-20-CORE Issue 4 and IEC 60794-1-2, with additional verification under IEC 60811-501 for tensile properties of the sheath and RoHS 2011/65/EU for restricted substance compliance.

What Limits Direct-Buried Copper Cable Jacket Ageing in Moist Sulphate Soils?

For filled direct-buried copper telecommunication cables, the outer jacket of DHDA-8864 BK is extruded over a petrolatum-filled core and corrugated metallic armour. The material is fed at 100 parts by weight as supplied, with no dilution into a base resin because the jacket compound is fully formulated for outdoor buried service. Reintroduction of clean post-industrial regrind is capped at 20 parts by weight, and processors verify that the carbon black content of blended jacket material remains above the minimum specified in ASTM D1603 before full production runs; incompatible halogenated flame-retardant masterbatches are excluded because their carrier resins and metal oxide synergists can depress environmental stress crack resistance and create interface defects at the armour overlap. The extrusion line uses a 120 mm single-screw extruder with L/D 30:1, breaker plate screens at 80/100 mesh, melt temperature 220–240 °C, and crosshead die pressure 150–200 bar. A preheating stage raises the core surface to 45–55 °C before it enters the crosshead, reducing thermal shock at the polymer-metal interface. The jacket is cooled in a three-zone water trough with the first zone at 55–70 °C to avoid high-molecular-weight stress relaxation defects, followed by ambient water and air wipe before cable marking. Finished products are multi-pair filled buried copper subscriber cables, typically from 50 to 3600 pairs, used in rural distribution and direct-burial local loops. Compliance includes ANSI/ICEA S-84-608-2002 for filled telephone cable, Telcordia GR-421-CORE for loop cable jackets, RoHS 2011/65/EU, and REACH (EC) No 1907/2006. Field failure modes observed when jacket regrind is not dried include random pinholes at the metallic armour overlap and increased ESCR failure under ASTM D1693 Condition C due to moisture-volatilised surface defects.

Coaxial trunk and distribution cable jacketing in coastal aerial installations uses DHDA-8864 BK as the outer sheath over a bonded aluminium or copper outer conductor. The material is applied at 100 parts by weight as supplied, without colour concentrate, because the black compound provides a uniform surface for outdoor ageing tests and arc resistance checks. Regrind from the same coaxial jacket line is permitted at 10–20 parts by weight when the resulting sheath passes online spark testing at 3 kV and dimensional checks at ±0.05 mm on the finished diameter. Extrusion is carried out on a 75 mm single-screw extruder with L/D 25:1, screen pack 80/100 mesh, melt temperature 215–225 °C, and crosshead die pressure 130–160 bar. The core is preheated to 40–50 °C, and the jacketed cable is quenched in a two-stage trough with a 50–55 °C first zone to reduce shrinkback at cable support attachments and pole hardware. Terminal product types include 75 Ω aerial trunk and distribution coaxial cables used in hybrid fibre-coaxial access plants, with jacket diameters typically between 6 mm and 10 mm. Applicable standards are IEC 60096-0-1 for radio-frequency cable design guidance, EN 50117-4 for distribution coaxial cable, RoHS 2011/65/EU, and REACH (EC) No 1907/2006. Where coastal ozone and salt fog exposure is specified, the black MDPE surface is assessed under ISO 4892-2 accelerated weathering criteria established by the cable purchaser.

When Fibre-to-the-Tower Hybrid Cables Require a Moisture Barrier Without Halogenated Jackets

Hybrid fibre/copper trunk cables used between baseband units and remote radio heads are sometimes specified with non-halogenated polyethylene jackets to avoid acidic gas release during aerial fires; DHDA-8864 BK is used as a moisture-barrier outer sheath in such constructions where the pathway is outdoor or tunnel-grade but not riser-rated. The formulation addition ratio is 100 parts by weight of the compound as supplied, with no halogenated synergist or flame-retardant addition because the material is not designed for riser-rated indoor paths. Clean same-grade regrind is restricted to 10–15 parts by weight, and its melt flow rate is compared against ASTM D1238 at 190 °C and 2.16 kg to detect shear-history degradation before the compound is returned to the feed hopper. Processing on a 90 mm single-screw extruder with L/D 30:1 uses a barrier screw with screw speed 35–55 rpm, melt temperature 220–235 °C, and crosshead pressure 140–190 bar. A hot-air core preheater at 50–60 °C is used before the die to minimise interfacial stress around corrugated steel armour and to prevent localised sheath debonding during cold bending. The terminal products are outdoor hybrid trunk cables carrying 12–48 optical fibres and 2–8 copper conductors for DC power or control, with outer sheath wall thickness between 1.0 mm and 1.4 mm. Compliance references IEC 60794-1-2, Telcordia GR-20-CORE Issue 4, and RoHS 2011/65/EU. Published data for this specific hybrid configuration is limited; processors are advised to validate moisture vapour transmission and sheath shrinkage on the completed hybrid design rather than transferring test values from single-material fibre optic cable constructions.

Reducing Shrinkback in Slotted Core Optical Fibre Cable Jacketing

Slotted core optical fibre cable constructions require an outer jacket that remains dimensionally stable after repeated diurnal temperature cycles, because the slotted core is not gel-filled and contains exposed fibre ribbons in open slots. DHDA-8864 BK is extruded over the slotted core at 100 parts by weight as supplied, with no filler masterbatch; regrind is introduced at 10–20 parts by weight only when post-extrusion shrinkback measurements on the first production length meet the IEC 60794-1-2 jacket shrinkback criterion established by the cable manufacturer. The jacketing line uses a 120 mm single-screw extruder with L/D 25:1, melt temperature 210–230 °C, die head pressure 150–200 bar, and a screw speed of 30–50 rpm. A long hot-water quench at 55–65 °C in the first trough section is maintained to stabilise crystalline orientation before final cooling to 20–25 °C; this thermal sequence reduces post-extrusion longitudinal shrinkage that would otherwise expose the open ribbon slots at cable terminations. The terminal finished goods are slotted core cables for long-haul and metropolitan networks, commonly with 144–432 fibres in ribbon stacks, jacket diameter from 8 mm to 12 mm, and wall thickness from 1.0 mm to 1.4 mm. The relevant compliance framework includes IEC 60794-1-2, Telcordia GR-20-CORE Issue 4, IEC 60811-501 for sheath mechanical properties, ASTM D1693 Condition C for environmental stress crack resistance, and RoHS 2011/65/EU for restricted substance verification.