Arkema Rilsan BESN BLACK P40 TL01 is an unfilled polyamide 11 extrusion grade supplied as black pellets. The base polymer is synthesised from 11-aminoundecanoic acid, a monomer derived from castor oil, producing a polyamide backbone with one amide group per 11 methylene units. This structure yields a crystalline melting temperature near 189 °C when measured by ISO 11357-3 and a density of approximately 1.04 g/cm³ under ISO 1183-1. The BESN designation identifies the standard-viscosity extrusion series within the Rilsan PA11 portfolio. The BLACK P40 TL01 suffix denotes a carbon-black-containing formulation with a proprietary stabilisation and processing package; the exact additive composition is not disclosed on the technical data sheet, so published data for this specific configuration is limited to release-relevant physical and processing properties.

Typical dry-as-moulded tensile modulus for the BESN series ranges from 1000 MPa to 1300 MPa when tested to ISO 527-2, with tensile yield stress commonly between 30 MPa and 40 MPa. Nominal strain at break is controlled above 50 % in thin extruded sections, although orientation and wall thickness influence the measured value. After conditioning at 23 °C and 50 % relative humidity, PA11 absorbs approximately 1.1 % moisture, which reduces tensile modulus and increases elongation relative to dry-as-moulded values. Saturation in water at 23 °C reaches approximately 1.8 % to 2.0 % by ISO 62. These figures are typical lot averages rather than absolute specification limits; batch-specific values are recorded on Arkema certificates of analysis.

What Limits Dimensional Stability in Humid Service Environments?

The lower amide-group concentration in PA11 compared with PA6 and PA66 restricts equilibrium water uptake. Table 1 summarises typical moisture absorption and thermal properties across polyamide families under ISO 62, ISO 11357-3, and ISO 1183-1. The practical consequence is reduced hygroscopic growth in PA11 extruded tube walls. A 1 % moisture increase in PA6 can produce linear expansion of roughly 0.25 % to 0.35 %, whereas PA11 typically remains below 0.15 % at the same conditioning step. These are material-class properties rather than grade-specific values for BESN BLACK P40 TL01, but they govern dimensional tolerance selection in humid or wet compartments where PA6 and PA66 would require wider design allowances.

The carbon black used in BLACK P40 TL01 does not materially alter equilibrium moisture uptake compared with natural BESNO P40 TL, because the black is not a hydrophilic filler at commercial loadings. However, black pigmentation changes the thermal response of the pellet and extrudate under infrared reheating. In production trials on tube calibration lines, black PA11 reaches target surface temperature faster than natural PA11 at the same infrared emitter output. Medium-wave infrared heater intensity is therefore reduced by 10 % to 20 % to avoid surface oxidation before sizing. This adjustment is equipment-specific and is normally established by thermocouple profiling of the extrudate surface, not by a global standard.

Pre-Drying, Melt Temperature, and Screw Geometry

Residual pellet moisture must be reduced below 0.15 % before extrusion because water hydrolyses the amide bond at processing temperature, lowering melt viscosity and producing splay, bubbles, and poor surface finish. Desiccant drying at 80 °C to 90 °C for 4 to 6 h is the standard start-up condition, with process-air dew point below −30 °C. In plants where ambient relative humidity exceeds 60 %, open hopper residence time is limited, and sealed hoppers with nitrogen purge are preferred to prevent moisture regain.

Single-screw extrusion of BESN BLACK P40 TL01 is carried out on screws with an L/D ratio of 24:1 to 30:1, compression ratio 2.5:1 to 3.5:1, and barrier or Maddock mixing sections to disperse carbon black. Rear-to-die barrel set points are commonly 220 °C, 240 °C, 245 °C, and 250 °C, with melt temperature measured by immersion probe maintained between 230 °C and 260 °C. Residence time above 10 min or melt temperature above 280 °C initiates chain scission and produces black specks in the extrudate. Melt volume-flow rate of the BESN series typically falls between 5 cm³/10 min and 15 cm³/10 min at 235 °C and 2.16 kg under ISO 1133-1, which positions the material for tube and profile extrusion rather than thin-wall injection moulding without flow-length verification.

Tube dies require die land-length ratios above 10:1 to stabilise melt fracture and control draw-down. Screen packs from 40 mesh to 80 mesh remove carbon-black agglomerates. A rising filter pressure above the line-specific baseline indicates poor dispersion and is corrected by increasing mixing-section temperature by approximately 5 °C rather than by increasing screw speed, because higher shear heating can degrade the polymer. On vented extruders, vacuum below −0.08 MPa is applied after the melt seal to strip residual moisture and volatile degradation products.

In automotive air-brake tube production governed by SAE J844, the grade is processed as a monolayer tube or as the inner layer of a coextruded structure. Low-temperature impact response is measured by ISO 179-2 Charpy method at −40 °C; PA11 homopolymer typically retains notched impact energy above 5 kJ/m² under dry-as-moulded conditions, whereas many PA6 grades fall below 4 kJ/m² at the same temperature. For fuel filler and vapour lines, the final assembly rather than the polymer alone is validated to SAE J2260; the tube construction, connectors, and end fittings are qualified as a system.

Polyamide 11 grades are also used as pressure sheaths in unbonded flexible risers qualified under API Spec 17J. BESN BLACK P40 TL01 can be considered where a black carbon-filled PA11 is required for ultraviolet protection, but re-qualification by the pipe manufacturer is mandatory for methanol exposure, sour gas resistance, and ageing at design temperature. Published data for this specific configuration is limited; the qualification reports are proprietary to project owners and pipe suppliers.

When PA11 Replaces PA12 in Coextruded Tubing

PA12 is frequently used as the benchmark for low-moisture extrusion tubing. BESN BLACK P40 TL01 differs from typical plasticised PA12 in melting point, density, and renewable-carbon content. Its melting point of 189 °C is 10 °C to 12 °C above ordinary PA12 at 178 °C, so downstream infrared reheating and forming stations require either higher emitter settings or longer dwell. Density is 1.04 g/cm³ against 1.01 g/cm³ for PA12, producing an approximate 3 % mass increase per metre of tube at identical wall thickness. Tensile modulus of dry PA11 can be comparable to plasticised PA12, but the PA11 backbone may show higher elastic recovery in spiral and convoluted tube geometries.

Compared with glass-filled or mineral-filled polyamides, the unfilled BESN BLACK P40 TL01 creates lower tooling abrasion during coextrusion. It does not, however, provide the flexural stiffness of 30 % glass-fibre PA66, which can exceed 7000 MPa under ISO 178; the unfilled grade remains near 900 MPa to 1200 MPa. This limits its use in structural brackets, load-bearing under-hood components, or applications where creep under continuous load is controlled by fibre reinforcement. For fluid transport, cable sheathing, and extruded profiles exposed to hydrocarbons and cold impact, the unfilled PA11 matrix provides the relevant property balance.

Inside the Rilsan PA11 range, BESN BLACK P40 TL01 is the black carbon-pigmented variant of the BESN extrusion series. It is not a high-flex plasticised product such as BESV P20. The P40 suffix indicates the specific formulation variant, but the exact plasticiser content is proprietary. Substituting from BESNO P40 TL natural to BLACK P40 TL01 requires re-evaluation of ultraviolet exposure, weld-line appearance, and colour-dependent laser marking; tensile and flexural properties generally remain within normal lot-to-lot variation. The replacement of a natural PA11 with a black PA11 may also change melt surface temperature under the same infrared heater settings, so process adjustments should be recorded against final wall-thickness data.

Immersion screening according to ISO 175 indicates that PA11 absorbs aliphatic and aromatic hydrocarbons more slowly than PA6 because of its lower amide density. Polar solvents such as methanol and strong acids, however, attack the polyamide chain. The material is not rated for continuous immersion in concentrated acetic acid or hydrochloric acid at temperatures above 40 °C. Brake fluid resistance is specific to glycol-ether formulations; prolonged exposure to DOT 3 or DOT 4 fluids above 80 °C can plasticise the surface and reduce burst pressure in thin-walled tube, so system-level validation remains mandatory.

The grade is supplied with REACH and RoHS Directive 2011/65/EU declarations covering lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE below the directive’s maximum concentration values; compliance is confirmed on the lot certificate. No statement is made here concerning food-contact suitability for this black formulation. Food-contact PA11 grades are controlled separately under FDA 21 CFR 177.1500 or European Union Regulation 10/2011. Users requiring potable-water or medical-grade documentation must confirm the specific grade approval with Arkema, because the carbon-black and stabilisation package in BESN BLACK P40 TL01 may not be covered by those clearances.