Arkema Rilsan BESNO P40 TL PA11 is a plasticised polyamide 11 resin supplied as cylindrical pellets for extrusion and injection moulding. The base polymer is synthesised from 11-aminoundecanoic acid derived from castor oil, giving the PA11 family a bio-based carbon content typically above 90% when measured to ASTM D6866. The P40 suffix corresponds to the plasticiser level, and the TL suffix indicates thermal and light stabilisation; the complete additive package is proprietary. The grade is positioned between unplasticised PA11 extrusion materials and softer high-plasticiser PA11 materials for flexible tubing, hose liners, and protective conduit.

Specification data are reported against ISO 1183-1:2019, ISO 11357-3:2018, and ISO 527-1:2019. Typical dry-as-moulded values include density 1.04 g/cm³, melting temperature 188°C, tensile modulus 1,050 MPa, and elongation at break greater than 200%. Melt volume-flow rate is controlled for extrusion, but published data for this specific configuration is limited; the current supplier datasheet should be consulted for lot-specific release criteria. Conditioned specimens at 50% RH exhibit reduced modulus and increased elongation because absorbed water acts as an additional amide-group plasticiser.

Why does the P40 plasticiser package lower modulus while retaining chemical resistance?

The P40 incorporation reduces intermolecular hydrogen bonding along the amide sequences, and the resulting modulus suppression is not uniform across temperature. Dry-state tensile modulus is lower than that of unplasticised PA11 by approximately 20–30%, while the linear aliphatic backbone retains resistance to aliphatic hydrocarbons, zinc chloride solutions, and dilute saline environments. Plasticisation also shifts the ductile-to-brittle transition to lower temperatures. In notched Charpy tests at -40°C to ISO 179-1/1eA, the grade generally shows less impact-strength loss than unmodified PA11; published data for this exact formulation is limited to supplier technical documentation, and end users should validate on production samples.

In dynamic mechanical analysis, the plasticiser broadens the glass transition region and lowers the storage modulus inflection relative to dry unplasticised PA11. At processing temperatures, the same mechanism reduces high-shear viscosity, which lowers backpressure on a 30:1 L/D single-screw extruder. The viscosity reduction is shear-rate dependent and is more evident at low shear. This changes the balance between pressure flow and drag flow in annular dies and can narrow the stable draw-ratio window during free-surface extrusion.

On a production-scale single-screw line with a 60 mm screw and 30:1 L/D barrel, barrel pressures of 120–180 bar are observed at screw speeds of 40–60 min⁻¹; shear heating elevates melt temperature by 5–10°C above the set barrel temperature. Melt temperature is measured at the die entry with an immersion thermocouple, not inferred from barrel setpoints. The plasticised melt can exhibit increased die swell relative to unplasticised PA11; die land length and draw ratio must be adjusted to control final tube diameter and wall thickness.

Drying thresholds below 0.08 wt% residual moisture are mandatory, not advisory

At 50% RH, PA11 absorbs roughly 1.0–1.2 wt% moisture within 24–48 h; saturation moisture uptake is typically 1.8 wt% to ISO 62. Residual moisture above 0.08 wt% hydrolyses the amide backbone during extrusion, producing viscosity loss, surface splay, bubbles, and reduced burst pressure in finished tube. The material is dried in a desiccant dryer with inlet air dew point ≤ -30°C and air temperature 80°C for 4–6 h. Residual water is verified by ISO 15512:2019 or equivalent Karl Fischer coulometry on a side-stream sample; gravimetric loss on drying alone is not a reliable release criterion for production lots.

Barrel profiles for a 60 mm extruder are typically set to 200°C rear, 220°C feed, 235°C compression, 240°C metering, and 225°C die. Melt temperature must remain below 260°C; residence time at temperature is kept below 10 min. These limits are not arbitrary; exceeding them accelerates thermo-oxidative chain scission despite the TL stabilisation package. Screw configurations with compression ratios of 2.8:1–3.2:1 and screen packs of 60/80/100 mesh are generally used for consistent melt quality.

Batch-to-batch variance in plasticiser content can shift melt viscosity by 5–10% on inline rheometers. On high-speed tube lines, a viscosity shift of 5% is sufficient to move tube wall thickness outside tolerance because pressure transfer along the screw changes even when barrel setpoints remain fixed. Closed-loop diameter gauges with ultrasonic wall measurement are used on modern extrusion lines to compensate for such drift without manual weight-per-metre checks.

When monolayer tubing is extruded, die swell and draw ratio define the operating envelope

The die gap is set to control draw-down ratio below 2.5:1; excessive draw-down raises frozen-in orientation and reduces burst strength. Vacuum sizing is used to hold outside diameter tolerances of ±0.05 mm on air-brake tubing with outside diameters of 6.35 mm or 9.53 mm. Cooling water temperature is held between 15°C and 25°C; lower water temperatures increase crystallinity gradients across the wall and can produce residual stress at the inner wall. Post-extrusion annealing at 120°C for 30–60 min is sometimes used for fittings or formed parts, but is not standard for continuous tube lines.

During coextrusion of PA11 tube over aramid or steel braid, the melt must be kept below 250°C to prevent thermal degradation of adhesion-promoting tie layers. Coextrusion feedblock and die temperatures are maintained within ±5°C; wider deviations produce layer-thickness variation and intermittent pinhole defects. The annular die is generally fitted with a spiral mandrel or crosshead design; for BESNO P40 TL, head pressure of 100–150 bar is common. At melt temperatures below 200°C, the material has insufficient fluidity and can produce melt fracture at the die lip; above 250°C, plasticiser volatilisation can form deposits on downstream sizing equipment.

Automotive air-brake tubing is one of the primary production applications for Rilsan BESNO P40 TL. Tube is tested to SAE J844 for tensile strength, cold flexibility, zinc chloride resistance, and humidity cycling. The P40 plasticiser package permits coiling and installation at temperatures below -40°C without visible crack formation; impact strength is verified on notched specimens to ISO 179-1/1eA. Zinc chloride resistance is relevant because road de-icing salts concentrate in chassis areas and attack unprotected polyamide grades. Proof and burst pressure verification on finished tube is commonly conducted to ISO 1402 with minimum burst pressure factors defined by the vehicle manufacturer specification.

Injection moulding is also possible for fittings, clips, and connectors. A melt temperature of 240–260°C and mould temperature of 60–90°C are typical. High injection velocity and short holding time reduce crystallinity gradients; ejection below 60°C can produce sink marks because the plasticised grade has lower modulus during cooling. The material must be dried before moulding; the same <0.08 wt% moisture limit applies to avoid nozzle drool, foaming, and reduced weld-line strength.

Comparative property data across PA11 and PA12 resin families

The table below compares supplier-published typical values for Rilsan BESNO P40 TL with unplasticised PA11 and plasticised PA12. These are not specification limits; they represent dry-as-moulded data used for preliminary screening. End users should obtain the current datasheet and validate on production equipment because reabsorbed moisture, additives, and processing history alter the final stress-strain response.

Compared with unplasticised PA11, the P40 grade lowers tensile modulus and increases low-temperature ductility. Compared with plasticised PA12, Rilsan BESNO P40 TL has a higher density and melting point, and slightly higher water absorption at saturation; PA12 is often chosen when lower weight or lower equilibrium moisture uptake is critical. Compared with PA6 or PA66 flexible grades, the PA11 backbone provides lower moisture uptake and better dimensional stability in humid service, but at higher material cost per kilogram. Within the Rilsan PA11 portfolio, a lower plasticiser content yields higher tensile modulus and better creep resistance but reduced elongation at low temperature; a higher plasticiser content lowers Shore D hardness and modulus but may increase extractables and reduce burst pressure. The P40 level is typically selected where the tube must survive repeated flexural cycling at -40°C without loss of pressure integrity while retaining sufficient hoop strength for pressurised air-brake circuits.

If the melt temperature exceeds 260°C, oxidative chain scission accelerates despite the TL stabiliser package

The TL stabilisation package delays yellowing and surface embrittlement during processing, but it does not eliminate thermal degradation. At melt temperatures above 260°C, aliphatic chain scission generates aldehydes and carbon monoxide; discolouration changes are preceded by reduced melt viscosity and reduced burst pressure in finished tubing. Visible yellowing alone is not a reliable quality criterion because stabilisers can mask colour change without preventing molecular-weight loss. Melt temperature drift above 260°C is controlled by reducing screw speed, increasing barrel cooling, or switching to a lower-compression screw.

Incompatibilities include concentrated hydrochloric acid, strong oxidising agents such as hydrogen peroxide at elevated concentration, and certain phenolic solvent systems. Continuous exposure to methanol at temperatures above 50°C may induce environmental stress cracking in restrained tube installations. The grade is not recommended for continuous service in hot water above 80°C because hydrolysis of the amide backbone accelerates with temperature; short-term excursions are acceptable only with component-level validation.

After extrusion, PA11 absorbs atmospheric moisture over 48–72 h; this conditioning increases impact strength and reduces modulus. Dimensional change during moisture conditioning is approximately 0.3–0.5% in part dimensions; high-tolerance components are annealed and conditioned before final inspection. Natural or off-white pellets may show slight yellowing after high-temperature processing, but tight control of melt temperature and residence time minimises colour drift in unpigmented extrusions.

Regulatory compliance status is not universal across all production lots. The grade may be suitable for food-contact articles under FDA 21 CFR 177.1500 and European EU 10/2011, but migration testing must be performed on the finished article. REACH and RoHS declarations are provided by Arkema through the commercial supply chain; end users should specify application-specific compliance in the purchase specification and request batch-specific certificates. The resin is not supplied with a medical-grade certification as a standard item; ISO 10993 assessment is not implied by the base material.