Grilamid L 16 W 20 black 9995 is a flexible polyamide 12 extrusion grade supplied by EMS-Grivory. The product is classified as PA12 according to ISO 1043-1 and is positioned within the manufacturer’s Grilamid L range for melt-extrudable components. The L 16 segment identifies the base melt viscosity class; W 20 identifies a plasticizer modification that reduces hardness and tensile modulus; black 9995 denotes a carbon black pigmentation package that provides opacity and ultraviolet screening in thin-walled profiles. In the conditioned state, test specimens are equilibrated at 23 °C and 50 % relative humidity to mass constancy according to ISO 291, or conditioned by accelerated moisture uptake according to ISO 1110 for comparative data. Conditioning is not a cosmetic laboratory step for PA12: absorbed water occupies amide sites, reduces tensile modulus, increases ductility, and alters dimensional response. Because PA12 has a lower amide-group density than PA6 or PA66, its conditioned moisture uptake is comparatively low, but the plasticizer phase adds a second non-polar domain that affects moisture diffusion and surface equilibration.

Within thin-wall flexible tubing and conduit applications, the material is normally specified when room-temperature flexibility is required without blending a separate elastomer. The W 20 plasticization lowers Shore D hardness and tensile modulus while retaining the PA12 backbone. Product data sheets from comparable plasticized PA12 grades report dry tensile modulus in the range of 300–450 MPa and conditioned modulus in the range of 200–300 MPa when tested according to ISO 527-1/-2. Conditioned notched Charpy impact specimens tested under ISO 179-1/1eA frequently show no break at 23 °C, while dry specimens may give lower absorbed-energy values because the notch-tip plastic zone is less developed. These differences are important when incoming quality control is performed on dry-as-moulded test bars and then used to evaluate wet-service components.

For dimensional control, conditioning causes a measurable linear expansion relative to the dry-moulded state. The equilibrium moisture content for the PA12 backbone is typically 0.80–1.10 % at 23 °C / 50 % RH and 1.2–1.5 % at saturation according to ISO 62. The corresponding hygroscopic expansion coefficient of PA12 is low relative to PA6, but the plasticized grade should be measured on the downstream part geometry because wall orientation in the extrusion direction changes anisotropy. A conditioned part with wall thickness below 1.0 mm reaches equilibrium faster than a thick-walled structural block; ISO 291 equilibrium timetables should be adjusted using mass-change plots rather than fixed duration.

Plasticizer Loading and the Shift in Low-Temperature Ductility

The W 20 modification is a plasticizer-loaded PA12 system, not an impact-copolymer alloy. The plasticizer reduces intermolecular hydrogen bonding between amide segments by increasing free volume, which lowers the glass transition region and extends the ductile plateau into subzero conditions. The practical result is improved retention of flexibility at -40 °C; comparable plasticized PA12 grades often retain notched impact values above 10 kJ/m² at this temperature, though the black 9995 formulation should be confirmed against the current EMS-Grivory datasheet. Creep and stress-relaxation behaviour are more time-dependent than in unplasticized PA12, so the short-term tensile modulus is not sufficient for load-bearing calculations. Isochronous stress-strain data or creep modulus at 1000 h and 23 °C should be requested when the part is under constant clamping force or internal pressure.

Because plasticizer addition reduces modulus, the heat deflection temperature under ISO 75-2 method B falls below that of unplasticized PA12. The grade is therefore not a direct substitution for glass-filled or mineral-filled PA12 in brackets and housings. It is more appropriate for cylindrical profiles, corrugated conduits, and pneumatic lines where bending compliance and kink resistance are the primary mechanical requirements. The lower crystallinity associated with plasticizer loading also reduces the sharp dimensional change at the PA12 melting point, but it broadens the softening range; extrusion calibration tanks must therefore account for reduced melt stiffness during quench.

What Are the Practical Melt-Tooling Limits for Black 9995 Pigmented Tubing?

The grade should be pre-dried in a desiccant-bed dryer at 80 °C for 4–8 h to a residual moisture level below 0.10 % measured by ISO 15512. The drying-air dew point should not rise above -30 °C. Moisture above this threshold hydrolyses the PA12 backbone during melt processing and produces surface splay, diameter surging, and loss of melt strength. Melt temperature at the die entry should be kept between 210 °C and 250 °C; the short-term upper limit at the die exit is 260 °C because plasticizer vapour pressure rises sharply beyond this boundary. Screws with L/D ratios from 24:1 to 30:1 and compression ratios around 3:1 are suitable for consistent feed of black 9995 concentrate. Melt pumps are strongly recommended for thin-wall tube extrusion to decouple die pressure from extruder screw speed and to reduce pulse-induced wall thickness variation.

For corrugated conduit lines with grooved caterpillar haul-offs, the practical problem is not only melt temperature but also melt strength. The L 16 base viscosity is sufficient to fill corrugator moulds at high line speed, yet the material remains soft at the sizing block. If die head pressure exceeds 100 bar at normal throughput, the melt temperature should be checked before raising screw speed; viscous dissipation may push the melt beyond the plasticizer limit even when barrel setpoints remain within the nominal range. In such cases, reducing screw speed and increasing barrel temperature in the metering zone may be less damaging than further increasing shear heating.

In multi-layer coextrusion with a polyolefin core, the black 9995 outer layer should not fall below 0.15 mm unless the carbon black dispersion is certified for the planned draw-down ratio. Dispersion quality is assessed by microscopic rating per ISO 11420. Poor dispersion produces visible agglomerates and can initiate pinholes in thin-wall tube; this failure is not detected by standard density or melt-flow testing.

When Continuous Service Above 80 °C Encounters Plasticizer Migration Limits

Continuous service above 80 °C is the critical design boundary for this grade in open-air applications. Plasticizer migration to the surface intensifies with temperature and airflow, producing surface haze, gloss loss, and progressive loss of flexibility. For under-hood tube bundles or engine-compartment cable conduits, the local clip-point air temperature should be measured rather than assumed from general vehicle-bay data. If the measured temperature exceeds 80 °C, the manufacturer should be asked for plasticizer volatility data based on ISO 11358 thermogravimetric analysis and heat-ageing according to ISO 15799. Published data for this specific configuration is limited; generic PA12 plasticizer-loss rates cannot be directly substituted for the black 9995 formulation.

Chemical contact with strong acids, chlorinated solvents, or alcohols at elevated temperature can also extract the plasticizer. In fuel-contact components, the applicable test is usually ISO 13775-1 or an OEM-specific fuel immersion protocol; this plasticized grade should not be selected for immersed fuel-sender components unless the plasticizer extraction curve is known and approved. For pneumatic and cable-protection applications exposed to diesel spray, hydraulic oil mist, and road salt, the PA12 backbone provides resistance, but the plasticizer can alter swelling and weight change relative to unplasticized PA12. Long-term exposure validation should include mass-change measurements after 1000 h in the service fluid at the upper operating temperature.

Compared with unplasticized Grilamid L 16, the W 20 grade gives lower Shore D hardness, lower tensile modulus, higher room-temperature elongation, and improved low-temperature ductility. The trade-off is lower heat deflection temperature and higher creep under load. Compared with PA11, the PA12 backbone offers lower equilibrium moisture uptake and generally higher melting point, but plasticizer choice dominates low-temperature flexibility. Compared with PA6 or PA66, the PA12 structure reduces moisture sensitivity and improves dimensional stability in humid service, but absolute tensile strength and modulus are lower. The following table summarizes the principal comparative differences with the relevant test standards.

Regulatory classification must be confirmed for the end-use jurisdiction. The grade is an industrial resin; REACH Article 33 screening and RoHS Directive 2011/65/EU Annex II compliance depend on the stabilised and pigmented formulation. Food-contact status under FDA 21 CFR 177.1500 or EU 10/2011 is not automatic for the black 9995 colour code and must be verified against the current supplier statement. The same applies to drinking-water approvals such as NSF/ANSI 61 or DVGW W270, which are grade-specific and cannot be assumed from the base PA12 alone.

Melt viscosity measured by capillary rheometry at 230 °C in a dry state should show shear-thinning consistent with extrusion-grade PA12. At apparent shear rates from 100 s⁻¹ to 1000 s⁻¹, the flow curve is used to size the breaker plate and land-length ratio; if the plasticizer lowers melt viscosity, the extruder head pressure may be lower than unplasticized PA12 by 20–40 %. This means screw speed and melt pump setpoints cannot be transferred from unmodified PA12 processes without adjusting the throughput model. Pressure transducers should be installed at the breaker plate and die inlet to monitor filtration and gel accumulation.

The most common production failure mode is not polymer degradation but plasticizer condensation in the calibration tank. When the hot tube enters water at 40 °C, volatile plasticizer traces can deposit on sizing rings, increasing drag and producing outside-diameter scratches. For this reason, the vacuum calibration tank should have a surface skimmer or continuous water overflow. The second common failure is over-drying at too high a temperature; oven drying above 100 °C can drive off low-molecular-weight plasticizer fractions and produce a harder, less flexible part. The resulting material may still pass density tests but fail Shore D and low-temperature impact requirements.

On cable sheathing and pneumatic tube lines, the conditioned flexibility permits tighter routing than unplasticized PA12, but bend radii and tube ovality must be validated on the formed part. The carbon black package in black 9995 provides ultraviolet screening for outdoor use, but surface chalking and gloss retention are partly thickness-dependent. For outdoor conduit exposed to continuous high humidity, the conditioning moisture uptake reduces hardness further; therefore, mechanical acceptance testing should be performed after conditioning to ISO 291, not on dry-as-received pipe.

Batch-to-batch variation in plasticizer level can appear as Shore D shifts of ±2–3 points and tensile modulus changes of ±50 MPa. Incoming extrusion operations should therefore record the supplier lot number, pre-drying residual moisture, and melt temperature for each run. If a Shore D sample tested under ISO 868 falls outside the agreed range after conditioning, the full mechanical property set should be rechecked before changing tooling; moisture conditioning history and specimen preparation are more common sources of error than resin composition drift.