EMS-Grivory Grilamid® L 20A HL NZ nat is a natural-coloured, heat-stabilised polyamide 12 compound based on a medium-viscosity base resin. The grade is supplied as cylindrical granules and is intended for injection moulding and extrusion processes requiring lower moisture uptake, lower density, and resistance to aliphatic hydrocarbon environments. Under ISO 1183-1, the dry density is approximately 1,010 kg/m³; under ISO 62, saturation water uptake in 23 °C water is about 1.4% by mass, compared with 8–10% for unreinforced PA6 and 7–9% for unreinforced PA66 under the same standard. The suffix HL denotes heat- and light-stabilised material; NZ is an internal grade modifier used by EMS; nat indicates natural colour without added pigment. The L 20A viscosity designation places the product between low-viscosity connector grades and high-viscosity pipe grades, making it suitable for thin-wall technical components and small-diameter tubing. Because the product is not an externally plasticised PA12, low-temperature flexibility below -40 °C should be verified against plasticised PA12 or copolyamide alternatives.

Melt Rheology and Shear Rate Limits in Extrusion Tooling

On a 30 mm single-screw extruder with L/D 30, a three-zone screw having 2.5:1 compression ratio, and a 24/40/60 mesh screen pack, the recommended melt temperature measured at the die is 220–240 °C. The medium-viscosity PA12 melt responds strongly to shear heating; sustained screw speeds above 80 min⁻¹ can generate melt temperatures above 250 °C and deplete the HL stabilizer package. If melt pressure before the breaker plate exceeds 300 bar, the pressure-drop contribution of the screen pack should be isolated by comparing die-inlet pressure with breaker-plate pressure. A pressure drop greater than 30% of total die pressure indicates screen blockage or inadequate melt filtration and may cause weld-line splitting in multi-strand profiles. In tube extrusion, the draw-down ratio at the calibrator should remain between 1.05:1 and 1.20:1; lower values produce diameter oscillation, while higher values reduce hoop strength.

Residual moisture is the dominant source of surface splay and hydrolysis in processing. In a desiccant dryer with a dew point below -40 °C, the granulate should be dried at 80 °C for 4–8 h to reach a maximum residual moisture of 0.10% by mass. Closed hopper loading with dry-air purge is required for injected shot capacities above 500 g or production runs longer than 8 h. If granulate is exposed to 60% relative humidity for more than 30 min, re-drying is necessary because PA12 absorbs surface moisture rapidly even though its equilibrium saturation is low.

What Distinguishes L 20A HL NZ nat from Standard PA12 Pipe Grades?

For converters evaluating L 20A HL NZ nat against standard PA12 pipe grades, the primary difference is molecular weight and viscosity. Standard PA12 pipe extrusion compounds are usually higher-viscosity grades with lower melt volume-flow rates under ISO 1133-1; this supports large-diameter annular cross-sections and long calibration runs but limits thin-wall injection filling. L 20A HL NZ nat has a medium-viscosity base, so it provides shorter filling times in injection moulds with wall thickness below 1.5 mm, but lower melt strength in large-diameter profile extrusion. The dry tensile modulus determined by ISO 527-1/-2 is approximately 1,400 MPa, which is comparable to unreinforced PA12 pipe grades, while a 30% glass-fibre-reinforced PA12 typically reaches 3,000–4,000 MPa under the same standard. Notched Charpy impact strength by ISO 179-1/1eA is approximately 8 kJ/m² dry and 12 kJ/m² conditioned at 23 °C. Compared with PA11, the PA12 backbone has one amide group per 12 carbon atoms versus 11, reducing hydrogen-bond density and producing a slightly lower dry density, lower water uptake, and a melting temperature around 176 °C by ISO 11357-1/-3. Compared with PA6 and PA66, the PA12 grade has lower modulus and lower short-term heat deflection temperature, but its dimensional change from moisture uptake is smaller.

Chemical resistance is evaluated in immersion testing according to ISO 175. The PA12 matrix retains tensile strength after 500 h exposure at 60 °C to ASTM Reference Fuel C and IRM 903 oil, but stress cracking can occur when moulded components are exposed to zinc chloride solutions above 50% concentration or to strong mineral acids. For methanol-containing fuels above 15 vol%, published data for this specific grade is limited; qualification under the relevant SAE J1681 or OEM fuel system specification is required before production release. If fuel connectors are moulded with residual surface stress above 15 MPa, annealing at 70–90 °C for 4 h is commonly used to reduce stress-cracking risk. Contact with phenol, cresol, or concentrated formic acid dissolves or swells PA12 and is a processing incompatibility.

When Heat Stabilization Replaces External Antioxidant Masterbatch in Cable Jacketing

When the HL stabilization package is selected for cable sheathing, the converter can reduce or eliminate a separate copper-halide antioxidant masterbatch in dry indoor service below 100 °C conductor temperature. The stabilizer system addresses thermo-oxidative chain scission during processing and long-term ageing, but it does not provide the same copper-contact performance as a dedicated copper-stabilised PA12 cable jacket grade. Air-oven ageing under ISO 188 can be used to verify tensile strength and elongation retention; unstabilized PA12 may lose more than 50% of original elongation after 2,000 h at 120 °C, whereas stabilized PA12 systems are generally specified to retain higher values. The exact retention curve for L 20A HL NZ nat should be obtained from the supplier certificate because additive loading is not disclosed on standard product literature. In cable extrusion, the melt should be filtered through a screen pack with a maximum aperture of 125 µm to remove gel particles that can cause spark-test failures under IEC 62230.

Thermal and mechanical values are summarised for dry and conditioned states.

Thermal ageing in air at 100 °C, 120 °C, and 140 °C under ISO 188 is the standard method for generating retention curves. The property that declines first is elongation at break, not tensile strength, because chain scission reduces molecular weight and destroys tie-molecule connectivity. For unstabilized PA12, elongation at break can fall below 50% of the original value within 500–1,000 h at 120 °C; the HL designation is intended to extend this time. However, the exact ageing curve depends on specimen thickness and air changes in the oven. ISO 188 specifies a minimum air change of 3–10 changes per hour; if the laboratory uses lower air exchange, the apparent life is overestimated. Dimensional change due to moisture absorption also follows thickness-dependent kinetics. For a 2 mm thick test plaque stored at 23 °C and 50% relative humidity, the equilibrium water content is approximately 0.7% by mass. The associated linear dimensional change is typically less than 0.2%, but for precision components with tolerances below 0.10 mm, this is significant. Shrinkage after moulding according to ISO 294-4 is usually in the range 1.0–1.5% in the flow direction and 1.0–1.8% transversely, depending on gate size and holding pressure.

On injection moulding lines with clamp force below 2,000 kN, flash can occur if the projected area of the runner and cavities exceeds 600 cm², because PA12 cavity pressure at the end of fill is generally 30–45 MPa. A clamp force of at least 2,400 kN is therefore required for that projected area. Splay defects reflecting residual moisture typically appear at granulate moisture levels above 0.12% by mass. For valve-gated hot-runner systems, the valve stem should close against a flat gate seat because PA12 melt can string if the gate remains partially open during mould opening. Screw-recovery settings should use a back pressure of 5–15 bar and a screw surface speed below 0.3 m/s to avoid excessive shear heating.

Select Processing Parameters Based on Final Wall Thickness

For applications requiring electrical insulation, the PA12 base is typically classified as a dielectric with volume resistivity on the order of 10¹⁰–10¹² Ω·m under IEC 62631-3-1 after conditioning at 23 °C and 50% relative humidity. Because the material is hygroscopic, surface and volume resistivity decline when moisture content increases; test values obtained immediately after dry-as-moulded conditioning are not representative of humid service. The grade has a UL 94 classification of HB at 1.6 mm thickness according to the supplier’s yellow card unless the application requires a V-0 rating, in which case a flame-retardant PA12 or alternative polyamide system must be selected.

Regulatory compliance for this grade is lot-specific. The base polyamide 12 may be assessed under FDA 21 CFR 177.1500 or EU Regulation (EU) No 10/2011 for food-contact uses only when the supplier has provided a written food-contact declaration; the natural HL grade does not automatically carry such a listing. For automotive fluid handling, qualification is usually performed against SAE J2260 for non-metallic fuel system tubing and SAE J844 for air brake tubing, using the OEM-specific thermal cycling and stress-crack test schedule. Electrical applications require confirmation of comparative tracking index and volume resistivity under IEC 60112 and IEC 62631-3-1 respectively; these values are not fixed by the PA12 base and may shift with moisture conditioning. REACH, RoHS, and conflict-mineral declarations should be taken from the current EMS Grivory material datasheet and safety data sheet; the product may contain processing aids and stabilizer residues that affect waste-incineration or recycling classifications under local regulations.