EMS-Grivory Grilamid L 25 LM Nylon 12, Conditioned is an unreinforced, low-viscosity polyamide 12 injection-moulding grade in the Grilamid L 25 series. In this product designation, “Conditioned” refers to test specimens or moulded parts brought to moisture equilibrium in a standard atmosphere of 23 °C and 50 % relative humidity according to ISO 291, or to the accelerated polyamide conditioning procedure defined in ISO 1110. The conditioned state is not a chemical modification or stabiliser addition; it is the reversible moisture uptake that occurs when PA12 absorbs water from ambient air. Because PA12 has a lower amide-group density than short-chain polyamides such as PA6 and PA66, the equilibrium moisture content remains comparatively low. Saturation water absorption for this grade is typically reported between 1.4 % and 1.5 % by mass under ISO 62. The practical consequence of conditioning is a reduction in tensile modulus and yield stress, accompanied by an increase in notched impact strength and elongation at break relative to the dry-as-moulded state. These changes are reversible by drying, and therefore both conditioned and dry property limits must be considered during part design.

Physical property envelope after ISO 291 and ISO 1110 conditioning

Industrial datasheets for this grade position density at approximately 1.01 g/cm³ when measured to ISO 1183. Conditioned tensile modulus is generally reported in the range of 900 MPa to 1200 MPa using ISO 527-1/-2 type 1A specimens, whereas dry-as-moulded modulus is closer to 1400 MPa to 1600 MPa. Yield stress under the same tensile test falls between 35 MPa and 45 MPa after conditioning. Nominal strain at break is typically above 50 %, and in several published datasets the conditioned specimens exhibit a broad yielding plateau rather than a sharp yield point. Charpy notched impact strength at 23 °C according to ISO 179/1eA is commonly reported above 8 kJ/m², with some batches showing partial or complete no-break behaviour after conditioning. These shifts are consistent with water acting as a plasticiser in the amorphous phase of the semicrystalline polymer.

Thermal analysis by differential scanning calorimetry in accordance with ISO 11357-3 places the melting peak between 174 °C and 180 °C, which is characteristic of the polyamide 12 crystallite population. The Vicat softening temperature under ISO 306/A50 is typically reported between 140 °C and 150 °C. Heat deflection temperature under ISO 75-2/B at 0.45 MPa is generally between 115 °C and 135 °C. The coefficient of linear thermal expansion in injection-moulded plaques is anisotropic, with published values near 1.0 × 10⁻⁴ K⁻¹ to 1.3 × 10⁻⁴ K⁻¹ parallel to flow and somewhat higher perpendicular to flow. Volume resistivity under IEC 62631-3-1 is typically greater than 1 × 10¹² Ω·m, and the comparative tracking index is commonly above 600 V under IEC 60112. Electrical properties are not strongly degraded by the low equilibrium moisture content of PA12, but re-qualification is required after condensing humidity or direct water contact.

What separates this conditioned L 25 LM grade from general-purpose PA12 and short-chain polyamides?

Three material-selection differences are dominant. First, PA12 absorbs less moisture than PA6 and PA66. PA6 saturation values are commonly reported near 9 % to 10 %, and PA66 near 8 % to 8.5 %, under ISO 62. Grilamid L 25 LM remains at approximately 1.4 % to 1.5 % saturation. The result is lower dimensional change under fluctuating humidity and a narrower mechanical-property shift between dry and conditioned conditions. Second, PA12 density at approximately 1.01 g/cm³ provides mass reduction compared with PA66 at 1.13 g/cm³ to 1.15 g/cm³. Third, polyamide 12 retains ductility at low temperatures to at least −40 °C and shows good resistance to hydrocarbon fuels, oils, and many non-polar service fluids. Fuel resistance is commonly assessed by mass change and retained tensile properties after immersion in Fuel C or Fuel D using ISO 1817 or ISO 175. Compared with general-purpose PA12, the L 25 LM variant is positioned for thin-wall injection-moulded components requiring low moisture sensitivity and high flow. Direct comparison data against every L 25 sub-grade is limited, and the current supplier datasheet remains the binding qualification document.

In dry-air handling and plastication, the granulate must be dried to approximately 0.10 % residual moisture or less. Standard PA12 practice uses dry-air drying at 80 °C for 4 h to 6 h, with a dew point at or below −30 °C. Processing on a conventional injection-moulding machine with a general-purpose polyamide screw having an L/D ratio of 18:1 to 22:1 and a compression ratio of 2.2:1 to 2.8:1 is acceptable. Barrel temperature profiles from rear to nozzle are commonly set between 220 °C and 270 °C. Melt temperature measured by air-shot pyrometer is typically 240 °C to 260 °C. Mould temperature should be maintained between 30 °C and 80 °C, with lower settings favouring cycle time and higher settings improving surface reproduction and crystalline uniformity. Holding pressure must be adjusted to avoid sink marks, but excessive holding pressure above 70 MPa hydraulic specific pressure can increase moulded-in stress and reduce impact performance. Mould shrinkage parallel to flow is commonly reported between 0.7 % and 1.3 % for 2 mm plaques, with transverse shrinkage typically 0.1 to 0.3 percentage points higher.

When snap-fit and resilient fastening components require low moisture sensitivity

Conversion of automotive interior clips, cable ties, and fuel-line retainers from PA66 to polyamide 12 grades is frequently driven by the need to reduce the mechanical-property swing caused by humidity. Production-scale experience on multi-cavity cold-runner tools for snap-fit fasteners shows that mould temperature uniformity, hold-time optimisation, and post-mould conditioning have a measurable influence on engagement force retention. In small snap-fit geometries, lot-to-lot Charpy notched impact in the conditioned state remained within ±10 % when granulate moisture content was held below 0.10 %; excursions above 0.15 % produced visible splay and short-shot variation. For cable ties produced from injection-moulded strip, tensile yield is commonly evaluated using ISO 527-1/-2, while unlocking force and flexural fatigue are evaluated on product-specific fixtures; published data for this specific configuration is limited, so application validation remains mandatory.

In fluid-handling and cable-management components, conditioned PA12 is selected where low-temperature flexibility, stress-crack resistance, and dimensional stability under humidity are required. Pneumatic tubing, quick connectors, and cable conduits benefit from the material’s low density and resistance to zinc chloride solutions, engine oils, and diesel fuel. When tested under ISO 16750-3 vibration profiles or equivalent OEM specifications, retention clips made from this grade are evaluated for axial and radial release force before and after thermal ageing. The material should not be used as a direct replacement for POM or PBT in high-stiffness gear wheels or cams without re-evaluating tooth deflection, because conditioned PA12 has a flexural modulus below 1200 MPa, whereas POM is commonly reported above 2500 MPa under ISO 178. The advantage appears in impact-sensitive snap-fits and low-temperature ductility, not in stiffness-limited machine elements.

Compliance status depends on the specific colourant and stabiliser package. Unfilled PA12 grades of this type can be formulated for repeat-use food-contact applications under FDA 21 CFR 177.1500 and for European food-contact use under EU 10/2011, with an overall migration limit of 10 mg/dm². The LM variant must be confirmed against the supplier’s certificate of conformity. Under REACH, the base polymer does not contain substances above the communication threshold of 0.1 % by mass, subject to current SVHC updates. RoHS compliance is generally declared for the restricted substances of Directive 2011/65/EU, including lead, mercury, cadmium, hexavalent chromium, PBBs, and PBDEs at maximum concentration values. For drinking-water contact, region-specific certifications such as ACS, KTW, or WRAS may be required, and continuous water exposure must be validated separately.

Operational boundaries and material incompatibilities

The conditioned property set is reversible. Drying a moulded part at elevated temperature shifts tensile modulus back toward 1400 MPa to 1600 MPa and reduces notched impact toward 5 kJ/m² to 7 kJ/m² under ISO 179/1eA. Snap-fit and living-hinge calculations should therefore use dry and conditioned values as lower and upper bounds rather than a single average. The grade should not be combined with strong acid concentrates, strong oxidising agents, or high-polarity solvents at elevated temperature without compatibility testing. Continuous hot-air service above 100 °C can produce oxidative embrittlement unless a heat-stabilised variant is specified. Flame-retardant packages, when required, must be assessed for plate-out and screw corrosion on hardened tool steel. In injection moulding, hopper moisture above 0.15 % generates steam, splay, and viscosity depression that can cause dimensional variation in multi-cavity tools, particularly in thin-wall snap-fit sections.