EMS-Grivory Grilamid L 25 W 40 NZ is an unreinforced, internally modified polyamide 12 grade supplied in pellet form. The material designation belongs to the Grilamid L series; the suffix W 40 NZ identifies a low-modulus, high-ductility modifier package whose exact chemistry is proprietary to EMS-CHEMIE AG and is not disclosed on the public technical datasheet. The qualifier conditioned does not refer to an additive treatment but to the moisture-equilibrated state of test specimens after storage or accelerated conditioning under ISO 1110 or 23 °C/50 % RH. In this state the resin absorbs approximately 0.9 %–1.3 % water by mass, which suppresses the rigidity of the amorphous phase and produces higher notched impact resistance, lower tensile modulus, and lower yield stress than the dry-moulded condition. Manufacturer-published conditioned values include a tensile modulus near 650 MPa measured by ISO 527-1/-2, yield stress close to 28 MPa, yield strain near 25 %, and nominal strain at break above 50 %. Charpy notched impact strength at 23 °C is approximately 65 kJ/m² under ISO 179/1eA. Density is typically 1.02 g/cm³ by ISO 1183, and the melting peak by ISO 11357-3 is approximately 175 °C.

Because datasheet values derive from conditioned injection-moulded plaques, extruded or blow-moulded performance may differ depending on crystallinity, orientation, and section thickness. The table below summarises the dry-to-conditioned shift in key mechanical responses.

What separates Grilamid L 25 W 40 NZ from unmodified PA12 in conditioned service?

Compared with the same polymer family, this grade is not a direct substitute for unmodified PA12. The internal modifier package reduces tensile modulus in both dry and conditioned states but raises conditioned notched impact from 5 kJ/m² to 65 kJ/m². A standard unmodified PA12 typically retains higher dry modulus and lower moisture-conditioned elongation; its notched impact strength remains below 15 kJ/m² at 23 °C in many supplier datasheets. This shift is relevant in clips and snap-fit designs where low-velocity impact fracture is the dominant failure mode. The modulus reduction, however, also lowers spring retention after assembly. Design calculations based on dry PA12 flexural modulus should therefore be corrected to the conditioned tensile modulus of 650 MPa or lower if the part is exposed to atmospheric humidity.

Relative to PA6 and PA66, PA12 has a lower amide concentration and longer methylene sequences. PA6 at 23 °C/50 % RH absorbs roughly 2.5–3.0 % water; PA66 absorbs approximately 2.0–2.5 %; this PA12 grade absorbs 0.9–1.3 %. The larger moisture uptake of PA6 and PA66 shifts dimensions and reduces modulus more strongly in humid service. Density for PA6 is 1.14 g/cm³ and for PA66 is 1.13–1.15 g/cm³, whereas PA12 remains near 1.02 g/cm³. In tubular applications, the resulting mass-per-metre difference can be significant where line length is fixed. The trade-off is that unmodified PA6 often exhibits higher dry tensile modulus and higher heat resistance, so Grilamid L 25 W 40 NZ should not replace PA6 in load-bearing components above 60 °C without a thermomechanical review of the assembly.

Compared with PA11, the melt peak of this PA12 is lower, near 175 °C, while typical PA11 melts near 189 °C. The lower processing temperature can reduce heat input in coextrusion with heat-sensitive tie layers. PA11 and PA12 both exhibit low moisture uptake, but PA12 typically has lower density and a different crystallisation rate. For this specific grade, the proprietary modifier package dominates the mechanical response; substitution against a generic PA11 tube grade therefore requires pressure-rating and burst testing under ISO 1167 rather than resin-to-resin property comparison alone.

Extrusion and injection molding boundaries for conditioned versus dry feedstock

Pre-drying is mandatory for unopened bags exposed to ambient humidity. The supplier recommends drying at 80 °C for 4–6 h using dehumidified air with a dew point of −25 °C or lower, targeting residual moisture below 0.10 % by Karl Fischer or ISO 15512. Drying above 90 °C risks surface oxidation of the plasticizer package and can reduce notched impact response. Dried pellets should be consumed within 2–4 h; extended hopper residence at high ambient humidity returns moisture to the granule surface and can produce splay in thin-walled or transparent parts.

On single-screw extruders with L/D below 24:1, unmelted pellets can produce pressure pulsation and periodic diameter fluctuation in tubing. A barrier screw with a mixing section is preferred for thin-wall tube at line speeds above 20 m/min; otherwise wall-thickness variation can exceed ±0.05 mm. The viscosity of PA12 is more Newtonian than that of PA66, so high-shear gates do not produce the same shear-thinning correction; runner and gate sizing must account for higher low-shear viscosity. Melt residence time above 260 °C should not exceed 5 min. Longer residence produces yellowing, a measurable drop in Charpy notched impact, and carbon deposits on screw and hot-runner surfaces.

On injection moulding machines with clamp force below 80 t, thin-wall parts can be processed with fast injection speed; however, the low modulus of the conditioned part can mask ejection problems if the cavity is insufficiently drafted. Draft angles of at least 0.5–1.0° are recommended for deep ribs because the material is ductile and can deform during ejection. Hot-runner systems should use externally heated manifolds without dead spots; the plasticized PA12 melt is more sensitive to residence-time-induced degradation than unmodified PA12. At residual moisture above 0.15 %, processing may still be possible, but melt pressure will drop and surface splay can appear. Regrind is typically limited to 20–30 % by weight for critical parts; higher regrind levels reduce impact strength and may alter plasticizer distribution within the melt.

When conditioned PA12 components operate in hydrocarbon and pneumatic systems

The grade is used in pneumatic tube, cable sheathing, hydraulic lines, and snap-fit connectors where conditioned impact resistance and hydrocarbon tolerance are required. The lower equilibrium moisture uptake compared with PA6 and PA66 makes the material suitable for humid industrial air systems, but the plasticizer package raises fuel permeation relative to unmodified PA12. Published data for this specific grade under SAE J2260 fuel permeation are limited, and supplier validation is required before use in evaporative emission lines. Cold impact is reported near 10 kJ/m² at −30 °C, which limits severe cold-puncture applications unless the part is redesigned with a thicker wall or lower stress concentration.

In pneumatic tubing, outside diameter and wall-thickness tolerances are commonly evaluated under DIN 73378 or SAE J844. Burst pressure at 23 °C is influenced by conditioning because moisture reduces tensile modulus. The material's resistance to hydrocarbons such as diesel, hydraulic oil, zinc chloride solutions, and greases is a PA12 attribute; however, the modifier package can increase extraction and swelling in contact with highly polar fluids or fuels containing high methanol concentrations. Published data for this specific grade in continuous alcohol fuel blends are limited, and component validation under end-use fluid exposure is recommended. Stress-cracking resistance to metal halide solutions should be evaluated on pressurised parts rather than on unstressed coupons because the internal plasticizer can alter the stress-cracking threshold.

Dimensional change follows a moisture-dependent sorption profile

After moulding, dry PA12 parts take up moisture and expand. The equilibrium moisture content at 23 °C/50 % RH is approximately 1.0 %; the corresponding linear hygroscopic expansion is typically 0.15–0.25 % relative to dry-moulded dimensions, depending on orientation and wall thickness. This change is largely reversible on re-drying, but repeated cycling between 10 % RH and 90 % RH can induce surface microcracking at metal inserts if the part is over-constrained. Dimensional checks should therefore be made after conditioning, not on dry parts, when using ISO 294-4 shrinkage plaques. For thin-walled snap-fit retainers, the radial force loss after moisture conditioning must be accounted for; the tensile modulus drop from 1100 MPa to 650 MPa can reduce cantilever engagement force by approximately 40 % unless the deflection and retention geometry are recalculated.

Published data for long-term creep at elevated temperature for this specific plasticized PA12 are limited; load-bearing parts should be evaluated by ISO 899 using conditioned specimens rather than relying solely on short-term tensile data. Published data for simultaneous chemical exposure and cyclic humidity for this specific grade are also limited; component validation should use conditioned specimens and the relevant end-use test rather than extrapolating from short-term dry data.