EMS-Grivory Grilamid L 20 G Dry is a glass-fiber-reinforced polyamide 12 injection-molding grade containing 20% glass fiber by weight. In the Grilamid nomenclature, L denotes the PA12 backbone, 20 the nominal glass-fiber weight fraction, and G the glass reinforcement; the Dry suffix indicates packaging in moisture-barrier liners with a residual moisture specification below 0.10% by weight when measured by Karl Fischer titration according to ISO 15512. The dry condition is a processing state, not a chemical modification of the polymer. The product is intended for components where low moisture uptake, low density, dimensional reproducibility, and sub-zero impact retention are more important than the higher dry stiffness of glass-filled PA6 or PA66 grades.

The primary specification boundaries include a melt temperature near 176°C by differential scanning calorimetry per ISO 11357-3, a dry density of approximately 1.11 g/cm³ by ISO 1183, and equilibrium moisture absorption at 23°C and 50% RH of approximately 0.16% by ISO 62. The glass-fiber reinforcement reduces dry tensile elongation and raises thermal distortion resistance relative to unfilled PA12. Typical processing and property data are provided in subsequent sections; product-batch certificates should govern because color and additive systems shift the values.

During manufacture, the PA12 matrix is compounded with chopped glass fiber on a co-rotating twin-screw extruder having an L/D of 36:1 to 44:1. Fiber is introduced through a side-feeder after the polymer melt seal is established, and vacuum venting at -0.08 MPa reduces residual moisture before the pelletizing head. The melt temperature at the die is held within 240–260°C to limit thermal degradation while achieving fiber wet-out. Pellet moisture is then reduced to below 0.10% in a dehumidified-air dryer before moisture-barrier packaging. These compounding conditions control fiber length retention, which in turn affects notched impact; severe screw kneading reduces mean fiber length and lowers impact, while insufficient mixing produces visible glass bundles at the pellet surface.

What Distinguishes Dry-As-Molded PA12 GF20 from a Conditioned Pellet?

The dry state differs from a conditioned state primarily in modulus, elongation, and notched impact. In dry-as-molded form, the tensile modulus is typically in the range 3,200–3,800 MPa when tested according to ISO 527-1/-2. After conditioning to equilibrium at 23°C and 50% RH, the polyamide 12 matrix plasticizes, and tensile modulus shifts downward by approximately 20–30% while notched Charpy impact at 23°C may increase by a similar order. Published data for the exact conditioned counterpart of this grade is limited; the general behavior follows the polyamide 12 family response described in ISO 1110 conditioning practice. The dry designation is therefore selected when first-shot rigidity, dimensional repeatability after molding, and avoidance of uncontrolled moisture gradients are specified before the part reaches service equilibrium.

Because PA12 absorbs less water than PA6 or PA66, the dry-as-molded property advantage is smaller than in short-chain polyamides. The moisture-induced glass-transition depression and modulus shift still occur, but the equilibrium moisture content remains lower. At water saturation at 23°C, the moisture uptake is approximately 1.4% by ISO 62, compared with 5–7% for glass-filled PA6 and PA66 compounds. A molded part from this grade does not become hydrolytically unstable at room temperature; however, processing with moisture above 0.10% creates splay, screw lubrication instability, and molecular weight loss at the melt. The dry condition should therefore be preserved through the hopper, not treated as permanent after the liner is opened.

Representative Dry-As-Molded Property Set and Test Designations

The values are representative dry-as-molded data from technical literature for natural grade; they are not batch specification limits. Pigmentation, heat stabilizers, and release agents alter shrinkage and impact behavior. Where the application requires a notched impact value at -40°C, the material certificate must be consulted because low-temperature fracture data depend on glass-fiber length distribution and mold orientation.

Before injection molding, the moisture state of the pellets must be verified. If the barrier liner has been open longer than 4 h at relative humidity above 60%, re-drying is mandatory. A dehumidified air dryer operating at 80°C for 4–6 h with a dew point no higher than -20°C is specified. Drying temperatures above 100°C cause pellet agglomeration, while residence times beyond 8 h at the upper drying temperature can oxidize the pellet surface and shift melt viscosity. The hopper should be blanketed with dry air or nitrogen on production lines where ambient relative humidity exceeds 70%.

When 20% Glass Filler Alters Shrinkage Anisotropy in Multi-Cavity Tools

Glass-fiber orientation during injection molding makes shrinkage directionally anisotropic. Flow-direction shrinkage near 0.3% and transverse shrinkage near 0.7% are typical when measured on a 60 mm × 60 mm × 2 mm plaque in accordance with ISO 294-4. Gate location, wall-thickness transitions, and fiber orientation control cavity-to-cavity variation more than resin lot changes. A mold temperature of 40–80°C is required; mold temperatures below 40°C produce premature crystallization during filling and increase post-molding warpage in thin-wall sections. In multi-cavity tools, the melt cushion should be held at 2–4 mm. Larger cushions increase residence time and create gate-area fiber segregation, while smaller cushions produce short-shot variation.

Melt temperature of 220–250°C is the standard processing window. Below 220°C, glass-fiber dispersion at the gate can produce surface frost and non-uniform fiber distribution. Above 260°C, degradation accelerates; resin yellowing and deposit formation on hot-runner tips are observed at residence times above 10 min. If the hot-runner manifold zone overshoots by more than 5°C, residence time should be reduced below 8 min. General-purpose injection screws with L/D 20:1 to 25:1 and compression ratio 2.0:1 to 2.5:1 are used in production, but screw and check-ring wear in glass-filled grades must be controlled. Check-ring radial clearance should remain below 0.12 mm to prevent melt leakage and inconsistent shot mass. For hot-runner molds, valve-gate orifices of 0.8–1.2 mm are common; orifice diameters above 1.5 mm increase drool at the gate.

With a mold temperature of 60°C and a hold time of 5–8 s/mm² of wall cross-section, parts with 1–2 mm wall show dimensional repeatability within ±0.05 mm in flow direction and ±0.10 mm transverse across a 32-cavity manifold. If the mold temperature is not controlled zonally, shrinkage difference between center and end cavities can exceed 0.15%. The coefficient of linear thermal expansion in flow direction, measured according to ISO 11359-2, is approximately 5 × 10⁻⁵ K⁻¹; the transverse value is higher. This thermal expansion difference must be accounted for in steel-overmolded inserts to prevent edge cracking at gate regions.

Applications for Grilamid L 20 G Dry include pneumatic connectors, fuel-system clips, cable harness fasteners, sensor housings, and structural brackets where aliphatic hydrocarbon contact and low humidity-driven dimensional change are required. The low equilibrium moisture absorption at 23°C/50% RH of approximately 0.16% makes the grade appropriate for dimensional stability across seasonal humidity cycles. In fuel-line clips and connectors, the PA12 backbone provides resistance to diesel, gasoline, and mineral-oil-based greases; published data for long-term exposure of this specific grade to ethanol-blended fuel at high temperature is limited, and component validation according to end-use pressure and temperature cycles is mandatory.

Moisture Uptake and Thermal Stability Compared with PA6 and PA66 Glass-Fiber Grades

The product differs from glass-filled PA6 and PA66 primarily in moisture uptake, density, and thermal distortion. PA6 GF20 and PA66 GF20 offer higher dry tensile modulus and higher heat deflection temperature, but their higher equilibrium moisture absorption leads to larger property shifts from dry to conditioned service. The comparison below uses representative literature values for glass-filled compounds; the specific EMS-Grivory batch certificate governs the product.

The lower density of PA12 GF20 provides mass reduction at equal wall stock compared with PA6 and PA66 glass-fiber compounds. The trade-off is a lower heat deflection temperature and lower dry tensile modulus. Compared with unfilled PA12, the 20% glass reinforcement raises heat deflection temperature at 1.8 MPa from approximately 55°C to 160°C and reduces tensile elongation from a ductile unfilled value above 200% to a semi-brittle dry value near 5%. This means the grade is not selected for high-strain snap-fit designs that require large insertion deflection; it is selected for stiff, dimensionally stable brackets and connectors.

Chemical incompatibility boundaries include concentrated sulfuric acid, formic acid, phenol, and strong oxidizing agents. These media degrade the polyamide backbone and produce surface etching and stress-crack growth. Contact with chlorinated solvents under stress should be avoided. Aliphatic hydrocarbons, petroleum greases, diesel, and dilute alkaline solutions are generally compatible. For metallic chloride service, stress-cracking evaluation should follow ISO 22088-1; published data for this specific grade under zinc chloride road-salt solutions is limited. Hot water and acidified coolant at temperatures above 120°C require component-level validation because hydrolysis alters molecular weight and short-term tensile strength.

Regulatory Approvals Do Not Transfer Automatically to Glass-Filled Grades

REACH registration for the PA12 matrix is maintained by the supplier, but the glass sizing, pigments, and additives are composition-dependent. Food-contact status is not automatic for glass-filled grades. If food-contact evaluation is required, the base polyamide 12 may be assessed under 21 CFR 177.1500 for nylon resins; however, the fiber sizing and colorant system must be covered by a food-contact suitability statement. European food-contact testing under Regulation EU 10/2011 must be performed on the final article because migration values depend on wall thickness, contact time, and food simulant. RoHS Directive 2011/65/EU compliance must be verified on the homogeneous material of the final component. A UL yellow card is grade-specific and cannot be assumed from the base polymer. If used in medical device housings, the material must be assessed under ISO 10993-1 for biocompatibility; the glass fiber and additives are not automatically covered by the base polymer’s USP Class VI listing. Component validation under final use conditions therefore remains mandatory.