EMS-Grivory Grilamid® L 20 GM is a 20% glass-fiber-reinforced polyamide 12 injection-molding grade supplied by EMS-CHEMIE AG. The material combines a PA12 base resin with chopped glass-fiber reinforcement at a nominal fiber content of 20% by mass. PA12 is a semicrystalline aliphatic polyamide with lower equilibrium moisture absorption than PA6 and PA66; the glass-fiber phase increases tensile modulus, reduces creep under sustained load, and raises the deflection temperature under load relative to unreinforced PA12. The product is specified for injection-molded components that require dimensional stability in humid, hydrocarbon-containing, or winter-road-salt environments and where unfilled PA12 exhibits excessive deflection or insufficient burst strength.

The grade designation L 20 GM encodes the base polymer and modification. The prefix L identifies the PA12 backbone. The numeral 20 indicates the nominal glass-fiber weight fraction. The suffix GM distinguishes the glass-fiber-reinforced medium-viscosity injection-molding grade from unreinforced PA12 and from impact-modified or extrusion grades within the Grilamid L series. This distinction is relevant for substitution projects because the melt viscosity, shrinkage anisotropy, and mechanical property set differ from both unreinforced PA12 and higher-fiber-content PA12 grades.

What Separates L 20 GM from Other Glass-Filled Polyamides in Humid Service?

Compared with glass-fiber-reinforced PA6 and PA66 grades of similar fiber content, EMS-Grivory Grilamid® L 20 GM exhibits lower equilibrium water uptake. At 23 °C and 50% relative humidity, PA12 absorbs approximately 0.6–0.8% moisture by mass when tested according to ISO 62. Glass-fiber-reinforced PA6 and PA66 typically absorb 2.0–2.8% under the same exposure. The consequence is a smaller moisture-induced dimensional change and reduced plasticization of the amorphous phase. Tensile modulus retention in humid service is therefore higher for the PA12 grade than for short-chain aliphatic polyamides, although the dry tensile modulus of PA66-GF20 remains higher in absolute terms.

The density of L 20 GM is also lower than that of PA66-GF20. Representative density values fall within 1.10–1.13 g/cm³ by ISO 1183-1, whereas PA66-GF20 grades commonly fall within 1.26–1.30 g/cm³. For equivalent component volume, this difference corresponds to a mass reduction of approximately 10–15%. The lower density is a direct consequence of the longer methylene sequence in the PA12 repeat unit and of the lower glass-fiber loading required to reach the targeted modulus range.

In the presence of zinc chloride solutions derived from road de-icing salt, PA12 grades generally show higher resistance to stress cracking than PA6 and PA66. This behavior is relevant for automotive under-hood connectors, cable clips, and sensor brackets exposed to splash and brine spray. The glass-fiber reinforcement in L 20 GM further reduces creep and deformation under clamp load, but the base PA12 chemistry is the primary contributor to zinc chloride resistance. Published data for specific zinc chloride exposure configurations on finished parts is limited; component validation under the end-use salt-spray and thermal cycle specification is required.

Melt Conditioning and Injection Molding Window

Pre-drying is required before melt processing. The material should be dried in a desiccant dryer at 80 °C for 4–6 h to a residual moisture content below 0.10% by mass. Exposure to ambient air above 60% relative humidity for more than 1 h can produce surface moisture uptake sufficient to cause splay, reduced weld-line strength, and minor hydrolytic degradation at melt temperature. Hopper dryers are not recommended as the sole moisture-control method for grades processed in humid plant environments.

The melt-temperature window is typically 230–260 °C. Melt temperatures below 230 °C can increase glass-fiber orientation gradients and reduce weld-line strength; melt temperatures above 260 °C increase the risk of discoloration and molecular-weight loss. The mold-surface temperature should be maintained between 40 °C and 80 °C. For dimensionally stable parts with low post-mold shrinkage, the upper half of this range, 60–80 °C, is preferred. Higher mold temperatures promote crystallization and reduce shrinkage anisotropy but increase cycle time. The injection molding machine should use a three-zone screw with an L/D ratio of 18–22 and a non-return valve suitable for glass-filled polyamide. Barrel and screw wear from the glass-fiber reinforcement may be reduced by specifying bimetallic barrels and hardened screw surfaces.

Residence time at melt temperature should not exceed 10 min. Hot-runner systems should be balanced, with no dead spots, because prolonged residence in hot drops can generate black specks and odor. If re-grind is used in non-appearance components, the addition level is typically limited to 20–25% by mass of the total shot weight, but tensile strength and impact resistance should be re-verified because glass-fiber length decreases with each melt history. Drying of reground material to the same 0.10% moisture limit is mandatory.

In production-scale injection molding, the material exhibits mold shrinkage on the order of 0.4–0.7% in the flow direction and 0.8–1.1% transverse to flow when measured according to ISO 294-4. Shrinkage anisotropy is lower than that of some high-fiber PA66 grades but must be compensated in tool design for flat parts, gear housings, and connector bodies. Gate size and location affect fiber orientation near the gate; premature freeze-off in thin-wall regions below approximately 1.0 mm may reduce reinforcement effectiveness.

In automotive fuel-line connector production, the grade is used for quick-connect fittings, retainer clips, and connector bodies where dimensional stability after fuel exposure is a production acceptance criterion. The glass-fiber reinforcement increases burst-strength margin compared with unreinforced PA12, while the PA12 matrix maintains resistance to automotive fuels, oils, and greases. The material is not, by itself, a substitute for multilayer low-permeation fuel line construction under specifications such as SAE J2260 unless the component design accounts for permeation and evaporative emission requirements.

For pneumatic and industrial air-management systems, L 20 GM is used in fittings, manifolds, and mounting brackets exposed to compressed air, oils, and moisture. The reinforcement reduces thread deformation and creep under tightening torque. Because PA12 has lower moisture absorption than PA6, the dimensional change between dry winter air and humid compressed-air circuits is smaller, which assists thread engagement and seal retention in multi-port fittings.

In cable management and electrical installation hardware, the product is specified for cable ties, clips, and mounting bases that require higher stiffness than unreinforced PA12 but lower moisture sensitivity than PA66. The low water uptake reduces the shift in electrical and mechanical properties after installation in humid environments. Volume resistivity is typical of polyamide insulation grades; however, the product is not a flame-retardant grade and normally achieves only HB classification under UL 94 at common wall thicknesses unless the specific grade is modified.

When Fuel Contact Requires Low Extractables and Chloride Resistance

Polyamide 12 grades such as L 20 GM are selected for fuel-contact components because the longer alkane segments between amide groups reduce the affinity for polar and aqueous media relative to PA6 and PA66. In hydrocarbon exposure, fuel uptake is controlled, and the glass-fiber phase can further reduce continuous-fuel swell because the rigid reinforcement constrains volumetric expansion. Extractables performance depends on the heat stabilization and additive package used in the specific lot; components intended for fuel-contact service should be tested under the relevant OEM fuel aging procedure rather than relying solely on base-polymer data.

Chloride resistance is a second selection driver. Zinc chloride salt exposure can initiate stress cracking in PA66 components under molded-in residual stress, particularly around weld lines, threads, and snap-fit features. PA12 generally has higher tolerance to zinc chloride solutions. In L 20 GM, the retained tensile strength and welded-joint performance should be evaluated on parts because fiber orientation at the weld line reduces local elongation. The material does not eliminate the need for proper gate placement and weld-line positioning.

Operational boundaries apply. Continuous load-bearing service above approximately 80 °C requires creep testing under the actual load and temperature, because the deflection temperature under load is a short-term test and does not establish a long-term service rating. Strong mineral acids, oxidizing acids, and phenolic compounds can degrade PA12. The natural grade is not recommended for outdoor exposure without UV stabilization; black or UV-stabilized variants are required for weatherable applications. The product is not inherently flame-retardant and should not be specified for electrical enclosures requiring V-0 classification at the intended wall thickness unless a flame-retardant variant is confirmed.

Property Profile at 23 °C and 50 % Relative Humidity

Representative property ranges for EMS-Grivory Grilamid® L 20 GM are summarized in Table 1. The values are compiled from manufacturer technical data and should be treated as lot-independent engineering estimates. Design decisions for safety-critical components require lot-specific certification data from EMS-CHEMIE.

Table 2 compares representative ranges for L 20 GM with unreinforced PA12 and glass-fiber-reinforced PA66. The data illustrate the intermediate stiffness position of L 20 GM and its moisture-absorption advantage over PA66.

The comparison shows that PA66-GF20 provides higher dry tensile modulus and a much higher deflection temperature under load, but at the cost of higher density and significantly higher moisture absorption. Unreinforced PA12 offers lower density but insufficient stiffness for load-bearing snaps and threaded fittings. L 20 GM occupies an intermediate position: the modulus is roughly double that of unreinforced PA12, while moisture absorption remains close to unreinforced PA12 levels.

Regulatory compliance for the standard grade is typically assessed under REACH Regulation (EC) No 1907/2006 and the RoHS Directive 2011/65/EU. Automotive applications may require additional OEM-specific testing for thermal aging, fuel immersion, salt-spray exposure, or odor and fogging. The standard natural grade is not a food-contact grade and is not supplied with food-contact statements unless the specific approved variant is ordered. For applications requiring low extractables in potable water or fuel systems, the end-use article must be validated against the applicable national or international product standard.

For injection molders replacing PA66-GF20 with L 20 GM to reduce moisture-induced dimensional variation, tooling modifications may be required because the melt temperature, mold shrinkage, and gate freeze-off behavior differ. Direct drop-in substitution without mold-flow analysis can lead to short shots in thin sections or changes in weld-line position. Shrinkage measurements on a prototype tool and dimensional capability studies under ISO 294-4 conditions are recommended before series production.