EMS-Grivory Grilamid® L 20 G PA12 is a semi-crystalline polyamide 12 compound reinforced with 20 wt% short glass fibres. Under ISO 1874-1, the material occupies the PA12 family with the GF20 filler designation; the EMS trading designation L identifies the PA12 backbone and G identifies glass fibre. Manufacturer-published typical values report a density of 1.23 g/cm³ according to ISO 1183-1 and a melting endotherm peak near 178 °C according to ISO 11357-3. The grade is used in injection-moulded connectors, pneumatic fittings, cable-protection parts, and extruded profiles where the specification must combine lower equilibrium moisture uptake than PA6 or PA66, resistance to aliphatic hydrocarbons, and improved stiffness over unfilled PA12. Relative to unfilled Grilamid® L 16, the glass-filled variant raises dry tensile modulus from approximately 1,600 MPa to above 4,200 MPa, reduces tensile strain at yield to 4–5 %, and changes moulding shrinkage from the unfilled range of roughly 0.8–1.0 % to a flow-direction range of 0.2–0.4 %. These changes do not move the grade into the thermal class of PPA or PA66; they create a distinct intermediate profile for parts that require glass-fibre stiffness without the dimensional and moisture penalties of short-chain polyamides.

How Does 20% Glass Fibre Alter the Property Profile Relative to Unfilled PA12?

Under ISO 527-1/-2, the dry tensile modulus of the 20 wt% glass-fibre grade is typically reported between 4,200 MPa and 4,500 MPa; after conditioning to equilibrium in a standard laboratory atmosphere at 23 °C and 50 % RH, the value drops to approximately 3,000 MPa. Tensile stress at yield follows a similar trend from near 85 MPa dry to approximately 60 MPa conditioned. The glass reinforcement limits elongation at yield to 4–5 % dry and 8–10 % conditioned. Charpy notched impact strength under ISO 179-1/1eA remains in the 7–9 kJ/m² dry range; the unfilled PA12 grade is more ductile, but the GF20 version is specified where creep under sustained load, thermal expansion, or flexural stiffness must be controlled. Because PA12 has a lower amide-group concentration than PA6 or PA66, the glass-reinforced variant retains lower equilibrium water absorption under ISO 62, typically 1.2–1.5 % at saturation in 23 °C water. Creep and fatigue resistance are not fully specified by single-point tensile values. For components subjected to sustained internal pressure, glass reinforcement reduces maximum deformation under burst load, but burst-pressure testing should still be conducted under the applicable product standard with the relevant pressure-temperature profile. The grade is not a dry-sliding wear candidate against steel or aluminium without a tribological modifier because glass-fibre reinforcement alone does not provide the required wear resistance.

On exposure to 23 °C water to saturation under ISO 62, PA12–GF20 reaches approximately 1.2–1.5 % water uptake. PA6–GF20 grades typically reach 6.0–7.5 % under the same condition, and PA66–GF20 grades reach 4.5–5.5 %. The lower amide-group density of PA12 also reduces the rate and equilibrium magnitude of moisture-induced tensile modulus loss. After standard laboratory conditioning at 23 °C and 50 % RH, the dry tensile modulus of 4,300 MPa falls to approximately 3,000 MPa, while the conditioned tensile stress at yield is near 60 MPa. This is a narrower relative loss than in PA6–GF20, where modulus can fall by more than 30 % from dry to conditioned. For particle-sensitive tolerances, the practical consequence is that PA12–GF20 parts continue to gain small dimensional changes over their first 48–96 h of humid exposure, but the total expansion is lower than that observed in PA6–GF20 components of identical wall section.

When Processing Requires Pre-Drying and Controlled Back Pressure

Pre-drying at 80 °C in a desiccant dryer for 4–12 h is recommended to bring pellet moisture below 0.10 %. In reciprocating-screw injection moulding machines with 20:1–25:1 L/D three-zone screws and compression ratios of 2.0:1–2.5:1, melt temperature is maintained between 250 °C and 270 °C, and the mould surface temperature is controlled between 60 °C and 100 °C. Back pressure is set to 0.5–1.5 MPa, and screw peripheral speed is limited to 0.2–0.5 m/s to control fibre-length retention. Residual moisture above 0.15 % causes hydrolysis, mould deposit, surface splay, and reduced weld-line strength. On single-screw extrusion lines, a grooved feed section and separate temperature zones with a flat profile from 240 °C to 260 °C reduce melt-temperature overshoot. Starve-feeding is not recommended because unmelted glass-fibre bundles can segregate at the compression zone and generate die-lip accumulations. When regrind is added to virgin compound, the level is normally limited to 25 % of shot weight unless tensile impact and notched Charpy data from production trials support a higher ratio. Hot-runner manifold temperatures should not exceed 270 °C to restrict residence-time degradation. Fibre attrition in the screw is not entirely avoidable; production parts with long flow paths may exhibit lower tensile strength at weld lines than datasheet values generated on standard tensile bars.

Thermomechanical Benchmarks Under ISO 527-1/-2 and ISO 75-1/-2

Table 1 summarises manufacturer-published typical values for dry-as-moulded and conditioned specimens. Dry values refer to specimens sealed immediately after moulding; conditioned values refer to specimens stored to equilibrium at 23 °C and 50 % RH according to ISO 1110 atmosphere or equivalent internal conditioning. These are not specification limits and should not be substituted for lot-specific certificate data.

Chemical resistance data for this specific grade should be generated under ISO 175 immersion protocols using the end-use fluid at the relevant temperature because the published datasheet does not cover all service media. Manufacturer screening data for PA12 indicate low swelling in aliphatic hydrocarbons, mineral oils, greases, and zinc chloride solutions at ambient temperature, whereas concentrated mineral acids, polar solvents that dissolve polyamides, and oxidising media above 80 °C require application-specific validation. In fuel-contact applications, PA12 grades are often selected for lower hydrocarbon permeation than PA6 of equivalent wall thickness, but the measured permeation rate depends on test temperature, pressure, fuel oxygenate content, and wall thickness. Published studies under CARB and SAE evaporative-emission test methods report lower fuel permeation for PA12 than for PA6 at comparable wall thickness; however, grade-specific values require part-level testing at the specified service temperature. For drinking-water or food-contact articles, the final component must be assessed against the applicable national regulation or certification scheme because the raw granulate alone does not provide compliance. For EU applications, the resin supplier’s REACH registration does not automatically cover the finished article, and further declarations concerning RoHS Directive 2011/65/EU Annex II substances may be required. Flammability under UL 94 is commonly reported as HB at 0.8 mm; this is not equivalent to a V rating.

Dimensional Stability Is Governed by Moisture Uptake, Not Merely by Glass Loading

At 23 °C and 50 % RH, PA12–GF20 reaches an equilibrium moisture content below 0.8 %. The same environment commonly brings PA6–GF20 to 1.5–2.0 % and PA66–GF20 to 1.0–1.5 %. Because the GF20 compound has anisotropic fibre orientation, moulded parts exhibit differential post-shrinkage between flow and transverse directions. Under ISO 294-4, the flow-direction moulding shrinkage is typically 0.2–0.4 % and transverse shrinkage is 0.4–0.6 %. Post-mould moisture uptake adds 0.05–0.10 % to critical dimensions over weeks, which is lower than the corresponding PA6–GF20 shift but still significant for dimensions tighter than ±0.05 mm. Parts with flatness or roundness tolerances at the edge of process capability should be measured after conditioning, not immediately after ejection. Tools should be designed with a minimum draft angle of 0.5–1.0° and with gates positioned to align fibre orientation with the primary load path; published data for this specific gate-position configuration is limited, so mould-filling simulation is used for confirmation.

Comparative Specification Matrix Across Polyamide Families

Table 2 compares typical published datasheet bands for 20 wt% short-glass-fibre polyamide grades. The values are representative and vary by heat stabilisation, impact modification, and nucleating package. The table does not identify a single competitor grade, but shows the specification trade-off faced in material selection.

The differentiation relevant for part design is that PA12–GF20 offers lower density and lower saturation moisture uptake, while PA6–GF20 and PA66–GF20 provide higher dry modulus and higher heat-distortion temperatures. PPA–GF20 offers the highest thermal capability but requires a higher processing temperature. The penalty for PA12–GF20 is a lower continuous-use temperature and lower dry creep resistance at temperatures above 90–100 °C. Creep-rupture comparisons should be made under ISO 899-1 at the expected service temperature, particularly for clamped or pressure-loaded components.

Assessing the Replacement of Polyphthalamide in Air and Fuel Management Components

Polyphthalamide grades require melt temperatures above 320 °C and mould temperatures of 120–150 °C; PA12–GF20 processes at 250–270 °C. This lower thermal load allows overmoulding with thermoplastic elastomers, thread-forming operations, and spin welding without the same heat input, although it also excludes continuous dry-heat service above 180 °C. In air and fuel management connectors, PA12–GF20 is considered where low water absorption, low hydrocarbon permeation, and resistance to road chlorides are required. The glass fibres reduce creep under clamp load compared with unfilled PA12, while the PA12 matrix provides lower density than PPA. For under-hood parts exposed to sustained temperatures above 150 °C, PPA remains specified because PA12–GF20 loses stiffness and long-term thermo-oxidative stability. The replacement decision should be based on continuous-use temperature, chemical exposure, and wall-thickness-dependent permeation data rather than on single-point tensile strength.

On production-scale injection moulding lines, the main observed failure mode is brittle weld-line fracture in thin sections where glass fibres orient perpendicular to the melt front. Increasing melt temperature from 250 °C to 270 °C and reducing screw peripheral speed from 0.5 m/s to 0.3 m/s improve fibre wet-out but can lower solidification rate. Gate freezing time in a 1.5 mm wall section is short enough that packing pressure must be applied for 2–4 s after velocity-pressure switchover. Uniform cavity temperature within ±5 °C is required to avoid differential crystallisation and warpage. The material should not be purged with PA66 at high temperature without an intermediate polyethylene or commercial purge compound because the melt-temperature and viscosity differences produce mixed-viscosity regions. Ejecting parts above 90 °C into unconstrained bins has been associated with post-mould distortion. The processing window for the grade is therefore compact, and dimensional capability depends on controlling moisture, mould temperature uniformity, and fibre orientation at the gate.