EMS-Grivory Grilamid LVX-50H black 9230 is a 50 wt% glass-fiber-reinforced polyamide 12 injection-molding compound supplied as a heat-stabilized, precolored black 9230 grade and characterized in the dry-as-molded state. The ISO 1043-1 designation is PA12-GF50; the “Dry” qualifier indicates that mechanical and thermal data are reported on specimens tested immediately after molding or after limited exposure at 23°C/50% RH, not after equilibrium moisture uptake. This distinction is critical because polyamide properties are strongly dependent on absorbed water. Manufacturer-published data for this exact grade list density at 1.38 g/cm³ under ISO 1183-1, water absorption at 0.5% under ISO 62 at 23°C/50% RH, and dry tensile modulus of approximately 17,500 MPa under ISO 527-1/-2. In comparison, unreinforced PA12 grades commonly show density near 1.01 g/cm³ and tensile modulus below 2,000 MPa in the dry state. The compound is therefore positioned for injection-molded components in which low moisture uptake, chemical resistance, dimensional reproducibility, and high stiffness are jointly specified.

Because the grade contains 50 wt% chopped glass fiber, flow behavior differs markedly from unreinforced PA12. The 50 wt% fiber is incorporated downstream in a co-rotating twin-screw extruder with L/D ratio between 32:1 and 44:1 to limit fiber attrition. Spiral flow length at a 2.0 mm wall thickness is lower than that of unfilled PA12 by approximately 30–50%, depending on melt temperature and injection pressure. Gate locations should be placed to minimize weld lines in load-bearing sections; when knit lines are unavoidable, tensile strength in the weld area may be 40–60% of the un-welded bulk value under ISO 527-1/-2. Molded parts typically show anisotropic shrinkage, with lower shrinkage in the glass-fiber orientation direction and higher shrinkage transverse to flow. Published data for this configuration indicates mold shrinkage in the flow direction near 0.15% and transverse shrinkage near 0.5%, although tool geometry, gate type, and packing pressure shift these values. Because the material is precolored black 9230, colorant addition at the molding machine is not required, avoiding uncontrolled masterbatch dispersion and screw-slippage variations.

Which processing boundary governs the dry-as-molded property set?

Pre-drying is the first boundary. The pellets must be dried to 0.10 wt% moisture or lower before melting; dehumidified-air drying at 80°C for 4–12 h with an inlet dew point of −30°C or lower is standard. Moisture above 0.15 wt% at the hopper produces hydrolysis in the barrel, visible as splay and surface roughness, and reduces notched impact strength by more than 15% in some production runs. The hydrolysis rate of PA12 is lower than that of PA66 because the amide-group density is lower, but the same failure mechanism operates when residence time is long. Melt temperature should be held between 230°C and 260°C. Above 270°C, resin degradation and glass-fiber-matrix debonding lower tensile strength and create gas marks near the gate. Mold temperature is recommended at 80–100°C; cooling below 60°C freezes the surface before interior crystallization completes, producing lower heat deflection temperature and warpage.

Residence time is the second boundary. For machines with shot size above 60% of barrel capacity, residence time should remain below 10 min; if the shot size falls below 25% of barrel capacity, residence time can exceed 20 min, leading to a measurable decline in Charpy notched impact strength. Screw speed and back pressure should be set low enough to limit fiber attrition. Back pressures between 0.5 MPa and 1.0 MPa are commonly used for glass-filled PA12; higher back pressure improves melt homogeneity but reduces average fiber length. Hot-runner channels with diameters below 2.0 mm and gate lands below 1.5 mm generate high shear and may reduce fiber length, which directly lowers tensile modulus from the published 17,500 MPa value.

These values are typical dry-as-molded lot data and are not lot-specific certificates. Conditioning under ISO 1110 to equilibrium at 70°C/62% RH reduces tensile modulus by approximately 5–10% and raises notched impact strength. For design calculations, conditioned values should be used when the part operates for extended periods in humid air.

Comparative Data for PA12-GF50, PA66-GF50, and PPA-GF50

Representative comparison against 50 wt% glass-fiber-reinforced PA66 and polyphthalamide grades is shown below. Reference values are compiled from public technical literature and are not direct lot comparisons.

The density advantage is approximately 0.18 g/cm³ relative to PA66-GF50 and 0.24 g/cm³ relative to PPA-GF50, which becomes significant in high-volume automotive parts where mass reduction is specified. The moisture uptake of PA12-GF50 is roughly one-fifth that of PA66-GF50; this limits post-conditioning modulus loss. However, the thermal limitation is explicit: the HDT/A of 175°C makes Grilamid LVX-50H black 9230 unsuitable for load-bearing underhood parts that experience oil sump temperatures above 150°C, where PPA or PPS grades are specified. For continuous exposure at 180°C, the heat-stabilizer package in the H designation retards oxidation, but published data for this specific configuration at 180°C is limited; PPA-GF50 grades are typically specified for thermal classes above 200°C.

When chemical resistance and moisture stability are weighted above maximum service temperature

End-use environments containing zinc chloride solution, automotive glycol/coolant mixtures, aliphatic fuels, hydraulic oils, and road-salt residues favor PA12-GF50 over PA66-GF50. PA12 has a lower density of polar amide groups, which reduces moisture diffusion and provides stress-cracking resistance to zinc chloride solutions that can embrittle PA66. This is particularly relevant in automotive quick connectors and fuel-line clips exposed to underbody splash. Swelling in 85°C aqueous ethylene glycol solution is lower than PA66-GF50; dimensional change after 500 h is commonly below 1.0% for PA12-GF50, whereas PA66-GF50 may exceed 2.0% depending on coolant composition. Published data for this exact black 9230 grade in all coolant formulations is limited, so component validation must be performed with the production fluid.

The trade-off is thermal load. Components operating in engine compartments where local metal surface temperature exceeds 150°C require PPA-GF50, PPS-GF40, or another high-temperature resin. Grilamid LVX-50H black 9230 should be considered for thermal service up to approximately 120–130°C continuous under unloaded or lightly loaded conditions; above this range, oxidation and crystallization changes require long-term end-use validation.

Typical production components for this grade include fuel-line quick connectors, pneumatic fittings, gearwheels, valve bodies, cable clamps, and sensor housings. In snap-fit closures, design elongation should not exceed 1.0–1.5% in areas containing weld lines because the local elongation at break is lower than the bulk 2.5% dry value. For parts machined or assembled after molding, glass-fiber filled PA12 exhibits lower coefficient of linear thermal expansion than unfilled PA12; published CLTE values for PA12-GF50 are commonly in the range 0.2–0.3 × 10⁻⁴ K⁻¹ parallel to flow and 0.8–1.0 × 10⁻⁴ K⁻¹ transverse to flow. This anisotropy must be included in tolerance stack analyses for parts exceeding 100 mm in length, especially when one side is glass-rich and the opposite side is resin-rich. For cavity pressure-limited molds, peak pressure near 400 bar over a projected area of 250 cm² corresponds to 1,000 kN clamp force; margins below that value produce flash because the semi-crystalline PA12 melt passes through the solidification plateau quickly.

Tooling wear, glass-fiber orientation, and anisotropic shrinkage in injection-molding practice

Molding tools require hardened steel at the gate, runner, and parting line because the 50 wt% glass fiber content produces abrasive wear. Nitrided or bimetallic screw and barrel assemblies are recommended for production runs above 50,000 cycles; nitrided screws may show visible wear in the compression zone after 2,000–5,000 cycles when glass-fiber compounds are processed at high screw speed. The use of screw-tip check rings with glass-reinforced PA12 should include clearance compensation, because glass fibers can pack between the ring and seat and cause inconsistent shot weight. Hot-runner systems should have open-pipe flow channels rather than restrictive dead spots; stagnation zones lead to black specks after color change or long residency.

Glass-fiber orientation governs shrinkage and warpage. Fibers align in the flow direction in skin layers but remain more random in the core. For a 3.0 mm thick plaque, the oriented skin fraction is higher at high injection speed and high mold temperature; this increases the difference between flow-direction and transverse shrinkage. When flatness is critical, gate design should produce a linear flow front rather than radial filling, and packing pressure should be held until gate freeze. Shrinkage differences of 0.1% between flow and transverse directions over a 150 mm dimension produce 0.15 mm of differential movement, which is sufficient to exceed flatness specifications in connector bodies.

Electrical properties for PA12-GF50 are typical for polyamide-based glass-filled compounds: comparative tracking index is approximately 600 V under IEC 60112, volume resistivity is in the range 10¹²–10¹³ Ω·cm under IEC 60093, and dielectric strength is approximately 30 kV/mm under IEC 60243-1. These values support use in low-voltage connectors and sensor housings but do not qualify the material for high-voltage battery components where CTI values above 600 V and lower ionic impurity are required. Regulatory compliance for the black 9230 color lot must be verified against the supplier certificate; the manufacturer datasheet does not list food-contact approvals under FDA 21 CFR or European Commission Regulation 10/2011 for this grade, and end-users should not infer such status from the PA12 polymer class alone.