EMS-Grivory Grilamid LVX-65H SST black 9288 is a polyamide 12 injection-moulding compound containing 50% glass fibre by weight. The product is supplied as black-pigmented pellets for high-stiffness structural components. In ISO 1043-1:2011 notation the composition is PA12-GF50. The designation “Conditioned” indicates that mechanical values are reported after moisture equilibration under ISO 1110:2019 at 23°C and 50% relative humidity, rather than after a converter-applied thermal or water treatment. The heat-stabilised package and SST surface designation distinguish the grade from conventional high-glass PA12 materials where moulded-surface fibre read-through, weld-line appearance, or ageing-induced surface haze are not acceptable for visible black parts.

The material is intended for applications in which dry-as-moulded polyamide 12 would lack sufficient rigidity and creep resistance. The addition of 50% glass fibre by weight shifts tensile modulus to approximately 16,000 MPa in dry specimens and 13,500 MPa after conditioning to 23°C/50% relative humidity. This is roughly eight to ten times the tensile modulus of unfilled polyamide 12 and approximately twice that of a typical PA12-GF30 grade. The property shift also changes fracture behaviour: highly glass-filled PA12 fails at low nominal strain, typically between 3% and 5%, whereas unfilled PA12 may exhibit yield elongation above 20%. Component design therefore must use notched impact data and fibre-orientation-sensitive modulus values rather than ductile-resin design rules.

What Distinguishes PA12-GF50 from Unfilled PA12 and Lower-Glass Polyamide 12 Grades?

The 50% glass fibre loading is the controlling variable for both processing and in-service performance. In unfilled PA12, moisture uptake at 23°C/50% relative humidity produces modest flexural modulus loss and an increase in toughness. In PA12-GF50, the same moisture uptake acts primarily at the fibre-matrix interface and in the polyamide matrix between glass bundles. The conditioned tensile modulus remains above 13,000 MPa, but the ratio of conditioned to dry tensile strength is typically 0.80 to 0.85. This ratio is smaller than that of unfilled PA12 because glass fibres carry a larger share of tensile load while the plasticised matrix governs off-axis and interlaminar response. The notched Charpy impact value rises only slightly after conditioning, from approximately 18 kJ/m² to 20 kJ/m² under ISO 179-1/1eA, so the conditioned state does not restore the toughness lost by high glass loading.

Compared with a PA12-GF30 grade, PA12-GF50 increases flexural modulus and tensile strength but reduces flow length, weld-line strength, and surface gloss. The high glass content also increases mould and screw wear. Production experience on reciprocating-screw injection moulding machines shows that screw tip and check-ring wear accelerates when glass content exceeds 40%; hardened tool steels, bimetallic barrels, and wear-resistant screw coatings are specified. The SST designation in EMS-Grivory nomenclature is associated with surface quality improvement in high-glass black grades, reducing the silver-streak and exposed-fibre appearance that is otherwise common with 50% glass loading. Black 9288 is the pigment code, and it should not be assumed to provide a specific surface resistivity or laser marking performance without additional supplier documentation.

Conditioning-Dependent Datasheet Values and Moisture-Related Property Shifts

The following values are representative data derived from injection-moulded specimens prepared to ISO 294-3 and tested using the listed methods. Dry values refer to moulded specimens stored in moisture-proof conditions; conditioned values refer to ISO 1110:2019 equilibrium at 23°C and 50% relative humidity.

Moisture conditioning affects the matrix more than the fibre. Tensile modulus and flexural modulus fall by 10% to 16%, while tensile strength falls by approximately 18%. The strain at break increases only slightly because the dominant failure mechanism is fibre-dominated rather than matrix-dominated. This is a key difference from unfilled or low-glass PA12 grades, which often show larger conditioned elongation increases. For dimensional stability, the low equilibrium moisture uptake of PA12 relative to PA66 is advantageous: PA12-GF50 maintains tighter post-conditioning clearance in assembled housings than a comparable PA66-GF50 grade at the same ambient humidity.

Melt Temperature, Drying, and Fibre Orientation Are Set by the 50% Glass Loading

Residual moisture must be below 0.10% before melt processing. Open-container storage under ambient conditions above 60% relative humidity can exceed this limit within 4 h to 8 h. Pre-drying in a desiccant dryer at 80°C for 4 h to 6 h with a dew point of −30°C or lower is recommended. Drying temperatures above 100°C are not required and may cause pellet surface oxidation or colour drift in black pigmented PA12 if residence time is excessive.

Melt temperature measured at the nozzle should remain between 235°C and 255°C. Barrel settings are typically 230°C in the feed zone, rising to 250°C at the metering zone. Exposure above 260°C can initiate oxidative degradation, producing black specks, viscosity loss, and reduced weld-line strength. Mould temperature should be maintained at 80°C to 120°C. Lower mould temperatures reduce crystallinity, surface finish, and weld-line strength in highly glass-filled PA12. A mould temperature of 100°C is commonly selected for black 9288 visible parts because it improves surface uniformity without requiring long cycles.

Fibre orientation is highly dependent on gate type, wall thickness, and filling pressure. Tensile modulus parallel to flow can be higher than transverse direction values by a factor of 2 or more in edge-gated strips. Finite-element analysis therefore should use anisotropic elastic constants derived from mould-filling simulation, not isotropic datasheet values. Weld lines in 50% glass-filled PA12 may retain only 40% to 60% of the unwelded tensile strength because fibres align parallel to the weld plane rather than across it. Gate placement and melt front meeting angles should be evaluated in short-shot studies before mould texturing is completed.

Injection pressure at transfer is typically 80 MPa to 120 MPa, with holding pressure at 60% to 80% of transfer pressure. Back pressure between 0.5 MPa and 1.5 MPa assists fibre dispersion without excessive fibre length reduction. Screw surface speed should be limited to 0.2 m/s to 0.4 m/s; higher speeds generate shear heating and shorten fibre length. Screw L/D ratio from 20:1 to 24:1 is suitable, but the check ring, screw tip, and barrel must be specified for glass-filled polyamide.

Mould shrinkage is anisotropic. Parallel shrinkage is typically below 0.3% and perpendicular shrinkage is typically 0.5% to 0.8% for a 2 mm plaque moulded at the recommended melt and mould temperatures. However, actual shrinkage depends on gate location, holding time, wall thickness, and fibre orientation. Moulds should be cut steel-safe and adjusted after initial sampling. Post-mould shrinkage after moisture conditioning or elevated-temperature exposure is lower than that of PA66-GF50 because PA12 absorbs less water.

Automotive quick-connector bodies and pneumatic valve housings moulded from this grade exploit the low equilibrium water uptake of PA12 relative to PA66. Dimensional change at 23°C/50% relative humidity is smaller than for PA66-GF50, reducing post-assembly clearance drift in humid environments. The 50% glass fibre content places the material in the high-rigidity segment used for replacement of die-cast aluminium in structural housings, but wall-thickness reduction must be verified by fibre-orientation-dependent finite-element analysis. In fuel-contact components, PA12 has historically been specified because of resistance to alcohol-blended fuels and low-temperature impact after conditioning, but published data for this specific combined fuel/temperature profile is limited and must be confirmed by OEM-specific testing rather than generic chemical-resistance tables.

In pneumatic manifolds, the grade provides dimensional stability and high burst strength when the melt fronts are positioned away from the pressure-bearing cross-sections. Production-scale troubleshooting on four-cavity and eight-cavity tools indicates that vent depth in glass-filled PA12 should not exceed 0.01 mm to 0.02 mm to avoid flash without trapping gas at the flow front. Vacuum-assisted venting is often used on black high-gloss surfaces to avoid burn marks.

When Fuel, Glycol and Thermal Cycling Replace 23°C/50% RH Laboratory Conditioning

Polyamide 12 has lower amide-group density than PA6 or PA66, which reduces equilibrium water uptake and improves chemical resistance to automotive fuels, oils, and greases. The long aliphatic repeat unit also lowers low-temperature brittleness relative to PA66-GF50. However, the glass fibre phase complicates chemical resistance. Hot glycol coolant can migrate along fibre-matrix interfaces and produce microcracking during thermal cycling. Components exposed to hot coolant should be tested under combined thermal cycling from −40°C to 120°C and pressure pulsation, not solely by immersion at constant temperature. This is especially important for glass-filled PA12 because interfacial hydrolysis may not be visible on the surface until a leak path develops.

Compared with PA66-GF50, PA12-GF50 offers lower density, lower moisture uptake, better dimensional stability under humid conditions, and generally better resistance to zinc chloride salt solutions used in winter road environments. It gives up some high-temperature performance: heat deflection temperature at 1.8 MPa is around 170°C dry and 165°C conditioned, whereas high-performance PA66-GF50 grades can exceed 240°C. Continuous-use temperature classifications for PA12-GF50 are commonly below 120°C for load-bearing mechanical applications, but the product-specific relative temperature index must be obtained from the UL 746B yellow card for the black 9288 formulation.

Compared with PPA GF50, PA12-GF50 provides lower water absorption, better hydrocarbon resistance, and generally lower mould density, while PPA GF50 provides higher modulus and better dry-heat performance above 150°C. Selection between PA12-GF50 and PPA GF50 is therefore governed by chemical exposure, moisture conditioning, and peak temperature. For underhood fuel-system bracketry and pneumatic connectors, the PA12 grade is often preferred where alcohol-containing fuel or cold-temperature impact is the dominant requirement. For hot-air ducts or high-temperature structural brackets, PPA or PA66 may be selected instead.

Regulatory documentation for EMS-Grivory engineering resins typically addresses RoHS Directive 2011/65/EU as amended by (EU) 2015/863 and REACH Regulation (EC) No 1907/2006. However, the black 9288 colourant system and heat-stabiliser package must be reviewed against the final application specification. Food-contact, potable-water, and medical uses require separate verification of migration limits and sterilisation resistance. The material should not be combined with amine-based additives or aggressive aqueous acids at elevated temperature because polyamide 12 can undergo hydrolysis or chain scission. Published data for this specific configuration under continuous hot-water exposure above 80°C is limited.

In fuel-line quick connectors, burst strength after thermal ageing is sensitive to moisture-conditioned weld-line integrity. Mould filling should position knitted flow fronts in low-stress regions. Tool trials on production machines with clamp force calculated at 8 kN/cm² to 10 kN/cm² of projected area have shown that maintaining clamp force during packing is more critical than peak injection pressure. Premature gate freeze can starve shrinkage and produce microvoids at the fibre-matrix interface, reducing burst pressure by more than 30% in conditioned assemblies. Gate diameter for this grade should be at least 70% of the local wall thickness to delay freeze-off.