EMS-Grivory Grilamid® LC-15H black is a heat-stabilised polyamide 12 (PA12) compound reinforced with 15% carbon fibre by weight. The grade is designated PA12-CF15 under ISO 16396; the C identifies carbon fibre, the 15 identifies the nominal fibre content, and the H identifies heat stabilisation. The black colour is integral to the carbon-fibre package and is not a surface coating. The compound is intended for injection moulding and, in selected cases, extrusion of semi-finished profiles. Because the matrix is PA12, LC-15H black exhibits lower water absorption, lower density, and lower melt processing temperature than short-chain polyamides such as PA6 or PA66. The carbon fibre contributes high tensile modulus, low creep, reduced thermal expansion, and a semiconductive path through the part. The material is not a high-temperature polyamide and is not formulated as an electrical insulator.

Performance envelope under ISO mechanical and thermal characterisation

Manufacturer-published values for Grilamid® LC-15H black are normally expressed in dry-as-moulded and conditioned states. The dry-as-moulded tensile modulus measured under ISO 527-1/-2 is approximately 8 500 MPa, roughly four to five times the modulus of unfilled PA12. Tensile strength at break is approximately 135 MPa, and elongation at break is limited to approximately 3.0%; the stress-strain curve is nearly linear to failure without a pronounced yield point. Charpy notched impact at 23 °C under ISO 179/1eA is approximately 12 kJ/m², which places the grade in the stiff, low-to-moderate-ductility class rather than in the high-toughness class of unfilled PA12. The density is approximately 1.06 g/cm³ under ISO 1183, which is lower than a comparable 15% glass-fibre-reinforced PA12. The following table summarises these typical values.

Conditioning according to ISO 291 at 23 °C and 50% relative humidity reduces modulus and tensile strength while increasing elongation at break and impact strength. The moisture effect is smaller than for PA6 or PA66 because the PA12 backbone absorbs less water. However, design calculations should use conditioned values when service humidity is not mechanically excluded. The numerical values in the table are representative of the black grade at 23 °C under dry-as-moulded storage. They are not lot-release minima, design allowables, or values to be used for safety factors without supplementary testing. For structural calculations, the supplier’s design manual and a statistically valid data set from the actual production lot should be used. Modulus and strength also depend on wall thickness: very thin walls orient fibre more strongly in the flow direction, producing higher in-flow modulus but lower cross-flow strength. Thick sections with less oriented fibre may show different surface conductivity and shrinkage behaviour. The table does not constitute a specification; lot-specific certificates and the current EMS technical datasheet are controlling.

What processing parameters are critical when moulding LC-15H black?

Pre-drying is mandatory because PA12 is hygroscopic and carbon fibre can carry surface moisture. The granulate should reach a water content below 0.10% by mass, measured by ISO 15512, before melt processing. A desiccant dryer with a dew point below -30 °C is required; drying at 80 °C for 4 h to 6 h from sealed bags is typical. If the material has been exposed to relative humidity above 60%, drying should be extended to at least 8 h. Hopper temperatures above 100 °C are not recommended because oxidative degradation and colour shift may occur. The melt temperature measured by air shot should be 220 °C to 250 °C; barrel settings should progress from approximately 200 °C in the feed zone to 240 °C in the metering zone, with the nozzle at 230 °C to 250 °C. Mould temperature should be held at 60 °C to 80 °C to promote crystallisation of the PA12 matrix and stabilise part dimensions. Residence time in the barrel should be less than 8 min at melt temperature. The carbon-fibre reinforcement raises melt viscosity relative to neat PA12; injection pressure is commonly 20% to 30% higher than for unfilled PA12 of the same wall thickness. Packing pressure should be 50% to 70% of the injection pressure. Back pressure should be low, between 0.5 MPa and 1.5 MPa, to avoid excessive fibre attrition. Screw surface speed for 25 mm to 40 mm diameter units should be limited to 15 m/min to 30 m/min. Wear-resistant screw and barrel materials are required; check rings, nozzle tips, sprue bushes, and gate inserts should be hardened to at least 55 HRC. Vent depths of 0.02 mm to 0.04 mm are used to avoid gas burn. Injection speed should be profiled to fill the cavity rapidly but before flash formation; fast filling improves surface appearance of carbon-filled grades and reduces visible fibre at the surface. Overpacking should be avoided because it increases stress concentration around gates. Hot-runner systems can be used if thermally controlled to 230 °C to 250 °C and fitted with wear-resistant tips. Cold-runner systems for short sprues should use full-round runners of 3 mm to 6 mm diameter and avoid sharp changes in direction. Regrind from sprues and runners can be added up to 20% by weight, but fibre length reduction will lower tensile modulus and impact strength. During shutdown, a PA12 or PA6 purge should be used; olefinic purges that degrade within the processing range are unsuitable. Carbon-fibre grinding, mould cleaning, and part deflashing should be conducted with local exhaust ventilation to control airborne fibre.

Where the part geometry contains knit lines or changes in wall thickness, the mechanical response of LC-15H black is influenced by carbon-fibre orientation. Weld lines do not simply reduce local strength; they also interrupt the conductive fibre network and can create local resistivity variation. Wall sections below 1.5 mm can be filled if flow length is adequate, but injection speed should be raised to keep the melt front above the crystallisation onset temperature of PA12. Gate placement should minimise weld lines in load-bearing regions; when a weld line is unavoidable, the gate location should shift the weld line into a compressive stress field. Carbon-fibre orientation also produces anisotropic shrinkage. In-flow shrinkage is typically 0.30% to 0.50%, while cross-flow shrinkage may be 0.60% to 0.90%. These ranges depend on gate type, part thickness, and packing time, so mould trials are required before tool hardening.

The conductive carbon-fibre network alters electrical behaviour relative to unfilled PA12. Surface resistivity is commonly in the static-dissipative range, and volume resistivity is typically between 10² Ω·cm and 10⁵ Ω·cm, depending on part geometry, fibre orientation, and surface skin. The material must not be used as a high-voltage electrical insulator or in creepage-path features defined by insulation coordination standards unless externally verified. The conductive filler may also affect radio-frequency transparency and antenna performance in structurally integrated designs. Carbon-fibre reinforcement also reduces the coefficient of linear thermal expansion and improves wear resistance in sliding contact. Wear debris from carbon-fibre-filled PA12 is conductive and may not be acceptable in open electronic assemblies; tribological evaluation under ASTM G133 or ISO 7148-2 should be performed with the actual counterface. Published data for this specific compound under sliding wear and high-frequency electrical fields is limited, so application-specific characterisation is required.

If the application is subjected to intermittent hydrocarbon exposure and thermal cycling

Because the matrix is PA12, the compound absorbs less water than PA6 or PA66. Equilibrium water uptake at 23 °C and 50% relative humidity is typically below 0.7%, and water saturation is approximately 1.2% to 1.5% under ISO 62. Moisture acts as a plasticiser and reduces tensile modulus and tensile strength while increasing elongation at break and toughness. Components moulded in LC-15H black therefore show lower stiffness after humid ageing, but the change is smaller than with short-chain polyamides. The PA12 matrix provides good resistance to aliphatic hydrocarbons, mineral oils, greases, and diesel fuels; strong acids, phenols, and certain chlorinated solvents can attack the polyamide. For fuel vapour clips, cable clamps, or underbody brackets, compatibility with the actual service fluid should be tested under stress and temperature because environmental stress cracking cannot be predicted from simple immersion data alone. The heat-stabilisation package permits short-term exposure up to approximately 150 °C. Long-term service above 100 °C requires a thermal ageing study because oxidative degradation reduces ultimate elongation over time. Thermal cycling between -40 °C and 120 °C is generally within the capability of the material; the carbon fibre reduces thermal expansion mismatch against metal inserts compared with neat PA12.

In semicrystalline polyamides, chemical resistance is matrix-dominated, but fibre-matrix adhesion can degrade under hydrolysis at elevated pressure. High-temperature pressurised-water exposure at 120 °C or above should not be assumed safe from standard fuel resistance data. Carbon fibre reduces volumetric swelling caused by absorbed water but does not prevent water absorption. If the component is intended for hot-water or steam-contact service, environmental stress-cracking evaluation under ISO 22088-2 or equivalent should be conducted on moulded plaques. Published data for LC-15H black in prolonged hot-water exposure is limited; design validation requires application-specific testing.

Carbon-fibre loading yields a semiconductive path without sacrificing PA12 chemical inertness

The filler system differentiates LC-15H black from 15% glass-fibre-reinforced PA12. Glass-filled PA12 has a density around 1.20 g/cm³ and is an electrical insulator; carbon-fibre reinforcement lowers density and produces a measurable semiconductive path. In mass-sensitive components, the lower density can reduce part weight by 10% to 15% relative to glass-filled PA12 at the same nominal filler mass fraction. Carbon fibre also increases stiffness per unit density and lowers the coefficient of linear thermal expansion to approximately 40 × 10^-6 K^-1 to 60 × 10^-6 K^-1, compared with 100 × 10^-6 K^-1 to 120 × 10^-6 K^-1 for neat PA12. The trade-off is ductility and weld-line strength; glass-filled and unfilled PA12 are more forgiving where high notched impact or post-yield deformation governs design. Compared with carbon-fibre-reinforced PA66 of similar loading, LC-15H black has a lower melting point and lower water absorption but lower heat deflection temperature. Continuous service above 150 °C is not a suitable target for this grade; PPA or PA46 should be evaluated instead. Within carbon-fibre-reinforced PA12 grades, increasing fibre content from 10% to 20% raises dry tensile modulus and lowers notched impact. The 15% loading is therefore a middle point used where stiffness, static dissipation, and practical weld-line strength are required together. Typical application areas include fuel line clips, cable clamps, pump components, equipment housings, and underbody brackets where static dissipation, low moisture sensitivity, and dimensional stability are needed in a single compound.

Designing for LC-15H black requires account of fibre orientation, anisotropic shrinkage, and conductive filler distribution. Gate location and runner layout should be determined by mould flow simulation using measured viscosity data, not by assumptions from unfilled PA12. The material should not be combined with amine-based flame-retardant masterbatches without supplier validation because polyamide additives can promote degradation. Surface gloss of carbon-fibre-filled PA12 is generally lower than that of glass-filled or unfilled grades unless a specific mould texture or surface treatment is used. For aesthetic mouldings, visible flow lines should be expected and managed through texture, gate position, and fill speed rather than through cosmetic additives. The safety data sheet and the current EMS technical datasheet should be consulted for REACH, RoHS, and application-specific regulatory status; this document does not replace lot-specific certification.