EMS-Grivory Grilamid LV-15H nat is a natural-colour polyamide 12 compound containing 15% by weight glass fibre reinforcement and a heat-stabilisation package. Conditioned data refer to test specimens exposed at 23 °C and 50% relative humidity until mass equilibrium according to ISO 1110; the dry-as-moulded state is reported separately because absorbed water acts as a plasticiser in polyamides. The grade is classified under ISO 16396-1 as a glass-fibre-reinforced, heat-stabilised PA12 injection moulding and extrusion material. The long-chain aliphatic backbone provides lower equilibrium moisture uptake than short-chain PA6 or PA66 at the same fibre content; typical water absorption at 50% relative humidity is below 0.8% by mass, while water saturation in water at 23 °C is approximately 1.4%.

The uncoloured nature of the grade avoids carbon black or organic pigments that can alter nucleation, crystallisation rate, and weld-line strength. Downstream colouring or laser marking is possible, but any colourant masterbatch changes melt rheology and should be validated for fibre dispersion and impact retention. Published data for this specific configuration is limited for certain fuel-pulse and thermal-management applications, so component validation should include end-use media exposure rather than relying solely on generic datasheet values.

How does absorbed moisture shift the short-term mechanical profile of this 15% glass-filled PA12?

Absorbed water reduces the glass transition temperature and tensile modulus while increasing elongation at break. Supplier literature typically reports a conditioned tensile modulus of approximately 2,000 MPa versus a dry value near 3,200 MPa when tested to ISO 527-1/-2. Tensile stress at break in the conditioned state is generally reported near 70 MPa, while elongation at break increases to approximately 6–10% from the dry-state range of 3–5%. Flexural modulus shows a corresponding downward shift. Charpy notched impact strength at 23 °C measured to ISO 179/1eA is typically in the range 7–10 kJ/m², indicating moderate toughness retention despite the fibre reinforcement.

The values in the preceding table are typical datasheet figures and should not be used as specification limits. Batch-release testing follows the manufacturer’s ISO 9001-registered procedures. The difference between dry and conditioned tensile modulus is particularly relevant for press-fit connectors and snap-fit features that rely on stiffness and recovery after moisture equilibration.

Melt processing on injection moulding machines with a three-zone screw of 20:1–25:1 L/D and a non-return valve is typical. A compression ratio of 2.5:1–3.0:1 is preferred; high-compression screws designed for amorphous resins can impose excessive shear heating. A screw speed of 80–120 rpm with back pressure of 5–15 bar is a practical starting range. Higher back pressure improves fibre wet-out but may reduce fibre length and impact performance. Pre-drying of sealed bags is not required if packaging integrity is maintained; once opened, exposure to ambient air above 50% relative humidity requires desiccant drying at 80–90 °C for 4–8 h with a drying air dew point of -40 °C or lower to reach residual moisture below 0.10% before melt processing.

The melt temperature window typically spans 250 °C to 270 °C. Barrel profile set points from rear to nozzle are commonly 230 °C, 250 °C, 260 °C, 265 °C, and 260 °C. Mould temperature should be held between 60 °C and 80 °C to balance crystallisation rate and dimensional stability; lower mould temperatures reduce cycle time but decrease spherulitic uniformity and increase post-mould warpage. Higher mould temperatures increase crystallinity, improve dimensional stability, and reduce post-mould sink. Residence time above 290 °C should be kept under 5 min because thermal degradation of the polyamide backbone accelerates.

Production-scale observations on hydraulic injection moulders with clamp forces of 80–120 tonnes show that screw recovery time increases when the feed throat is not cooled adequately, causing glass-fibre bridging at the hopper throat. Batch-to-batch viscosity shifts of approximately ±5% can be observed due to fibre sizing lot changes; moulders should monitor injection pressure and cushion rather than barrel temperature alone. Vent depths below 0.02 mm or blocked vents produce gas burn marks and short shots in thin-wall sections. Deeper vents may flash because the melt viscosity is low.

When the 15% glass fibre level is selected instead of unfilled PA12 or 30% glass-filled PA12

Compared with unfilled PA12, the 15% glass fibre reinforcement raises tensile modulus and heat deflection temperature while reducing the coefficient of linear thermal expansion from approximately 110 × 10⁻⁶ K⁻¹ to 70–80 × 10⁻⁶ K⁻¹ in the flow direction, measured according to ISO 11359-1/-2. Creep under constant stress is also reduced. The trade-off appears as lower elongation at break and reduced weld-line strength in multi-gated geometries. At a wall thickness of 2 mm, the 15% grade typically shows mould shrinkage of 0.4–0.6% parallel to flow and 0.7–0.9% transverse to flow under ISO 294-4. The resulting anisotropy ratio of approximately 1.5 is lower than that of 30% glass-filled PA12, which can show anisotropy ratios above 2.0 due to greater fibre orientation. This lower anisotropy makes the 15% grade more suitable for round connectors and cylindrical bushings where differential shrinkage causes ovality.

When compared with a 30% glass-filled PA12, the 15% grade exhibits lower melt viscosity, lower density, improved surface finish, and reduced fibre anisotropy; weld-line strength and thin-wall flow length are generally improved. The 30% grade provides higher stiffness and better creep resistance but requires greater attention to gate position, venting, and tool wear because higher glass content accelerates abrasive screw and mould wear.

Chemical resistance, thermal ageing, and long-chain polyamide microstructure

Polyamide 12 has a lower amide group density than PA6 or PA66, which reduces equilibrium water uptake and the plasticising effect of absorbed moisture. This microstructure also gives lower susceptibility to hydrolysis in hot water and steam than short-chain aliphatic polyamides. At 15% glass fibre, the compound retains the solvent and fuel resistance of PA12 while gaining stiffness. The heat-stabilisation package is intended for elevated-temperature service, but long-term thermal ageing above 150 °C results in oxidative embrittlement and gloss loss in natural-colour unpigmented grades unless stabiliser content is confirmed by the supplier. Continuous service temperature is not a single datasheet value; thermal ageing programmes for service life prediction typically follow IEC 60216-1 or ISO 527-1/-2 after oven exposure.

Exposure to strong acids, phenols, or concentrated formic acid attacks the polyamide matrix. Hot glycol in electric vehicle thermal management circuits requires component testing because hydrolysis and plasticisation can reduce tensile strength over time. Compared with a 15% glass-filled PA6 or PA66, the PA12 base lowers saturated water absorption to approximately 1.4% against roughly 9–10% for PA6 in water at 23 °C. This difference reduces swelling, hydrolytic chain scission, and the shift in glass transition temperature in humid environments. Short-chain polyamides often display higher dry tensile strength at equivalent glass content, but lose a larger fraction of that strength after conditioning.

Automotive quick connectors, truck pneumatic brake tubing, cable conduits, and fluid reservoirs are candidate applications. In truck air-brake lines, dimensional stability over -40 °C to 125 °C service temperatures and resistance to zinc chloride from road salt are common OEM requirements; component testing to the relevant OEM specification is required. The grade’s low moisture uptake reduces swelling and helps maintain clamping force in press-fit connectors, but component-level pull-out force testing is required. In fuel system components, validation must include alcohol and biodiesel exposure; long-chain PA12 resists hydrocarbons under standard service conditions but is not universally resistant to high-temperature acidic fuels or aggressive biodiesel oxidation products. Published data for this specific configuration is limited for some SAE J2045 and SAE J2260 component tests, and component-level certification must be performed on the final geometry and wall thickness.

Regulatory data in supplier documentation commonly references REACH (EC 1907/2006) and RoHS (Directive 2011/65/EU) absence of restricted substances in the homogeneous natural resin; no intentionally added substance of very high concern above 0.1% w/w is declared. Food-contact suitability under FDA 21 CFR 177.1500 and EU Regulation 10/2011 must be confirmed from a current compliance letter because glass fibre and heat stabiliser additives are subject to migration and specification restrictions. Electrical connectors benefit from PA12’s lower moisture-dependent dielectric shift; however, glass fibre reduces surface resistivity and increases dielectric constant compared with unfilled PA12. Comparative tracking index to IEC 60112 should be verified for live-part spacing. Hydrocarbon permeation is commonly measured to SAE J1737 or OEM cup tests; the glass fibres increase tortuosity but incomplete coupling can introduce interfacial wicking. The natural-colour grade is used in multi-cavity tools with nominal wall sections down to 0.8 mm; thin-wall filling must be confirmed by spiral-flow testing to ISO 294-5 because gate geometry and fibre orientation control effective flow length. For laser marking, contrast on unpigmented material is lower than on black grades; a black laser-additive masterbatch is often added at the moulding machine when high-contrast marking is required.