EMS-Grivory Grilamid LBV-50H FWA nat is a natural-coloured polyamide 12 injection-moulding compound reinforced with a nominal glass-fibre content of 50% by mass. Under ISO 1043-1 the material is designated PA12-GF50. The FWA suffix identifies the product as a candidate for food-contact and drinking-water components, with final conformity evaluated on the finished article. The term Dry in the designation refers to the moisture state used for datasheet mechanical data, normally a moisture content below 0.1% by mass, rather than a permanent service condition.

Representative dry-state datasheet values include a density of approximately 1.45 g/cm³ to ISO 1183, a tensile modulus of approximately 16,500 MPa according to ISO 527-1/-2, tensile strength at break of approximately 190 MPa, elongation at break of approximately 2.5%, and notched Charpy impact strength at 23 °C of approximately 18 kJ/m² to ISO 179/1eA. The melting point by differential scanning calorimetry to ISO 11357 is approximately 176 °C, and the heat deflection temperature under 1.8 MPa to ISO 75-1/-2 is approximately 175 °C. These values are typical and are not specification limits; fibre orientation, moulding parameters and moisture absorption shift the service response.

The high glass-fibre mass fraction imposes a clear processing boundary. Melt viscosity is higher than that of unfilled PA12 and PA12-GF30; therefore screw torque, injection pressure, gate geometry and venting must be sized for a low-flowability, abrasive melt. Desiccant pre-drying at 80 °C for 4 to 8 h to a moisture content below 0.1% is recommended before moulding. Melt temperatures from 250 °C to 280 °C and mould temperatures from 80 °C to 120 °C are typical for production-scale injection moulding; residence time above 280 °C should be limited to prevent thermal degradation. Surface moisture levels above 0.1% can cause splay, embrittlement and loss of surface gloss. Because the compound is abrasive, non-return valves, screw tips and barrel linings should be specified with wear-resistant coatings or hard-metal construction.

How does 50% glass-fibre loading alter the failure envelope relative to unfilled PA12?

Relative to unfilled PA12, the 50% glass-fibre compound raises dry tensile modulus from roughly 1,400 MPa to above 16,000 MPa and tensile strength from around 45 MPa to approximately 190 MPa. The strain at break falls from more than 200% in unfilled PA12 to about 2.5% in the dry-as-moulded state. This is a change from ductile yielding to localised brittle fracture; components must be designed with radii, rib proportions and gate locations that do not rely on large plastic deformation. The notched Charpy impact strength of the reinforced grade is moderate but lower than that of impact-modified or unfilled PA12, so thin walls and sharp notches become limiting features.

Creep resistance under sustained load improves because the glass fibres restrain the amorphous and crystalline domains of the PA12 matrix. Published comparative creep data for this specific filled grade are less extensive than short-term tensile data, so long-term load cases should be supported by component testing to ISO 899 or by finite-element analysis using measured temperature-dependent modulus data. Compared with a 30% glass-fibre PA12, the 50% filled grade provides higher modulus, higher strength and higher heat deflection temperature, but lower elongation and lower impact. The difference is not linear with fibre content because fibre packing, fibre-length retention and weld-line integrity become more influential at higher loadings. At 50% glass, the moulded part is more sensitive to flow-front meeting angles, and weld-line strength may be reduced substantially relative to the unfilled matrix.

Production-scale injection moulding of PA12-GF50 has specific equipment requirements. Injection-moulding screws with a length-to-diameter ratio of 20:1 to 24:1 are common, and glass-filled formulations use moderate to low compression ratios and wear-protected screw surfaces to limit fibre breakage. In twin-screw compounding, glass fibre is typically fed downstream into a polymer melt through a side feeder to preserve fibre length; a screw L/D ratio of 32:1 to 48:1 is used with a vacuum vent to remove volatiles. In injection moulding, back pressure above 1.5 MPa may increase fibre attrition and reduce final tensile modulus, while excessively low back pressure may lead to non-uniform glass distribution. Peripheral screw speeds from 0.1 m/s to 0.3 m/s are typical for 50% glass-filled polyamides.

On production-scale equipment, the primary failure modes observed for 50% glass-filled PA12 are screw-flight wear, hot-runner blockages caused by fibre accumulation, and surface defects from trapped volatiles. Hot-runner manifolds should have polished channels with no sharp corners and should be designed for shear rates below 100,000 s⁻¹ to avoid fibre-matrix separation. Gate shear rates for glass-filled polyamides are typically limited to 20,000–50,000 s⁻¹ at the gate; exceeding this range can cause melt burn, splay or exothermic degradation. Mould venting depths below 0.02 mm are used to allow gas escape without flash.

Fibre orientation across a moulding is heterogeneous. The skin layer, with high shear near the frozen wall, aligns fibres along flow, whereas the core layer may exhibit transverse orientation. This skin-core morphology creates differential shrinkage and warpage in flat parts. Mould filling with multiple gates produces weld lines where the local strength can drop to 40–60% of the un-welded tensile strength for highly filled polyamides; for structural parts, weld-line placement should be validated by short-shot studies and mechanical testing. In flow direction, moulders may observe post-moulding shrinkage from 0.1% to 0.3%, while transverse shrinkage can reach 0.4% to 0.7%. Dimensional checks should be performed after conditioning to moisture equilibrium.

The mechanical data reported for Dry mouldings cannot be transferred directly to water-contact service. As moisture is absorbed, the tensile modulus of the composite decreases, although the effect is smaller than for PA6-GF50 or PA66-GF50 because PA12 absorbs less water. Water absorption at saturation in 23 °C water is approximately 0.9% by mass to ISO 62, whereas PA66-GF50 may absorb roughly 4.5%. The smaller dry-to-conditioned modulus shift makes the grade suitable where water contact and dimensional stability interact. In plants where ambient relative humidity exceeds 60%, sealed packaging and desiccant drying are mandatory handling controls, because surface moisture pickup can occur before the material reaches the hopper.

Chemical resistance of PA12-GF50 is dominated by the semi-crystalline PA12 matrix. The material resists many aliphatic hydrocarbons, oils, greases and zinc chloride solutions, and is less hygroscopic than PA6 or PA66. It is not recommended for continuous exposure to concentrated formic acid, hydrochloric acid, or strong oxidizing media at elevated temperature. When disinfectants are used in water systems, compatibility of the specific disinfectant concentration and temperature must be verified by exposure testing to ISO 175, because oxidative disinfectants can cause surface microcracking over time.

The H designation indicates heat stabilisation. Short-term thermal resistance is reflected in the melting point and heat deflection temperature, but continuous service temperature depends on oxygen access, wall thickness and load. For heat-stabilised PA12-GF50, continuous-use temperatures in air are commonly limited to 80–120 °C depending on load and exposure time; applications above this range should be supported by oven-aging studies with tensile strength retention measured to ISO 527 after defined exposure intervals.

Compared with black-pigmented PA12-GF50 grades, the natural FWA version avoids carbon black and organic pigments, which simplifies migration evaluation but reduces inherent ultraviolet screening. Outdoor components therefore require additional UV stabilisation or a protective coating unless service is indoor or intermittent. Rheology acceptance is typically performed by capillary viscosity rather than melt flow rate because the glass fibres make melt flow-index less representative. A capillary shear rate of 1,000 s⁻¹ near the expected injection shear rate is more informative for lot-to-lot viscosity control.

Regulatory evaluation and water-contact compliance constraints for FWA grades

The FWA designation does not constitute an autonomous food-contact certificate; it identifies a formulation intended for evaluation under relevant food and water-contact legislation. Final compliance is determined by the finished article, including geometry, moulding conditions and any post-processing. The base polyamide 12 may be evaluated under Regulation (EC) No 1935/2004, Regulation (EU) No 10/2011 and, for certain export markets, 21 CFR 177.1500. For drinking-water components, national or regional protocols may require additional analysis of total organic carbon migration, odour and flavour, and microbial growth potential. The natural colour designation is significant in this context because it avoids pigment-related migration variables.

Melt-temperature and residence-time control have regulatory as well as mechanical consequences. At elevated temperatures, polyamide 12 can form oligomeric laurolactam and oxidative by-products; these low-molecular-weight fractions can contribute to total organic carbon migration and organoleptic effects in drinking-water applications. Consequently, hot-runner temperatures should not exceed the upper melt-temperature limit, and hot-runner channels should avoid dead spots that allow slow material recirculation. Batch-to-batch variation in glass fibre length distribution can affect impact and tensile strength; incoming material should be controlled by capillary viscosity or melt flow rate, and moulders should monitor injection peak pressure as an indirect indicator of viscosity shifts. If peak pressure changes by more than 10% at constant melt temperature, the drying state, barrel temperature calibration, or material batch should be investigated.

Typical industrial uses include potable-water pump housings, valve bodies, filter caps, flow-meter chambers, impellers and structural food-contact machine components. In these uses the material is selected over reinforced PA6 or PA66 where lower water uptake, better dimensional stability in wet-dry cycling and lower density are required. It is less suitable than unfilled PA12 for snap-fit or living-hinge components that demand high elongation, and less suitable than polyphthalamide or polyphenylene sulphide for continuous exposure above 180 °C. The high glass content also makes the material unsuitable for thin-wall parts with wall sections below approximately 1.0 mm unless flow simulation and prototyping confirm complete filling.

Operational boundaries include the avoidance of strong mineral acids, concentrated oxidising disinfectants, and polar phenolic solvents at elevated temperature. In hot-water service above 80 °C, hydrolysis resistance is adequate for many non-pressurised potable-water components, but the service life must be qualified for the specific geometry, stress state, disinfectant exposure and temperature cycle. Published data for this specific configuration under continuous pressurised hot-water ageing is limited, so component-level testing under ISO 9080 or an equivalent creep-rupture methodology is required for pressure-bearing parts.