EMS-Grivory Grilamid LV-65H SST nat is designated under ISO 1043 as PA12-GF65, a polyamide 12 matrix reinforced with 65% glass fibre by weight. The product is supplied in natural grade and is characterized in the conditioned state, meaning that reported values represent a specimen equilibrated according to ISO 1110 at 70 °C and 62% relative humidity. The suffix SST in the supplier nomenclature denotes a property-specific stabilization package; nat indicates that no additional colourants are present. Under ambient conditions at 23 °C and 50% relative humidity, unreinforced PA12 reaches an equilibrium moisture content of approximately 0.7–0.8% by mass; the glass-filled compound absorbs less absolute moisture because the glass fraction does not absorb water. Published data for this specific configuration is limited, so the current EMS-Grivory technical datasheet should be consulted for lot-specific moisture limits, glass-sizing chemistry, and actual tensile modulus values.

In injection moulding trials on 100-tonne to 200-tonne machines with 25 mm to 40 mm diameter reciprocating screws, the compound exhibits high viscosity and abrasive wear characteristics. Mould filling requires medium-to-high injection velocities above 100 mm/s screw travel, while hold pressures in the range 60–80 MPa are needed to compensate for the packing density of the glass fraction. Mould temperature control from 80 °C to 120 °C is recommended to obtain a resin-rich surface over the glass fibres and to reduce internal stress. The material is normally dried in a desiccant dryer with a dew point below -30 °C at 80–90 °C for 4–8 h before processing. Excessive residence time above 260 °C can cause discolouration in natural grades and thermal degradation of the polyamide matrix.

Why does the 65 wt% glass fibre loading separate Grilamid LV-65H SST nat from lower-filled nylon 12 grades?

Under ISO 527-2 at 23 °C, glass fibre loading from 30% to 65% in PA12 raises tensile modulus from approximately 8,000–10,000 MPa to a supplier-published range of 17,000–21,000 MPa for the dry state; conditioned values are commonly 15–20% lower. Tensile strength at break follows a similar trend, but elongation at break declines below 5%, which means this grade is not selected for energy-absorbing snap-fits or high-deflection spring elements. Compared with EMS-Grivory PA12-GF30 and PA12-GF50 materials, the 65% glass compound provides higher stiffness and lower mould shrinkage, but it also generates greater wear on mould gates, ejector pins, and screw tips. The high filler content reduces weld-line strength because glass fibres do not bridge the knit line; multi-gate tooling therefore demands more conservative design factors than unfilled or lightly filled PA12.

The lower moisture uptake of PA12 is a decisive difference from PA66. At saturation in water at 23 °C, unfilled PA12 absorbs approximately 1.5% water by mass, while unfilled PA66 absorbs roughly 7–8% under comparable ISO 62 immersion conditions. In a 65% glass-filled compound, the absolute moisture uptake is lower still because the filler does not absorb water. This gives PA12-GF65 components dimensionally stable operation in humid air and occasional exposure to cold water; however, immersion in hot water above 80 °C under mechanical load can still promote hydrolysis over extended service life. The material is therefore not a direct substitute for PPA or PPS in continuous hot-water or steam environments.

Conditioning protocol alters the ISO 527 tensile response

The term “conditioned” for EMS-Grivory Grilamid LV-65H SST nat refers to a defined moisture condition, not a coating or surface treatment. ISO 1110 accelerated conditioning at 70 °C and 62% relative humidity brings the specimen to an equilibrium moisture content representative of ambient exposure. The absorbed water plasticizes the polyamide matrix, reducing hydrogen bonding and lowering the glass transition temperature of the matrix phase. In the 65% glass-reinforced compound, this produces a drop in tensile modulus of approximately 15–20% relative to the dry-as-moulded condition; elongation at break increases from roughly 2.5% to 4%, while notched Charpy impact strength at 23 °C typically increases by 10–20% according to ISO 179/1eA. Design stress values should therefore use the conditioned data when the part will reach ambient moisture equilibrium in service, while dry values are relevant for short-term structural loads immediately after moulding or for parts continuously exposed to dry heat.

Thermal expansion is anisotropic in this filler-loading range. Between -30 °C and 30 °C, the coefficient of linear thermal expansion in the flow direction is approximately 0.2 × 10⁻⁴ K⁻¹, while cross-flow values can be 0.5–0.7 × 10⁻⁴ K⁻¹ according to ISO 11359-2. This anisotropy must be used in finite-element modelling of large housings; isotropic material data underestimates corner stress and thermal stress at mechanical fixings.

When pre-drying and barrel temperature profiling become the processing constraint

Moisture content above 0.1% at the feed throat can hydrolyze the polyamide in the melt phase, leading to a reduction in molecular weight and a loss of notched impact strength by 20–30% in the worst case. The defect appears in natural parts as surface splay, silver streaks near the gate, and reduced Charpy values at the knit-line. Barrel profiles for PA12-GF65 typically start at 230 °C in the rear zone and rise to 260–280 °C in the mid and front zones; the nozzle temperature should be held near 250 °C. Screw back pressure should be kept below 5 MPa to limit glass fibre breakage. Screw speed should remain below 0.3 m/s peripheral velocity on 25–35 mm diameter screws because the glass fibres are abrasive and the high filler content increases shear heating. On twin-screw compounding lines with L/D 40, the glass is side-fed downstream to preserve fibre length and to limit excessive shear on the PA12 melt.

For thin-walled parts below 1.0 mm section, the high glass content restricts flow length and may require gate diameters above 1.2 mm. In an actual production trial on a 150-tonne electric injection moulding machine producing a 2.5 mm nominal wall housing, the flow length in a spiral mould at 260 °C melt temperature and 100 °C mould temperature was substantially shorter than a 30% glass-filled PA12 grade. Comparative flow-length data are generally obtained from mould-filling simulation or spiral-flow tests conducted at the tool trial stage, and published data for this specific configuration is limited.

Injection moulding fibre orientation, weld-line strength, and dimensional stability

At 65% glass fibre loading, fibre orientation is the primary driver of mechanical anisotropy. In a single-gated tensile plaque moulded to ISO 294-4, the flow-direction tensile modulus can be 20–30% higher than the transverse direction. Weld lines formed by two melt fronts exhibit tensile strengths of 40–60% of nominal strength because the perpendicular fibres do not bridge the knit line. Gate placement must therefore direct weld lines away from tensile stress concentrations and pressure-bearing features. Mould-filling simulation programs that include fibre orientation tensor prediction are used to compare gate positions before steel cutting, especially for natural grade parts where visually apparent glass orientation can create local gloss variation. Shrinkage anisotropy in 60 mm × 60 mm × 2 mm plaques is characterized by flow-direction shrinkage below 0.1% and transverse shrinkage from 0.3% to 0.5%. That difference must be accommodated in tool dimensions; steel adjustments on prototype tools are often required when moving from a PA12-GF30 to this 65% glass-filled grade.

After moulding, the natural part absorbs moisture from ambient air. A 100 mm dimension can expand by 0.1–0.2% between the dry-as-moulded and conditioned states; that is smaller than the 0.5–1.0% dimensional growth commonly observed in PA66-GF60 under the same environmental change. This lower expansion makes the grade suitable for structural housings in climates with seasonal humidity variation, provided the design tolerance is not below the absolute dimensional change. Post-moulding machining of PA12-GF65 requires carbide or diamond-coated tools; the glass fibres abrade high-speed steel rapidly. Cutting speeds below 120 m/min and feed rates of 0.1–0.3 mm/rev reduce exit-side delamination during milling or drilling. Ultrasonic welding and laser marking are possible, but weld energy director heights and laser parameters require adjustment because the high filler content prevents the matrix from forming a uniform neat-polymer surface.

What regulatory and safety status is documented for this glass-filled PA12?

The material is normally included in supplier declarations for RoHS Directive 2011/65/EU and REACH Regulation (EC) No 1907/2006. The natural grade contains no intentionally added colourants, but pigment and additive lot-specific information must be confirmed from the EMS-Grivory datasheet and safety data sheet. A compliance checklist is used in production-part approval processes such as PPAP; the table below summarizes the typical documentation basis but does not replace a current supplier certificate.

The grade also requires validation for medical device applications. Biocompatibility under ISO 10993-1 is not implied by the polymer chemistry alone; additive packages, glass sizing, and process residues must be evaluated on finished components. Electrical properties such as comparative tracking index per IEC 60112 and dielectric strength per IEC 60243-1 require moulded plaques with the target fibre orientation; the high glass content reduces surface homogeneity and can lower dielectric strength relative to unfilled PA12. For applications exposed to fuels, oils, or road salt, PA12 is generally resistant to aliphatic hydrocarbons, mineral oils, grease, and neutral salt solutions, but continuous contact with strong acids, phenols, and concentrated formic acid can degrade the matrix; compatibility testing per ISO 175 or SAE J1744 should be conducted on finished parts with moulded-in stress.

In traction-control sensor housings, brake-line clips, and industrial valve bodies, the material is selected for low moisture expansion and high compression strength. The high glass content increases creep resistance under short-term clamping loads; supplier-generated creep curves under ISO 899-1 are used to calculate allowable stress at 23 °C and 80 °C. However, the PA12 matrix imposes a continuous service temperature limitation, commonly below 120 °C under mechanical load. In thermally demanding underhood locations with continuous temperatures above 150 °C, PPA or PPS grades are preferred, while in deep cryogenic service the impact toughness of PA12 may be beneficial but must be tested at the target temperature because glass-filled thermoplastics become increasingly brittle below -40 °C.