EMS-Grivory Grilamid XE 3982 is a 30 % glass-fibre-reinforced polyamide 12 injection-moulding compound supplied as pellets for conventional reciprocating-screw melt processing. The material belongs to the PA12-GF30 family under ISO 1874-1, and the glass content is verified by ash analysis following ISO 3451-1. Under ISO 1183-1, the dry-as-moulded density is typically 1.22 g/cm³ to 1.24 g/cm³; the variation is attributable to pigment addition and fibre-content lot tolerance. Under ISO 527-1/-2 at 23 °C, the dry tensile modulus is reported between 2800 MPa and 3200 MPa, while the conditioned value at 50 % relative humidity is reported near 2100 MPa. The material is semicrystalline, and mould shrinkage measured on 60 mm × 60 mm × 2 mm plaques according to ISO 294-4 is typically 0.10 % to 0.30 % parallel to flow and 0.40 % to 0.70 % perpendicular to flow. Because the glass fibres orient preferentially in the fill direction, these values are not isotropic, and cavity dimensions must compensate for differential shrinkage. The compound is specified for pressure-bearing fluid connectors, pneumatic distributor blocks, medical device housings, and industrial quick-connect couplings where PA12 low moisture uptake and chemical resistance are required.

The grade should not be treated as a direct drop-in for unfilled PA12 or for PA6-GF30 in existing tools. The glass-fibre orientation creates anisotropic mechanical response, and the melt viscosity is higher than that of unfilled PA12 at the same temperature. Tooling changes are normally required to reposition gates away from weld-line-sensitive seal bosses, to increase runner diameters, and to adjust hold-pressure profiles so that the lower thermal conductivity of the glass-filled melt does not produce premature gate freeze. Batch-to-batch variation in fibre length distribution and pigment dispersion is controlled by the producer, but regrind levels above 20 % by mass can shift Charpy notched impact strength and should be validated on the production press.

What Separates Grilamid XE 3982 from Unfilled PA12 in Humid Service?

The primary difference is the 30 % glass-fibre mass fraction, which increases the dry tensile modulus by a factor of approximately 2.5 to 3 relative to unfilled PA12 while reducing the coefficient of linear thermal expansion from roughly 110 × 10⁻⁶ K⁻¹ to 150 × 10⁻⁶ K⁻¹ to 25 × 10⁻⁶ K⁻¹ to 40 × 10⁻⁶ K⁻¹ along the flow direction when tested under ISO 11359-2. The penalty is reduced elongation at break: dry unfilled PA12 typically exceeds 50 % under ISO 527-1/-2, whereas the glass-filled grade falls below 4 % in the dry state. In humid service, the PA12 matrix absorbs less water than PA6 or PA66; reported equilibrium moisture at 23 °C and 50 % relative humidity is approximately 1.5 % for unfilled PA12 and 0.7 % to 0.9 % for the 30 % glass-filled compound under ISO 62. The conditioned modulus therefore remains higher than that of conditioned PA12-GF15 and approaches the dry values of some lower-fibre PA12 grades.

Where unfilled PA12 is selected for impact resistance, Grilamid XE 3982 is selected only when the service load direction is predictable and the stress concentration at moulded-in holes or weld lines is controlled. The glass-fibre orientation produces anisotropic tensile strength; flow-direction strength is typically 10 % to 15 % higher than transverse strength in flat plaques, so gate location must place weld lines away from pressure boundaries. Chemical resistance to aliphatic hydrocarbons, mineral oil, and zinc chloride salt solutions remains close to unfilled PA12, but stress-crack resistance is lower when fibre ends act as local stress raisers under tensile load. Components exposed to zinc chloride road-salt solutions should be validated under ISO 22088-2 because geometry, fibre orientation, and moulded-in strain control the time to crack initiation.

In pneumatic and hydraulic actuator components, the grade is processed on machines with clamp force capacities from 800 kN to 2500 kN; the moulded parts are typically pressure-tested after conditioning to ISO 3601 or customer-specific leak specifications. Hot-runner systems require externally heated manifolds with minimal dead spots because glass-filled PA12 exhibits a residence-time-dependent viscosity increase when held at melt temperature above 250 °C for longer than 10 min. On a 40 mm screw with L/D 24, barrel temperatures are set in a reverse profile from 240 °C at the nozzle to 220 °C in the rear zone, while the mould temperature is held between 50 °C and 80 °C to accelerate crystallisation and reduce post-moulding warpage. Screw rotation should be controlled to limit fibre attrition; high back pressure above 80 bar can reduce fibre length and decrease notched impact strength below the lower end of the supplier-published range.

Injection Moulding Melt-Temperature, Drying, and Residence-Time Limits

Pre-drying is mandatory after opened or non-dried storage. A desiccant dryer with dew point of −35 °C or lower and air-flow capacity of 3.7 m³/h per 100 kg of resin is used to dry the pellets at 80 °C for 4 h to 6 h until residual moisture is below 0.10 %. Hopper residence time should not exceed 30 min at 80 °C if the hopper is unsealed, because moisture regain can occur in plant air at 60 % relative humidity. The melt temperature measured by air shot should remain within 230 °C to 250 °C; exceeding 260 °C causes accelerated chain scission, visible yellowing, and a drop in notched Charpy impact strength of 20 % to 30 % after 15 min of residence. A screw with compression ratio of 2.0:1 to 2.5:1 and a non-return valve with free-flow clearances of 1.0 mm to 1.5 mm is recommended to limit fibre attrition.

Short shots and jetting are more likely in this grade than in unfilled PA12 because the glass-filled compound exhibits higher heat capacity and reduced flow length under the same injection pressure. The mould should be vented at the last-fill locations with vent depths of 0.01 mm to 0.02 mm to prevent gas burn at the flow front. Hold pressure should be raised progressively until the part mass stabilises; pressure loss in the cavity is anisotropic and maximum hold pressure is commonly set at 50 % to 70 % of the available machine pressure. Parts moulded with insufficient hold time show sink marks around bosses and a 0.05 % to 0.15 % increase in flow-direction shrinkage relative to the datasheet value.

Thermomechanical and Rheological Data Boundaries

The following table summarises typical dry-as-moulded and conditioned values reported for PA12-GF30 compounds of this class under the cited test methods. Values are not specification limits and should be confirmed against the current supplier certificate of analysis.

The measured melt viscosity is shear-thinning; the flow behaviour observed on a capillary rheometer indicates that apparent viscosity at 1000 s⁻¹ falls within 120 Pa·s to 180 Pa·s at 240 °C for the dry compound. In injection moulding, this shear-thinning characteristic allows filling of thin walls down to 1.0 mm when the gate is located in the thickest section and the flow path is not interrupted by sharp transitions. Nevertheless, weld-line strength in thin walls is typically 30 % to 40 % lower than the bulk tensile strength, and design verification should include tensile testing of weld-line specimens cut transverse to the flow path.

Moisture conditioning shifts the glass transition and reduces the modulus because water acts as a plasticiser in the PA12 matrix. This does not represent chemical degradation; drying restores most of the dry modulus unless hydrolytic chain scission has occurred at elevated temperature. For dimensional stability under fluctuating humidity, the glass fibres dominate the thermal expansion response, but the matrix swelling coefficient still contributes to a smaller hygroscopic expansion than PA6-GF30. Comparative tests under ISO 62 show that PA12-GF30 absorbs roughly one-half to two-thirds of the water mass absorbed by PA6-GF30 at equilibrium in 50 % relative humidity.

When Continuous Aqueous Exposure Exceeds 70 °C

PA12 has lower hydrolytic degradation rate than PA6 or PA66, but the operational boundary is not unlimited. In continuously circulating hot-water systems above 70 °C, the amorphous fraction of the matrix is susceptible to hydrolytic chain scission, and the fibre-matrix interface can degrade by water ingress. Published data for this specific configuration is limited; accelerated ageing under ISO 175 in water at 80 °C should be used to generate Arrhenius-based service-life predictions for a particular stress level. The compound should not be specified for continuous service in wet steam lines or pressurised hot-water loops above 80 °C without long-term creep rupture testing under ISO 899-1 and ISO 175.

For short-term sterilisation protocols, such as steam autoclave cycles at 121 °C for 15 min to 30 min, the material can be evaluated on the finished part. Repeated autoclave exposure reduces notched impact strength faster than flexural modulus; after 100 cycles, Charpy notched impact may fall by 15 % to 25 % depending on part thickness and gate-induced orientation. If the application requires repeated autoclave treatment, the design should use generous radii, avoid sharp corners at inserts, and eliminate weld lines crossing the pressure boundary. Annealing at 80 °C for 2 h before first use can reduce internal stress and improve dimensional stability, but it does not eliminate the long-term hydrolysis risk in continuous hot-water service.

Dimensional Verification of Moulded Parts Under ISO 294-4

Dimensional control of Grilamid XE 3982 requires conditioning before measurement. The dry-as-moulded part continues to absorb moisture from ambient air, and dimensions change by approximately 0.05 % to 0.15 % between 24 h and 96 h after ejection when stored at 23 °C and 50 % relative humidity. ISO 294-4 defines the cavity-pressure and hold-pressure conditions for reproducible plaque moulding, but production parts with variable wall thickness do not follow plaque shrinkage values exactly. Metrology should be performed after conditioning to ISO 291 for at least 48 h, and critical dimensions should be referenced to a fixed datum plane to avoid error from part warpage.

Compared with PA6-GF30, PA12-GF30 shows lower moisture-induced dimensional change, but its heat deflection temperature under load is lower. Compared with PBT-GF30, PA12-GF30 offers lower density and higher impact resistance, but PBT-GF30 may provide better dimensional stability at elevated temperature and lower water absorption. Compared with PA66-GF30, PA12-GF30 provides better resistance to zinc chloride stress cracking and lower equilibrium moisture uptake, while PA66-GF30 retains higher heat deflection temperature. These differences mean substitution decisions should be based on the full set of environmental, chemical, and mechanical load cases rather than a single property.

In medical device housings and fluid connectors, validation under ISO 10993-1 is performed on the final moulded part, not on the raw pellet; extractables and leachables can shift with regrind level, colourant package, and mould-release residues. The material absorbs less water than PA6-GF30 and therefore shows smaller dimensional change after 48 h of aqueous exposure at 37 °C; however, published data for this specific configuration is limited, and lot-specific testing is required for patient-contact devices under ISO 10993-5 and ISO 10993-10. Regulatory documentation should include the supplier declaration for REACH SVHC content and RoHS Directive 2011/65/EU Annex II compliance, with the specific colour batch identified on the certificate of analysis.