EMS-Grivory Grilamid L 25 W 20 Nylon 12, Dry is a plasticizer-modified polyamide 12 homopolymer supplied as moisture-controlled granules. The L prefix identifies the PA12 base chemistry in the EMS-Grivory material nomenclature; the W 20 suffix corresponds to a softened/plasticized modification, and the Dry designation indicates a controlled as-supplied moisture level rather than an unconditioned melt state. The PA12 backbone is synthesised from laurolactam or ω-aminolauric acid and carries an aliphatic segment of approximately 11 methylene groups between amide linkages. That structural feature lowers amide-group density relative to PA6 and PA66, reducing equilibrium moisture uptake to a typical range of 1.4 % to 1.6 % by mass for the unmodified base polymer under ISO 62 immersion. The plasticizer package modifies absolute mechanical values, so grade-specific data from the EMS technical datasheet must control final design calculations.

The dry supply condition is specified because PA12 is hygroscopic enough to require moisture control before melt processing. In sealed packaging, the residual moisture content is usually maintained below 0.10 % by mass. Once the package is opened at relative humidity above 60 % RH, the granules begin to reload moisture. Before extrusion or injection moulding, moisture should be reduced to 0.10 % or less; a desiccant dryer with a dew point of −30 °C or lower and an air temperature of 80 °C to 100 °C is used for 4 h to 8 h. Hot-air drying may be acceptable only in low-humidity plants when the granule bed depth does not exceed 50 mm and the hopper is covered.

Application context from EMS-Grivory technical literature includes flexible tubing, cable sheathing, pneumatic lines, and injection-moulded fasteners. The grade is typically selected for applications requiring low moisture uptake, lower density, and retention of ductility after conditioning; chemical exposure must be validated according to application-specific standards such as ISO 175 or automotive fuel-resistance test methods. The material is not a direct replacement for short-chain polyamides in load-bearing structural components unless the lower tensile modulus and plasticizer-modified strength values are explicitly included in the part calculation.

How Does Low Amide Density Affect Property Retention in Wet Environments?

Water absorption in polyamides is governed mainly by hydrogen bonding at amide sites. Because PA12 contains fewer amide groups per unit chain length than PA6 or PA66, its saturated moisture content under ISO 62 is approximately 1.4 % to 1.6 %, whereas PA6 typically absorbs 9 % to 10 % and PA66 approximately 8 % to 9 % by mass. The lower moisture loading produces a smaller shift in tensile modulus from the dry-as-moulded condition to the conditioned state. For PA6 and PA66, tensile modulus according to ISO 527-1:2019 can fall from roughly 3,000 MPa dry to below 1,500 MPa after conditioning at 50 % RH; the PA12 class moves through a narrower band. For a plasticized grade such as L 25 W 20, the absolute modulus is lower, but the moisture-induced shift remains smaller than for short-chain polyamides.

The practical result is more predictable dimensional integration in humid service. Tubing, clips, and cable jackets made from PA12-based material exhibit lower longitudinal growth and less stiffness loss after water exposure. That does not eliminate the need for conditioning-sensitive tolerance studies on the final extruded profile; radial wall-thickness changes and residual stress relaxation still require validation under the end-use humidity and temperature cycle.

Comparative Property Benchmarks Against PA6, PA66, and PA11

A direct comparison of polymer-class reference values shows why the material is specified for moisture-sensitive and low-density applications. The table below uses dry-state values for the unmodified base polymers; the exact W 20 grade data must be obtained from the EMS-Grivory datasheet because plasticizer content shifts mechanical and rheological values.

Those values explain the selection logic. Grilamid L 25 W 20 is preferred over PA6 or PA66 when the application must maintain ductility after humid ageing and when part mass and moisture-induced dimensional movement are constrained. It is preferred over PA11 when the PA12 chemical resistance profile, lower density, or specific extrusion rheology is required; PA11 may be selected when a partly bio-based feedstock is a decisive requirement. The comparison against unmodified PA12 is equally important: the W 20 plasticizer modification trades off tensile modulus and hardness for higher elongation, lower flexural stiffness, and improved low-temperature impact behaviour. Published data for the exact plasticizer content and the resulting notched Charpy values under ISO 179-1:2010 should be consulted; generic PA12 class values cannot be substituted for design checks.

For applications involving fuel or oil contact, PA12-based grades are usually evaluated by volume and mass change after immersion under ISO 175 or by retention of tensile properties after fuel exposure under automotive standards. The lower amide density gives polyamide 12 a different polarity balance than PA6 or PA66, which can reduce the driving force for polar-fluid absorption. However, the plasticizer package in the W 20 grade may be partially extractable in some fluid formulations, so compatibility testing must be performed on the finished extruded tube or injection-moulded component with the actual service fluid. Published data for this specific configuration is limited when aggressive blends containing biodiesel or ethanol are involved.

On production-scale single-screw extruders with L/D ratios of 30:1 to 36:1 and compression ratios of 2.5:1 to 3.0:1, the melt temperature for Grilamid L 25 W 20 is normally controlled between 210 °C and 240 °C. Barrel profiles are ramped in three or four zones from a feed zone at 180 °C to 200 °C, through compression at 220 °C to 240 °C, to metering at 230 °C to 250 °C. Melt temperatures above 270 °C increase the risk of thermo-oxidative chain scission, yellowing, and loss of melt strength; total barrel residence time should be kept below 15 min. In injection moulding, barrel temperatures of 220 °C to 260 °C and mould temperatures of 40 °C to 80 °C are typical for PA12-based grades. Lower mould temperatures may be used for fast cycle times, but they can increase the frozen-in stress level and reduce the ductility of thin-wall sections.

Screw design for extrusion should use a three-zone screw with a mixing section when colourants or stabiliser masterbatches are added. For tubing and cable sheathing, filtration through a breaker plate with screen packs of 60/80/100 mesh is common; the pressure must be monitored to avoid exceeding the barrel flange and gearbox rating. Melt pressure on a 45 mm single-screw line at moderate throughput typically remains in the 150 bar to 250 bar range for PA12-based tubing compounds, but this range is not a product specification and must be verified on the actual line. Because PA12 has a coefficient of linear thermal expansion of approximately 110 × 10⁻⁶ K⁻¹ to 130 × 10⁻⁶ K⁻¹ under ISO 11359-2, tooling dimensions for injection moulds and calibration sleeves must allow for greater shrinkage than PA6 or PA66.

The process control envelope for the dry material is summarised below. The values are not grade-specific moulding recipes but are the control limits used in production planning; actual settings must be established on the production machine and recorded in the process sheet.

At the upper end of the melt-temperature range, residence time becomes the controlling variable. On a 30 mm laboratory extruder, short hold-up times may permit 250 °C without visible degradation, whereas a large accumulator head on a production line can hold material for longer than 10 min and should operate at the lower end of the temperature envelope. The difference is not a material inconsistency but the expected behaviour of a polyamide with a melt viscosity that depends on both thermal history and shear history.

Under ISO 1133-1:2022, the melt volume-flow rate of plasticized PA12 grades is higher than that of unmodified PA12 base polymer at the same load because the plasticizer reduces chain friction and free volume. The exact MVR value for L 25 W 20 should be taken from the supplier’s certificate of analysis, but the increased flowability permits thin-wall injection filling and high-speed extrusion of small-diameter tubing. However, the same flowability narrows the processing window for vertical walls: excessive melt temperature or excessively long residence time can produce flow marks, jetting, and dimensional instability in moulded parts.

When the Dry Condition Is Lost, Corrective Drying Must Precede Processing

If the sealed package is opened or damaged, moisture uptake begins immediately at a rate that depends on ambient relative humidity, temperature, and granule surface area. At 23 °C and 80 % RH, open-stored pellets can reach process-relevant moisture levels within several hours. Processing wet PA12 produces splay marks, surface roughness, and hydrolysis-induced viscosity loss; at die temperatures above 240 °C, dissolved water accelerates chain scission and can reduce extrudate burst strength. The corrective action is not to increase barrel temperature, because this worsens hydrolysis and thermal degradation. The material should be redried in a desiccant dryer at 80 °C to 100 °C for 4 h to 8 h. The drying air should have a dew point of −30 °C or lower and the moisture content should be confirmed at 0.10 % or less using ISO 15512:2019 or an equivalent calibrated Karl Fischer method. If the material has been stored in an open silo for more than 24 h, drying time may need to be extended to 8 h to 12 h; this is not a universal correction because hopper geometry, airflow distribution, and ambient load vary between plants.

The Dry Supply State Requires Controlled Storage and Handling

Sealed packaging of the dry grade should be stored at temperatures between 10 °C and 30 °C and protected from direct sunlight and precipitation. Under those conditions, the manufacturer’s unopened shelf life is normally stated on the lot certificate; a period of at least 24 months is common for PA12 compounds, but the lot-specific document controls the actual limit. Opened bags should be reclosed immediately after transfer and purged with dry nitrogen when the remaining material will be stored longer than one shift. Storage should avoid direct contact with concrete floors because migration of alkaline ground moisture can contaminate the granulate surface, and strong oxidising agents or solvent vapours should not be stored in the same cabinet.

Chemical incompatibilities include hot concentrated mineral acids, phenols, cresols, and concentrated formic acid, which dissolve or severely degrade PA12. Chlorinated solvents may induce environmental stress cracking in moulded parts with high residual stress. Continuous exposure to hot water above 90 °C requires long-term hydrolysis, creep, and extraction data on the actual part geometry because plasticizer migration can alter flexibility and surface properties over time. Food-contact, potable-water, medical, and flame-retardant compliance is not automatically conferred by the PA12 polymer family; the specific EMS-Grivory commercial item, colour, and lot-specific regulatory documentation must be checked before such use.