Evonik Vestamid X7293 is a plasticized nylon 12 (PA12) extrusion and injection moulding compound supplied by Evonik Operations GmbH. The formulation combines a semicrystalline PA12 backbone with an external plasticizer package, producing a Shore D hardness below that of an unmodified PA12 homopolymer while retaining the comparatively low saturated water uptake and aliphatic hydrocarbon resistance of long-chain polyamide chemistry. A supplier datasheet value for density is 1.02 g/cm³ when determined according to ISO 1183-1. The product is therefore within the expected density envelope for PA12 and lighter than many flexible copolyester elastomers of equivalent flexibility.

The material is typically converted into pneumatic tubing, cable sheathing, and flexible line sets for automotive and industrial installations. In these applications, the combination of fuel-vapour resistance, low moisture regain, and low-temperature impact strength is more important than short-term tensile stiffness. Production experience on single-screw tube lines indicates that the grade feeds uniformly in grooved-barrel machines when the feed throat is cooled to 40–60 °C and when upstream regrind is dried to the same moisture specification as virgin pellets. Where end-use specifications require burst strength, wall thickness control is influenced primarily by melt stability and die pressure, not by the material's Shore D value in isolation.

Under the nomenclature of ISO 16396-1, the product belongs to the general polyamide 12 moulding and extrusion category; however, the grade-specific designation block and the coding associated with plasticizer type should be confirmed on the current Evonik technical datasheet, because externally plasticized compounds may appear in different regional supply forms with identical trade names.

What Limits Moisture Uptake and Residence Time in Melt Processing?

Residual moisture is the principal process variable. Polyamide 12 hydrolyzes during melt conversion when water content is excessive, but its saturated water absorption is much lower than that of PA6 or PA66. For Evonik Vestamid X7293, pre-drying at 80 °C for 4–8 h in a desiccant dryer with a dew point no higher than -30 °C is the standard recommendation to bring moisture below 0.1% as determined by ISO 15512. Moisture above 0.15% can produce surface roughness, die-lip deposit accumulation, and loss of melt strength during tubing extrusion. The drying hopper should be sized for the throughput of the line; for example, a line producing 100 kg/h requires a hopper residence time that is at least the specified drying time, not merely the material temperature.

Melt temperature for extruder operation is generally maintained between 210 °C and 250 °C, with barrel zones in the range 220–240 °C and the die adaptor close to 230 °C. The upper processing threshold should be 260 °C; above this temperature, plasticizer degradation and polyamide chain branching become measurable as a shift in melt viscosity and the formation of gel particles. Residence time at melt temperature should be limited to 15 min or less. In practice, a single-screw extruder with L/D 25–30, a compression ratio of 2.5:1–3.0:1, and a barrier or three-zone screw provides sufficient plasticizing without excessive shear. Screen packs of 60/80/100 mesh are used to trap gel particles, but the melt filtration area must be large enough to prevent pressure fluctuations above ±5% of the die pressure setpoint.

Vacuum venting is not usually employed unless low-molecular-weight volatiles from heavily pigmented regrind are present. Aggressive devolatilizing vacuum can strip external plasticizer from the melt surface and reduce retention of elongation at break. When a vent is used, the barrel upstream of the vent should be sealed and the vacuum stage should be operated only to the minimum absolute pressure required to remove visible splay, rather than at the maximum pump capacity. Published process data for deep-vacuum degassing of this specific grade is limited; qualification runs should include retained elongation testing according to ISO 527-1/-2 on extruded tube samples.

When injection moulding fittings, melt temperature should remain in the same 210–250 °C range and mould surface temperature at 40–60 °C. Back pressure below 10 bar is preferred to avoid excessive shear heating and surface blush. Clamp force requirements are moderate; the compound has flow characteristics similar to other semi-rigid PA12 grades, but the lower viscosity may allow shorter hold-pressure time in thin-wall sections. Gate freeze-off time should be established by seal pressure trials, not by copying unplasticized PA12 conditions.

The dry-as-moulded mechanical profile of Evonik Vestamid X7293 places it between a rigid unplasticized PA12 and a soft polyether block amide. Under ISO 527-1/-2, published representative values for tensile modulus are approximately 300–450 MPa, while unplasticized PA12 homopolymer grades commonly exceed 1,200 MPa. Shore D hardness under ISO 868 is typically reported in the range 55–65, compared with values above 70 for rigid PA12. Elongation at break is typically greater than 200%. The Vicat B50 softening point measured under ISO 306 is generally reported near 135–150 °C, which is below that of unplasticized PA12 and must be considered for hot-air or under-hood retention clips.

These values are supplier representative values for dry-as-moulded test specimens; they are not specification limits and do not substitute for lot-specific certificate of analysis data. Test specimens conditioned at 23 °C and 50% RH according to ISO 291 may show slightly lower modulus than dry-as-moulded values because absorbed moisture acts as a mild plasticizer.

Low-temperature impact response is one of the main reasons for selecting this plasticized PA12 instead of a rigid PA12. Charpy notched impact values under ISO 179-1/1eA at -40 °C are often reported as no break for plasticized PA12; however, lot-specific testing is required because these results depend on moisture conditioning, notch radius, and specimen thickness. The material is therefore specified for tubing that must survive cold-coiling and impact installation in winter assembly conditions, but a no-break result from a datasheet should not be extrapolated to a finished multi-layer tube without component burst and cold-impact testing.

Comparative Position Against Unplasticized PA12 and Polyether Block Amide

Relative to an unplasticized PA12 grade, Evonik Vestamid X7293 displays lower room-temperature stiffness, lower Vicat softening, and improved flexibility at low installation temperatures. The plasticizer shifts the tensile modulus downward by roughly two-thirds or more; however, the material retains the melt temperature and density of the PA12 main chain rather than forming an entirely new polymer class. This distinguishes it from copolyamide or polyether block amide elastomers, where the soft phase is built into the polymer backbone and no external plasticizer is required.

Differential scanning calorimetry under ISO 11357-1/-3 shows a melting endotherm at roughly 170–178 °C, which is comparable to general PA12. The plasticizer primarily affects the amorphous fraction; it reduces the upper glass transition and increases molecular mobility, but it does not eliminate the crystalline melting point. Consequently, the material retains a distinct melting process rather than displaying the broad elastomer transition characteristic of a crosslinked rubber or a high-soft-phase copolyamide.

Water uptake at saturation under ISO 62 is approximately 1.0% for PA12, whereas short-chain PA6 reaches saturation values near 9–10%. This difference means that dimensional change and loss of yield strength in humid air are smaller for Evonik Vestamid X7293 than for plasticized PA6 compounds. In return, external plasticizer migration can occur in contact with hot oils, hydrocarbon fuels, or strong oxygenated solvents, and this mechanism is not observed to the same extent in polyether block amides because the soft segment is covalently bound.

The product therefore should not be selected as a direct drop-in replacement for polyether block amide in applications involving continuous extraction by aggressive fluids. Conversely, polyether block amide may exhibit lower modulus below Shore D 40, while Evonik Vestamid X7293 remains in the semirigid flexibility band and retains PA12 fuel-vapour resistance.

When Long-Term Hydrocarbon Exposure Dictates Material Selection

If the intended application involves continuous contact with diesel, gasoline, or lubricating oil at elevated temperature, qualification should include immersion testing under ISO 175 with the actual fluid and temperature cycle, followed by tensile property retention according to ISO 527-1/-2. PA12 is inherently resistant to aliphatic hydrocarbons, but externally plasticized formulations can lose flexibility through plasticizer extraction; the retained elongation at break and hardness change after immersion are more informative than visual swelling alone.

In atmospheric fuel-vapour exposure typical of pneumatic line sets, the low polarity and aliphatic character of PA12 limit swelling, but liquid-phase hot oil immersion above 80 °C should be evaluated in the specific fluid because antioxidant and plasticizer partitioning can shift the ductility profile. Publication-grade extraction coefficients for this specific grade are limited in open literature; therefore, end-use qualification should be empirical rather than predicted from generic PA12 diffusion data.

Chemically, strong mineral acids, phenols, and certain zinc chloride-containing solutions are known to attack PA12. Avoid exposure to these media in any application where stress cracks or surface recession cannot be tolerated. For applications requiring compliance with automotive tubing standards, the component must be tested to the applicable end-use document, such as SAE J844 or ISO 7628, rather than being approved solely on the basis of the base resin datasheet.