| HS Code | 194863 |
| Density | 1.01 g/cm³ |
| Melting Point | 178 °C |
| Glass Transition Temperature | 45 °C |
| Tensile Modulus | 1600 MPa |
| Yield Stress | 45 MPa |
| Elongation At Break | >200% |
| Charpy Impact Strength 23 C | No break |
| Shore Hardness D | 70 |
| Water Absorption 24h | 0.3% |
| Biocompatibility | ISO 10993 and USP Class VI |
| Sterilization Compatibility | Gamma radiation, ethylene oxide, steam |
As an accredited Evonik VESTAMID® Care ML24 Medical Grade Nylon 12 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | VESTAMID® Care ML24 medical-grade nylon 12 is supplied as pellets in sealed polyethylene bags inside fiber drums, typically 25 kg per container. |
| Container Loading (20′ FCL) | 20′ FCL loaded with palletized, sealed bags of VESTAMID® Care ML24, secured and ventilated to protect medical-grade nylon. |
| Shipping | VESTAMID® Care ML24 ships as resin pellets in sealed, moisture-proof bags or drums, protected from contamination and humidity. Keep dry, away from heat and direct sunlight. No hazardous goods classification under standard transport regulations. Ensure proper labeling for medical-grade material and maintain clean, dry conditions during transit. |
| Storage | Store VESTAMID® Care ML24 in its original, unopened packaging in a cool, dry, well-ventilated area. Keep away from direct sunlight, heat sources, and moisture. Ensure containers are tightly sealed after use to prevent water absorption, which can affect processing. Ideal storage temperature is below 30°C, with low humidity. |
| Shelf Life | Shelf life is typically 5 years when stored unopened, cool and dry, protected from moisture, light, and contamination. |
In thin-wall multi-lumen polyamide catheter shafts, VESTAMID® Care ML24 is processed as a predried, unfilled nylon 12 compound. Residual moisture is reduced to ≤ 0.10 wt% by desiccant drying at 80 °C for 4–8 h; moisture levels above 0.15 wt% produce splay, melt viscosity depression, and microvoiding in walls under 0.30 mm. A single-screw extruder with a barrier screw and 25:1 to 30:1 L/D ratio is typically configured with barrel zones from 180 °C to 240 °C, adapter at 235 °C, and a multipin die at 230–245 °C. Melt temperature measured at the discharge thermocouple is held below 250 °C; excursions above 260 °C for more than several minutes accelerate oxidative yellowing and molecular weight loss. Profiling is controlled with a vacuum sizer at -15 kPa to -30 kPa and a closed-loop laser gauge maintaining outer diameter within ±0.02 mm. Terminal devices include central venous catheter shafts and microcatheter bodies, where ISO 10555-1 applies to finished device performance. The specific die land length, draw-down ratio, and line speed are determined by lumen count; published data for this specific configuration is limited for ML24 in multi-lumen designs with wall thickness below 0.20 mm, so process capability studies must be performed against dimensional sampling plans rather than extrapolated from generic PA12 processing guides.
Hoop strength retention in braided polyamide shafts is governed less by the initial tensile properties of the jacket resin and more by interlayer stress distribution at the liner–jacket interface. When ML24 is used as an outer jacket over a lubricious fluoropolymer liner with a stainless-steel flat or round braid, the reflow step requires jacket melt temperature at the die of 220–235 °C and controlled cooling in a water trough at 25–40 °C; retarded cooling above the glass transition temperature allows excessive crystallinity that raises modulus but reduces interlayer ductility. After assembly, ethylene oxide sterilisation at 55 °C and repeated autoclave exposure at 121 °C cause moisture uptake below 1.0 wt%, but cyclic humidity can shift hoop strength by 5–10% relative to dry as-molded values when tested to ISO 11070 for introducer shafts. Processing boundaries include avoiding jacket melt pressure above 25 MPa in the overjacketing head because high shear at the braid interstices can displace fine braid wires and create thin-wall bands that fail first in torsion. Finished shafts are inspected for tensile force at break, tip deflection, and radiopaque stripe continuity. The VESTAMID® Care ML24 grade is supplied with ISO 10993-5 and ISO 10993-10 documentation; device-level validation under ISO 10993-1 remains mandatory because the braid and liner materials contribute extractables that alter the biological risk profile.
For balloon catheter preforms, the two-stage stretch blow molding sequence introduces orientation stresses that control double-wall wall thickness and rated burst pressure. An extruded ML24 parison with uniform wall thickness of 0.15–0.25 mm is first annealed at 60–80 °C in an inert oven, then transferred to a heated balloon mold maintained at 90–110 °C. Pre-stretch is applied along the longitudinal axis at a draw ratio between 2:1 and 4:1, followed by internal nitrogen pressure from 0.7 MPa to 1.5 MPa to force radial expansion against the mold wall. The final wall thickness after orientation typically falls in the 0.025–0.050 mm range, depending on balloon diameter and desired compliance. Residual moisture in the preform must remain below 0.08 wt%; otherwise steam pockets form during the high-temperature forming step, producing microvoids that reduce burst pressure under ISO 25539-1 device testing. The low equilibrium moisture uptake of PA12 relative to PA6 improves dimensional stability of the formed balloon during storage, but lot-specific orientation response should be verified via differential scanning calorimetry according to ISO 11357-3, with the melting peak near 176 °C. Balloon-forming operators should apply adiabatic cooling only after the mold has opened to avoid radial springback and folded pleat asymmetry. Published data for this specific configuration is limited for ML24 in sub-0.030 mm finished balloon walls, so bench burst and compliance data must be generated per catheter family.
Injection moulding of unfilled ML24 into Luer fittings, three-way stopcocks, and male/female adapters requires a clamp force of 45–80 tonnes for multi-cavity tools with eight to sixteen cavities, injection pressure between 800 bar and 1,200 bar, and melt temperature from 230 °C to 245 °C. Mold temperature is held at 40–80 °C using water or oil temperature control units; higher mold temperatures above 90 °C improve weld line strength in threads but extend cycle time and increase post-molding dimensional creep. The PA12 backbone provides dimensional accuracy under ISO 80369-7 because moisture equilibrium in use shifts dimensions less than in PA66, typically below 0.15% linear expansion from dry to 50% RH; dry-as-molded parts must still be conditioned at 23 °C and 50% RH for 48 h before final metrology to avoid false conformance. A compliance matrix is presented below to distinguish material-level data from finished-device obligations.
| Requirement | Standard / method | Scope and boundary |
|---|---|---|
| Cytotoxicity | ISO 10993-5 | Supplier lot documentation; extract preparation per ISO 10993-12 |
| Irritation and sensitisation | ISO 10993-10 | Material-level data; device-level testing required after molding and assembly |
| Systemic and intracutaneous reactivity | USP <88> Class VI | Applicable for patient-contact classification; cleaning and sterilisation can alter extractables |
| Small-bore connector misconnection resistance | ISO 80369-7 | Finished connector assembly, not raw resin specification |
| Tensile property verification | ISO 527-2 | Dry as-molded specimens; modulus band for PA12 typically 1,300–1,500 MPa at 23 °C |
| Moisture content after drying | ISO 15512 | ≤ 0.10 wt% before melt processing |
Resin feed to the injection unit should use a desiccant dryer with a dew point below -30 °C and a hopper throat seal to prevent ambient moisture re-uptake. Screw geometry with a low-shear, general-purpose compression ratio of 2.0:1 to 2.5:1 reduces shear heating and gate blush; valve gates on hot runner tips should be set with positive needle shutoff to avoid stringing. Terminal components include high-pressure stopcock bodies, urological drainage adapters, and enteral feeding connectors, each requiring ISO 13485 device assembly records and ISO 14971 risk management for misconnection hazards. Under repetitive steam sterilisation at 121 °C, dimensional change in PA12 luer threads is typically lower than in PA66 equivalents, but repeated cycles above 25 may still alter thread engagement torque; validation should include torque-to-engage after maximal clinical use cycles.
Cyclic compression of an extruded ML24 tube in a roller pump introduces a mixed fatigue mode: radial crush at the roller contact line, shear at the trailing occlusion zone, and flexural hinge stress at the tubing retainers. An unfilled PA12 tube with inner diameter 0.8–1.6 mm and wall thickness 0.4–0.8 mm is operated under a pump-head occlusion ratio between 0.20 and 0.35 of the unmounted inner diameter; higher occlusion raises output accuracy but shortens time to wall fracture. The material is dried to ≤ 0.10 wt% before extrusion and the tube is sized with a vacuum calibrator to a wall-thickness tolerance of ±0.03 mm. Flex fatigue data for PA12 in peristaltic applications are custom-device-specific rather than governed by a universal ISO or ASTM standard; published data for this specific configuration is limited for ML24, so accelerated roller-pump testing under ISO 10993-1 extraction conditions is used to establish lot stability. Terminal products include infusion pump segments in enteral feeding and surgical fluid management circuits. Because PA12 embrittlement under gamma sterilisation can occur at doses above 25 kGy, ethylene oxide sterilisation is preferred unless dose-controlled terminal gamma is validated by post-sterilisation tensile elongation loss below 10%.
When a catheter shaft requires radiographic visibility under fluoroscopy, barium sulfate or tungsten filler is compounded into the ML24 carrier at loading fractions from 20 wt% to 40 wt%. Above 20 wt%, the melt viscosity increases nonlinearly, the die swell decreases, and the surface gloss becomes matte; the extruder torque rises by 15–25% relative to unfilled resin in a single-screw compounder with 30:1 L/D and a vent port. A side-fed twin-screw masterbatch diluted with virgin ML24 at the molding or extrusion machine is preferred over direct dry blending because the filler must be fully wetted to avoid agglomerates that block catheter wall thin sections. Processing limits include a maximum melt temperature of 250 °C because the filler–polymer interface can catalyze oxidation; a vacuum level below -25 kPa at the vent prevents moisture-induced porosity. Terminal products include radiopaque tip markers, full-length radiopaque catheter shafts, and introducer sheaths. The final compound is not a simple mixture: the filler shifts the glass transition and may reduce tensile elongation at break by 20–40% when tested to ISO 527-2, so each new filler lot requires incoming verification of melt flow stability and dispersion using a 50-µm screen pack and an optical microscopy check at 100x magnification. Published data for this specific configuration is limited for ML24 at filler loadings beyond 40 wt%, because such heavily filled systems approach the percolation threshold for compression-set instability.
Laser transmission welding is applied to join a transmissive ML24 top housing to a black-absorbing PA12 base using a diode laser at 940 nm, with clamp force between 0.3 MPa and 0.8 MPa over the weld joint. The upper part is unpigmented ML24; the lower part contains a laser-absorbing carbon black masterbatch at less than 0.5 wt%. Weld depth is controlled by adjusting laser power from 20 W to 60 W and scan speed from 0.5 m/s to 2.0 m/s; improper thermal input creates either a weak bond or burn-out voids at the interface. Joint strength is verified by pressure-decay leak testing at 10 kPa and by burst testing of the assembled enclosure to 50 kPa, with the fused seam expected to fail cohesively rather than delaminate. Terminal products include reusable surgical handpiece housings and diagnostic instrument bodies, where the absence of ultrasonic weld flash eliminates a particulate contamination source in clean surgery. The material’s low equilibrium moisture uptake reduces dimensional change after steam sterilisation, but repeated autoclaving above 121 °C may accelerate surface hydrolysis at the weld line; therefore device validation under ISO 17665 requires cumulative cycle testing. All processing must occur under ISO 13485-controlled manufacturing conditions, and final biocompatibility must be re-evaluated because laser heating can generate low-level PA12 decomposition products at the weld interface; extractables testing per ISO 10993-12 is used to quantify this boundary.
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Evonik VESTAMID® Care ML24 is a semi-crystalline polyamide 12 (PA12) resin supplied in cylindrical pellet form for injection molding and melt extrusion. The grade is part of the VESTAMID Care portfolio, which is manufactured for medical device applications requiring documented change management, lot-to-lot consistency, and regulatory test data. According to the manufacturer’s technical documentation, the base resin is tested for cytotoxicity according to ISO 10993-5 and meets the requirements of USP Class VI in standard extraction studies. The material is not supplied sterile and is not a finished medical device; the device manufacturer retains responsibility for finished-device biocompatibility testing under ISO 10993-1 and for leachables assessment under ISO 10993-17 where applicable. The product is supplied in moisture-barrier packaging with batch-specific certificates of analysis. The manufacturer’s regulatory documentation for this grade references compliance with the applicable requirements of Regulation (EC) No 1907/2006 (REACH) and Directive 2011/65/EU (RoHS) as relevant to the supplied material.
The polyamide 12 chain has a lower amide group density than PA6 and PA66, which produces lower equilibrium water absorption and greater dimensional stability in humid environments. Moisture absorption at saturation for PA12 is approximately 1.5 % by ISO 62, whereas unmodified PA6 absorbs approximately 9.5 % and PA66 approximately 8.5 % under comparable conditions. This property is relevant in multi-lumen tubing, where differential expansion between walls and embedded elements can generate residual curvature after sterilization or storage. The semicrystalline morphology also provides resistance to softening at body temperature while retaining processability in conventional injection molding and extrusion equipment.
Representative physical and mechanical values obtained from conditioned specimens are listed in Table 1. These values are typical values, not specification limits, and may vary with processing history, pigmentation, or moisture content. For design decisions, conditioned values should be used rather than dry-as-molded values because polyamide properties shift with moisture uptake even at room temperature.
| Property | Test method | Typical value |
|---|---|---|
| Density at 23 °C | ISO 1183 | 1.01 g/cm³ |
| Melting temperature, DSC second heating | ISO 11357-3 | 176 °C |
| Vicat softening temperature, VST/B/50 | ISO 306 | 140 °C |
| Tensile modulus | ISO 527-1/-2 | 1500 MPa |
| Yield stress | ISO 527-1/-2 | 38 MPa |
| Nominal strain at break | ISO 527-1/-2 | >50 % |
| Moisture absorption at saturation, 23 °C | ISO 62 | 1.5 % |
| Shore hardness D | ISO 868 | 72 |
The crystalline melting temperature near 176 °C permits melt processing in standard water-heated barrel and mold systems. The Vicat softening temperature of 140 °C under 50 N load is a short-term heat resistance indicator, not a continuous-use temperature. The tensile modulus of 1500 MPa places ML24 above flexible polyether block amides and below rigid polyketones. At 23 °C and dry-as-molded conditions, the yield stress of 38 MPa supports load-bearing features such as snap-fit latches and threaded hubs, but design stress should be reduced when the part operates in aqueous environments. The nominal strain at break value above 50 % indicates that the material undergoes ductile yielding rather than brittle fracture at room temperature when loaded at moderate strain rates.
Table 2 lists the main test standards cited in the manufacturer’s regulatory documentation. The table does not replace finished-device validation; it identifies the standard methods used to generate the supplied data package.
| Requirement | Standard | Scope |
|---|---|---|
| Cytotoxicity | ISO 10993-5 | Base resin eluate testing |
| Acute systemic toxicity and intracutaneous reactivity | USP Class VI | Base resin extracts |
| Ethylene oxide residual testing | ISO 10993-7 | Finished device after sterilization |
| Radiation sterilization dose setting | ISO 11137 | Device bioburden-based dose |
| Moisture content | ISO 15512 | Pre-drying control |
Moisture control is the first processing constraint. Pellets exposed to ambient air at 23 °C and 50 % RH may exceed 0.2 % moisture within 24 h. Hydrolytic chain scission at melt temperatures above 220 °C then reduces molecular weight, increases melt-flow rate, and produces surface splay on molded components. A desiccant dryer with dew point below -30 °C and an inlet air temperature of 80 °C for 4 h to 8 h is required to reduce moisture to below 0.1 % as measured by ISO 15512 or Karl Fischer titration. Hopper residence time after drying should not exceed 30 min unless the hopper is purged with dry air or nitrogen.
The material should not be processed in equipment previously used for PVC compounds without a purging sequence because residual acidic chlorinated decomposition products can accelerate polyamide degradation. The supplier also recommends avoiding direct contact with strong acids, strong oxidizing agents, and chlorinated hydrocarbons at elevated temperatures. Published data for solvent exposure of ML24 is limited, and compatibility testing under ISO 10993-13 or device-specific conditions is required for finished components that contact such media.
In multi-cavity injection molding, the controlling variables are melt temperature, residence time, shear rate, and gate design. The recommended melt temperature range for ML24 is 220 °C to 250 °C. Barrel temperature profiles typically begin at 200 °C in the feed zone, rise to 230 °C to 240 °C in the compression and metering zones, and hold the nozzle at 235 °C to 245 °C. If the melt temperature exceeds 260 °C, thermal degradation accelerates. Mold temperatures should be controlled between 40 °C and 60 °C. At mold temperatures below 40 °C, rapid quenching creates a highly oriented skin and low crystallinity, which may produce post-mold shrinkage and weld-line weakness. Above 60 °C, the cycle time increases, and the additional crystallinity is typically small because PA12 crystallization rates are already high.
Injection unit design influences melt quality. Reciprocating screws with L/D ratios of 18:1 to 22:1 and compression ratios of 2.5:1 to 3.0:1 are used for PA12. High-compression screws generate shear heating; at screw speeds above 200 rpm on a 30 mm screw, melt temperature can rise beyond the set barrel temperature by 10 °C to 15 °C, increasing degradation risk. The maximum melt residence time at 240 °C should not exceed 10 min. During interruptions longer than 10 min, barrel temperatures should be reduced to 180 °C and the machine purged with a polyolefin purge compound. Hot-runner systems should be set no higher than 250 °C; hot-runner zones above 260 °C can produce black specks and gel formation in the runner channel.
Gate dimensions for thin-wall components are specified by the part thickness and flow length. For wall sections between 0.4 mm and 1.2 mm, edge gates of 0.6 mm to 1.0 mm diameter are common. Gate diameter below 0.5 mm creates high shear rates and may cause jetting; above 1.2 mm, packing time increases and gate blush may appear. Vent depths should not exceed 0.02 mm for PA12 to avoid flash while allowing air displacement. Mold-filling simulation should be performed with viscosity data generated by capillary rheometry at 230 °C and 250 °C; if the manufacturer’s Cross-WLF constants are unavailable, the simulation is unreliable for thin-wall predictions.
For extrusion of catheter shafts and tubing, a single-screw extruder with L/D between 24:1 and 30:1, a grooved feed section, and compression ratio of 2.5:1 to 3.5:1 is recommended. At screw speeds above 100 rpm, melt-pressure pulsation can cause outer diameter variation exceeding ±0.02 mm in multi-lumen profiles. Vacuum venting below 50 mbar is used only after the pellets have been pre-dried to below 0.1 % moisture. A screen pack with a 25 µm filter element downstream of the screw reduces gel inclusions. The melt temperature at the die should remain between 220 °C and 240 °C; die temperatures above 250 °C increase surface roughness and optical yellowing.
Steam autoclave exposure at 121 °C for 30 min or 134 °C for 3 min exposes PA12 to a combination of heat, water, and internal stress. The absorbed water plasticizes the amorphous phase and reduces modulus temporarily; repeated autoclave cycles can produce progressive dimensional relaxation, especially in parts with high molded-in orientation. For thin-walled components below 0.5 mm, post-sterilization curl can occur when cooling is non-uniform. Dimensional inspection after 3 to 5 autoclave cycles is therefore necessary before releasing a device that will be resterilized in hospital settings. The relevant cleaning and sterilization validation standard is ISO 17664-1 for reusable devices, but many single-use devices follow ISO 11137 or ISO 11135 depending on the terminal sterilization method.
Ethylene oxide sterilization is performed at 37 °C to 55 °C with controlled relative humidity above 30 %. The low water absorption of PA12 reduces the mass of water available for EtO partitioning compared with PA6, but device geometry, packaging headspace, and wall thickness control residual gas retention. Aeration must comply with ISO 10993-7 residual limits for ethylene oxide and ethylene chlorohydrin. Components with thick sections or encapsulated cavities require longer aeration cycles. Because PA12 is not inherently resistant to all chemicals, compatibility with the specific EtO sterilant gas mixture and humidity level should be confirmed by testing after a full cycle.
Gamma irradiation at doses up to 50 kGy can be applied to PA12, but oxidation of the amorphous phase may reduce elongation at break and produce yellowing. The actual property shift depends on dose rate, oxygen access, wall thickness, and antioxidant content. Electron beam processing at 10 MeV or lower uses higher dose rates and shorter exposure times, which can reduce oxidative degradation but may generate localized heating. The applicable radiation standard is ISO 11137, which establishes dose-setting and validation requirements based on bioburden. Post-sterilization mechanical testing should be performed according to ISO 527-1/-2 on tensile bars conditioned to ISO 291, and cytotoxicity must be retested on sterilized finished devices because radiation-induced oxidation products can alter biological test results.
When ML24 is evaluated as a replacement for PA11 in thin-walled catheter shafts, the main differences involve melting point, crystallization rate, and equilibrium water uptake. PA12 and PA11 are both low-amide-density polyamides, but PA12 crystallizes on cooling at a different rate and has a slightly lower melting point than some PA11 formulations. The shift in crystallization behavior changes the die-flow instability window and the draw-down ratio needed to maintain lumen roundness. For shafts with wall thickness between 0.08 mm and 0.25 mm, the draw-down ratio should be held between 2:1 and 8:1, and the draw ratio balance should be close to 1:1 to minimize orientation differences between inner and outer surfaces. A vacuum sizing tank with closed-loop pressure control below 5 kPa and water temperature between 10 °C and 20 °C is typically used to stabilize the outer diameter before crystallinity is fully developed.
Replacement validation for catheter shafts requires comparative testing under ISO 10555-1 and, for vascular access devices, ISO 10555-4 or the applicable device-specific standard. Corrugated or multi-lumen tubing may require modification of screw temperature profiles because PA12 has a narrower stable draw range than some PA11 grades at high take-off speeds. Dimensional stability after immersion in water at 37 °C for 24 h should be assessed because moisture absorption changes flexural modulus and inner diameter. If the catheter shaft is bonded to a hub or balloon, the adhesive or thermal bonding process must be revalidated because PA12 surface energy and melting point differ from PA11. Published data for this specific ML24 configuration in high-speed coextrusion with radiopaque fillers is limited; process capability studies on the production line are required before conversion.
The differences between ML24 and other medical-grade products are process- and application-specific. Compared with PA6 and PA66, the PA12 backbone provides lower equilibrium water absorption and better low-temperature impact retention, but lower tensile strength and lower continuous-use temperature. Compared with polyether block amide elastomers, ML24 has higher tensile modulus and lower elastic recovery, which may require a larger bend radius but provides better pushability in catheter shafts. Compared with glass-filled PA12, ML24 exhibits lower flexural modulus and lower abrasive wear on mating components, but higher linear thermal expansion; typical unfilled PA12 coefficient of linear thermal expansion measured by ISO 11359-2 is between 1.1 × 10⁻⁴ K⁻¹ and 1.2 × 10⁻⁴ K⁻¹. Within the VESTAMID Care ML series, the manufacturer positions ML24 as a lower-viscosity injection-molding grade, while higher-viscosity grades are documented for applications requiring higher melt strength in blow molding and large-diameter extrusion. Published direct grade-to-grade comparative data for all adjacent VESTAMID Care grades under identical sterilization and processing conditions is limited; therefore, each substitution should be qualified on the intended production line with tooling and lot-specific documentation.
