Evonik VESTAMID Care ML-GB30 Nylon 12, 30% Glass Bead Filled, Dry is a medium-viscosity polyamide 12 compound in which 30% by mass spherical glass bead filler is dispersed in a PA12 matrix intended for medical technology applications. The designation Dry refers to the reporting basis for mechanical and thermal data; values are generated on specimens in the dry-as-molded state, and the term does not imply that the resin can be processed without moisture control. The product belongs to the VESTAMID Care portfolio, which is supplied under formulation control and documentation practices intended to support medical device manufacturers in design and regulatory submissions. The glass bead filler increases stiffness and lowers mold-shrinkage anisotropy relative to unfilled PA12, while retaining the comparatively low equilibrium moisture uptake of PA12 relative to PA6 and PA66. Because beads are spherical, the volume fraction created by 30% by mass glass is roughly 13–15 vol%, depending on the exact glass density and matrix crystallinity; this lower volume fraction is a key reason the bead-filled grade does not reach the modulus level of an equivalent weight percentage of glass fibre.

Typical Dry-As-Molded Property Set and Test Method Anchors

The values in Table 1 are representative supplier technical literature values for the dry-as-molded state and are not specification limits. Lot-specific acceptance criteria must be taken from the current Evonik technical data sheet or the purchase specification.

When Moisture Uptake Shifts Mechanical Response in Service

Dry-as-molded data are not sufficient for design in humid service. PA12 absorbs moisture by diffusion; under standard laboratory atmosphere of 23 °C and 50 % relative humidity, equilibrium uptake for PA12 grades is generally below 1.0 % by mass, while saturation in liquid water at 23 °C is reported near 1.1 % by mass. Absorbed water plasticizes the amorphous regions, lowers glass-transition-related stiffness, and increases notched impact toughness and elongation. A component dimensionally validated in the dry state may grow slightly after moisture conditioning; this is partly reversible upon drying. For precision medical device components, dimensional measurements should therefore be delayed until the part reaches a defined moisture condition, or the drawing should specify both dry and conditioned acceptance limits.

In steam-sterilized or condensing environments, the modulus reduction may be larger than that predicted from equilibrium room-temperature uptake because elevated temperature accelerates water diffusion and hydrolysis kinetics. The operational boundary is therefore not simply the dry tensile modulus but the conditioned modulus at the upper service temperature.

Incoming resin quality control for medical production often includes moisture analysis by Karl Fischer titration or loss-on-drying at the hopper, pellet size distribution, and glass bead content verification by thermogravimetric analysis or ashing. Inconsistent bead content in a lot can shift viscosity and shrinkage; therefore, certificate-of-analysis review against established limits is more useful than relying solely on the trade name. The buyer should obtain the current technical data sheet and specification for the exact production site because property values can vary by manufacturing location and pelletization lot.

What Processing Limits Apply to Glass Bead-Filled Nylon 12?

The most immediate processing boundary is residual moisture. Supplier guidance for PA12 compounds commonly specifies pre-drying at 80 °C to a residual moisture content below 0.10 % by mass. A desiccant dryer with a dew point of -30 °C or lower and closed conveying is used on production lines. At relative humidity above 60 %, open hoppers and long hopper residence times can reintroduce moisture and produce splay, surface streaks, and melt-pressure variation. Inadequate drying also accelerates hydrolysis of the polyamide chain during plastication, shifting viscosity downward and reducing molecular weight.

Melt temperature at the nozzle is typically maintained between 220 °C and 250 °C, while mold temperature is held between 60 °C and 90 °C. The upper temperature limit is residence-time dependent; at nozzle temperatures above 250 °C, yellowing and molecular weight loss may occur after several minutes of hold-up. The lower mold-temperature bound supports faster cycle time but can increase post-molding shrinkage and warpage; the upper bound improves crystallinity development and dimensional stability but extends required cooling time. Molding trials should bracket mold temperature and holding pressure to establish a process window for the specific tool.

Production-scale injection molding of bead-filled PA12 is performed on general-purpose three-zone screws with L/D ratios from 18:1 to 22:1 and compression ratios from 2:1 to 2.5:1. Glass beads are abrasive; screw-tip, check-ring, and barrel wear are monitored. Deterioration of the non-return valve appears as increasing cushion inconsistency and screw-recovery instability at unchanged barrel settings. Unlike glass fibre grades, bead-filled melt does not orient strongly during flow, so cavity-to-cavity fill variation and shrinkage anisotropy are generally lower. Venting is still critical; inadequate venting in multi-cavity hot-runner tools can produce burn marks and low-molecular-weight deposits on the mold surface.

Injection-rate selection is coupled to the rheology of the bead-filled melt. Glass beads increase thermal conductivity but do not create the sharp viscosity rise at high filler loadings typical of long fibres. Process development often uses cavity-pressure transducers to confirm gate-freeze time and packing pressure; a stable gate-freeze time is a better predictor of part weight and seal surfaces than barrel temperature alone. For thin-wall parts below 1.5 mm nominal wall thickness, filling may require melt temperatures near the upper end of the window and elevated injection velocities, but the exact values depend on flow length, gate diameter, and hot-runner pressure drop. Published data for this specific configuration is limited, so mold-filling simulation should be calibrated with spiral-flow or short-shot studies on the production mold.

Regrind use in medical device manufacturing is normally prohibited unless the device manufacturer has validated the effect of regrind on biocompatibility, mechanical properties, and traceability under its quality agreement. The addition of regrind can change bead size distribution and melt viscosity and is not automatically covered by the supplier’s formulation-control documentation.

Comparative Behaviour Against Unfilled PA12 and Glass Fibre Reinforced Grades

The practical differences among polyamide 12 grades are best captured by stiffness, shrinkage isotropy, and surface quality. Unfilled PA12 typically reports dry tensile modulus between 1400 MPa and 1600 MPa; the 30% glass bead-filled grade reports dry tensile modulus near 2100 MPa. A 30% glass fibre-reinforced PA12 may report dry tensile modulus from 4500 MPa to 6000 MPa depending on fibre length and processing orientation, but this increase is accompanied by anisotropic shrinkage and higher warpage in flat parts. The spherical bead filler produces a lower aspect ratio and therefore less stress concentration at the filler-matrix interface, but it also provides less load-transfer efficiency per unit volume than high-aspect-ratio fibre.

Table 2 summarizes the directional tendencies of these material classes. The entries are generic class comparisons, not exact specifications for every supplier grade.

Compared with glass bead-filled grades based on PA6 or PA66, the PA12 matrix provides lower water uptake and hence less humid ageing-induced stiffness loss, although PA6 and PA66 have higher dry modulus and heat deflection temperature. Compared with glass bead-filled PBT or polycarbonate, PA12 generally offers lower density and better low-temperature impact; however, PBT may provide lower moisture uptake and better chemical resistance to some solvents. The selection among these materials for a medical housing therefore depends on whether exposure is wet, chemically aggressive, or thermally elevated, and on whether the part must survive drop impact at sub-zero temperatures.

In thin-walled diagnostic housings, surgical handpiece enclosures, and drug-delivery device structural components, the use of a 30% glass bead-filled PA12 is typically driven by the need to maintain flatness, hole-to-hole location, and snap-fit clearance after ejection and cooling. Multi-cavity tools running on injection molding machines with clamp force in the 500–1200 kN range have shown lower variation in flatness and less flow-direction/transverse-direction shrinkage differential than comparable glass fibre-filled parts, but mold design remains the dominant factor. Gate placement, wall-thickness transitions, and cooling-channel layout control shrinkage more than the filler alone. Published data for this specific configuration is limited; capability studies on the production tool are required to establish actual tolerance performance.

Sterilization exposure is a further design input. Ethylene oxide processing leaves residues that must be reduced below the limits established in ISO 10993-7; gamma and e-beam radiation can cause chain scission and color shift, with dose mapping required to avoid excessive embrittlement; steam autoclaving introduces moisture and cyclic thermal stress. Repeated steam sterilization at 121 °C or 134 °C can reduce molecular weight over multiple cycles, so the number of cycles must be validated on the finished device. Biocompatibility is not supplied as a resin property; the final device must be assessed under ISO 10993-1 with relevant endpoints such as ISO 10993-5 for cytotoxicity, ISO 10993-10 for skin sensitization and irritation, and ISO 10993-11 for systemic toxicity. The supplier may provide material-oriented documentation, but device-level validation remains the manufacturer’s responsibility.

The grade is not recommended for continuous service in strong oxidizing acids, concentrated formic acid, or high-temperature water above 80 °C without specific testing. UV exposure without carbon black or stabilizer can lead to surface chalking and embrittlement; medical housings used in light-exposed applications require stabilization validated in the final colour formulation.