| HS Code | 807043 |
| Product Name | RESOMER L 209 S Bioresorbable Poly(L-lactide) Medical Grade |
| Chemical Name | Poly(L-lactide) |
| Abbreviation | PLLA |
| Cas Number | 26100-51-6 |
| Chemical Family | Aliphatic polyester |
| Appearance | White to off-white granules |
| Inherent Viscosity | 0.9 dL/g (0.1% in chloroform at 25°C) |
| Glass Transition Temperature | 55-60 °C |
| Melting Temperature | 175-180 °C |
| Density | 1.24-1.30 g/cm³ |
| Solubility | Soluble in chloroform, dichloromethane, dioxane; insoluble in water and ethanol |
| Residual Monomer | <0.5% |
| Moisture Content | <0.5% |
| Heavy Metals | <10 ppm |
| Tin Content | <50 ppm |
| Sulfated Ash | <0.1% |
| Biodegradation | Hydrolytic degradation to lactic acid |
| Storage Conditions | Store at -20°C, protected from moisture |
| Medical Grade | Produced under GMP conditions |
As an accredited RESOMER L 209 S Bioresorbable Poly(L-lactide) Medical Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged as 5 g in a sealed, moisture-barrier foil pouch with desiccant, labeled RESOMER L 209 S Medical Grade. |
| Container Loading (20′ FCL) | 20′ FCL loaded with RESOMER L 209 S Bioresorbable Poly(L-lactide) Medical Grade, palletized, dry, sealed, protected from moisture and heat. |
| Shipping | RESOMER L 209 S is shipped as a non-hazardous, medical-grade polymer in sealed, moisture-barrier containers. Keep dry, cool, and protected from light. Ship at ambient temperature unless the supplier specifies otherwise; follow storage conditions and handling precautions to prevent contamination. |
| Storage | Store RESOMER L 209 S in a tightly sealed container at −20°C, protected from moisture, heat, and light. Keep under a dry, inert atmosphere if possible. Allow to equilibrate to room temperature before opening to avoid condensation. Avoid repeated temperature cycling; moisture can hydrolyze this bioresorbable poly(L-lactide). Use original packaging and reseal immediately after use. |
| Shelf Life | Manufacturer’s shelf life is typically 24 months from manufacture when stored unopened, dry, cool, and protected from moisture. |
Melt processing of L 209 S for anterior cruciate ligament interference screws begins with vacuum drying at 80 °C for 4–6 h until residual moisture is ≤100 ppm, because ester hydrolysis at melt temperatures above 180 °C causes measurable molecular weight loss and shifts the device degradation profile. Incoming resin is routinely tested against ASTM F1925-22 for chemical composition, tin residues, and inherent viscosity; finished devices are released under ISO 13781:2017, ASTM F2502-17, ISO 10993-5, and ISO 10993-11. The formulation addition ratio is 100 wt% neat L 209 S, without plasticizers or impact modifiers; regrind, sprue, and runner reintroduction is excluded from human-implantable lots because even low levels of hydrolytically degraded PLLA increase oligomer content and reduce fatigue life. Injection molding uses a reciprocating screw with L/D 20:1 to 24:1, compression ratio 2.2:1 to 2.8:1, and a melt temperature measured at the nozzle of 185–210 °C. Mold temperature is held at 30–60 °C to balance fill length against crystallinity; injection speed is set to 60–150 mm/s, holding pressure 800–1,200 bar, and cooling time 25–60 s depending on thread depth and core pin length. Cannulated designs place the gate on the rib of the screw head and use a collapsible core or unscrewing mechanism; cold-runner systems with generous runner cross-sections are preferred over hot runners because long residence times above 200 °C produce localized viscosity loss and contamination speck formation. After demolding, screws are annealed under nitrogen at 110–120 °C for 2–4 h to stabilize crystallinity and reduce residual stress before packaging in double-tyvek pouches. For design verification, tensile specimens cut from plaques are tested under ASTM D638-14; amorphous L 209 S moldings typically exhibit tensile yield in the 55–65 MPa range and elongation at break below 5%. Terminal products are bioresorbable interference screws with diameters from 7 mm to 12 mm and lengths from 20 mm to 35 mm, used for femoral and tibial fixation during ligament reconstruction.
For craniofacial distraction and trauma systems, low-crystallinity plate stock is produced by compression molding L 209 S between polished tool-steel platens at 190–200 °C under 10–20 bar hydraulic pressure, followed by controlled cooling at 1–2 °C/min to limit spherulite growth; the slower the cooling, the higher the crystalline fraction and the lower the ductility. Plates are then machined on CNC mills with carbide tooling at spindle speeds of 8,000–15,000 rpm and low feed rates, using chilled-air or isopropanol mist cooling to prevent surface melting of the bioresorbable matrix. The formulation addition ratio is 100% L 209 S; no plasticizer is used, and only clean-room compatible machining fluids without chloride or aromatic residues are permitted. Although osteoconductive fillers such as beta-tricalcium phosphate can be added to PLLA at 5–10 wt% in other implant families, this practice is not standard for thin craniofacial plates because filler particles create stress concentrations at screw holes and reduce bending strength. Compliance for this product family references ASTM F2502-17 for absorbable plates and screws, ISO 13781:2017 for lactide polymer chemistry, ISO 13485:2016 for quality management, and FDA 21 CFR Part 820 for design controls and device history records. Terminal finished types include 1.5 mm and 2.0 mm fixation plates, 2.0 mm and 2.4 mm self-tapping screws, and pre-contoured orbital floor sheets; these are packaged sterile and used for midface fracture fixation and pediatric craniosynostosis reconstruction where removal surgery is undesirable.
In shoulder arthroscopy anchors, the primary process limitation is not plastication but premature gate freeze: L 209 S solidifies rapidly at mold temperatures below 35 °C, and thin-walled eyelet features of 2.8–5.0 mm diameter require gate diameters of 1.0–2.0 mm to maintain flow until packing is complete. The formulation addition ratio is 100% virgin L 209 S with 0% regrind; every manufacturing lot that introduces runners or sprues back into the feed stream must revalidate viscosity, residual tin, and bioburden against ASTM F1925-22 and the internal implant master file. Injection molding lines use 16-cavity cold-runner molds with clamp force of 350–600 kN, melt temperatures of 185–205 °C, injection speeds of 80–150 mm/s, and cooling times of 12–20 s. The key output check is fill reproducibility across cavities; a batch drift in inherent viscosity from nominal 0.9 dL/g to 0.85 dL/g can shift short-shot frequency, which is monitored through cavity pressure sensors sampling at 100 Hz. Terminal products include knotless anchors and screw-type anchors with preloaded suture eyelets, used for rotator cuff repair, Bankart labrum repair, and glenoid fixation. Biological evaluation follows USP <88> Class VI, ISO 10993-5, and ISO 10993-10; mechanical pull-out testing uses commercially available polyurethane foam with density 0.16 g/cm³ as a cancellous bone analogue, but published data for this specific L 209 S anchor configuration is limited.
| Parameter | Boundary | Monitoring |
|---|---|---|
| Melt temperature | 185–205 °C | Nozzle pyrometer, ±2 °C |
| Mold temperature | 20–35 °C | Thermocouple per cavity |
| Gate diameter | 1.0–2.0 mm | Dimensional inspection ±0.01 mm |
| Cooling time | 12–20 s | PLC cycle log |
Soft-tissue volumizing applications use cryogenically milled L 209 S microparticles with a mass median diameter controlled between 20 µm and 63 µm; particles below 5 µm are removed by cyclone classification because they generate macrophage uptake and reduce implant persistence, while particles above 100 µm increase clumping during syringe delivery. The formulation addition ratio for a lyophilized injectable presentation is typically 100–150 mg PLLA per vial, blended with sterile sodium carboxymethylcellulose 80–100 mg and mannitol 110–130 mg as dispersing and bulking agents; after reconstitution with 5–8 mL water for injection, the suspension is immediately injected into subcutaneous or supraperiosteal planes. Compliance references ISO 10993-1:2018 for implant evaluation, ISO 10993-6 for local effects, and USP <88> Class VI for plastic biological reactivity; particle size distribution is measured by laser diffraction according to ISO 13320:2020. The downstream production process includes melt extrusion into rods, immersion cooling, cryogenic grinding at −60 °C to −80 °C, sieving under ISO 14644-1 Class 8 at minimum, and aseptic filling; gamma irradiation at 25–35 kGy is generally avoided because molecular weight loss in PLLA can shift degradation kinetics and particle embrittlement. Terminal product type is an injectable PLLA microparticle suspension for facial volume restoration, requiring reconstitution at point of care rather than a pre-filled syringe. Published data for the exact milling throughput of L 209 S in specific cryogenic mills is limited.
Encapsulation of heat-sensitive peptides into L 209 S microspheres uses an oil-in-water solvent extraction/evaporation route in which the organic phase contains 8–18% w/v polymer in dichloromethane and the aqueous continuous phase contains poly(vinyl alcohol) at 0.5–2.0% w/v. The drug-to-polymer addition ratio is 1:3 to 1:10, with the exact value set by the required release duration and peptide stability profile; higher polymer fractions extend release but increase the burst of low-molecular-weight fractions and slow solvent removal. The emulsion is formed in a high-torque stirred tank at 400–1,000 rpm, then transferred into an extraction tank containing water at 10–18 °C for 4–8 h to harden the microspheres; temperature control during extraction is critical because premature heating collapses the pores and traps solvent. After centrifugal washing, the microspheres are lyophilized and aseptically filled; residual dichloromethane is quantified by headspace gas chromatography against ICH Q3C limits, and particulate matter is tested under USP <788> and USP <789>. Compliance also includes ISO 13781:2017 for the raw lactide polymer identity and ISO 10993-6 for local tissue reaction; terminal products are lyophilized depot microspheres with particle diameters controlled between 10 µm and 50 µm, intended for intramuscular or subcutaneous injection of LHRH agonists or other peptide APIs requiring 1–6 month release. For specific drug substances with amine-rich residues, the formulation must be screened for premature polymer chain scission due to nucleophilic attack, and published data for that specific L 209 S configuration is limited.
In melt-spinning lines configured for absorbable monofilament suture, the solidified filament must pass through a multi-stage draw process to achieve tensile strength in the 400–600 MPa range when tested under ASTM D2256/D2256M; the process begins with single-screw extrusion of L 209 S through a die orifice of 1.0–2.5 mm at melt temperatures of 180–200 °C, followed by water quenching at 20–40 °C to suppress spherulitic growth. The formulation addition ratio is 100 wt% neat L 209 S; if violet color is required, D&C Violet No. 2 is added at <0.1 wt% as a masterbatch, because higher dye loadings can reduce drawability and create particulate defects in USP size 6-0 and 7-0 monofilaments. First-stage drawing at 60–90 °C is followed by second-stage drawing to a total draw ratio of 4:1 to 6:1, and the filament is annealed under tension at 110–120 °C to set molecular orientation and reduce post-implantation axial shrinkage. Compliance is built around ISO 13781:2017 for starting polymer chemistry, USP <88> Class VI for biological reactivity, and ISO 10993-11 for systemic toxicity; the terminal product type is absorbable monofilament suture in USP sizes 6-0 to 1, used for ophthalmic, pediatric, and general soft-tissue approximation where a persistent monofilament knot is undesirable after wound support is complete.
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RESOMER L 209 S is a semicrystalline medical-grade poly(L-lactide) (PLLA) supplied by Evonik Industries as white-to-off-white granules. The grade is specified at an inherent viscosity of 0.90–1.10 dL/g when measured at a polymer concentration of 0.1% in chloroform at 25 °C, using a single-point capillary viscometric method aligned with ISO 1628-1 and the supplier’s release protocol. Differential scanning calorimetry at 10 K/min under nitrogen places the glass transition at 60–65 °C and the crystalline melting endotherm at 180–185 °C. The matrix is a homo-polyester of L-lactide; it is soluble in chlorinated solvents and insoluble in water, alcohols, and aliphatic hydrocarbons. Because it is produced under ISO 13485:2016 quality-system control and released with limits for residual lactide, residual solvents, moisture, heavy metals, and tin catalyst residue, L 209 S differs from technical-grade PLLA in lot-to-lot molecular-weight consistency and in the availability of biocompatibility documentation aligned with ISO 10993-1:2018.
Inherent viscosity is not equivalent to intrinsic viscosity; it is calculated from the relative viscosity of a single polymer solution and is therefore sensitive to concentration, solvent, temperature, and filtration conditions. For L 209 S, the 0.1% chloroform protocol produces a targeted range of 0.90–1.10 dL/g. A lower inherent-viscosity PLLA such as RESOMER L 207 S has lower melt viscosity and shorter hydrolytic mass loss, but reduced initial tensile strength and lower load-bearing capacity. A higher inherent-viscosity PLLA such as RESOMER L 210 S requires higher processing pressures and is more sensitive to shear heating, but it can provide longer strength retention in vivo. The L 209 S specification places the grade in an intermediate-high molecular-weight band that can be injection moulded on conventional medical-device machines while still providing a tensile strength of approximately 60–70 MPa on annealed test bars tested at 5 mm/min according to ASTM D638-14. At a density of 1.24 g/cm³, the semicrystalline morphology also differentiates L 209 S from amorphous poly(D,L-lactide) grades; the latter do not exhibit a melting endotherm and lose dimensional stability above their glass transition of approximately 50–55 °C.
The relationship between inherent viscosity and hydrolysis half-life is nonlinear. Above 1.0 dL/g, each small increment in viscosity corresponds to a larger increase in number-average molecular weight and in the time required for water to penetrate semicrystalline regions. Below 0.7 dL/g, the material becomes difficult to extrude into self-supporting structures and may be better suited to drug-delivery microspheres. L 209 S has enough chain entanglement to maintain melt strength during extrusion while remaining below the very high viscosity of L 210 S, which can require melt temperatures near 210 °C and longer plasticating times.
Process temperatures for L 209 S should be kept as low as possible while still obtaining complete melt. A barrel profile of 180–210 °C is typical; a melt temperature above 220 °C accelerates random chain scission and lactide regeneration, particularly when residence time exceeds 5–10 min. The degradation is autocatalytic because lactide and lactic acid generated during heating lower local pH and catalyse further ester hydrolysis. On an injection-moulding machine with a 20:1 to 25:1 L/D general-purpose screw and a screw compression ratio of 2.5:1, a cushion of 3–5 mm and back pressure of 2–5 bar are maintained to ensure shot-to-shot consistency. A mould temperature of 20–30 °C reduces cycle time and yields a largely amorphous skin, whereas a mould temperature of 100–120 °C promotes spherulite growth, higher modulus, and greater solvent resistance but requires longer cooling time and may increase warpage. Hot-runner systems must be designed without dead spots; any heated region that cannot be purged should be held below 200 °C during interruptions. After processing, the machine is purged with a suitable polyolefin or acrylic purge compound; residual PLLA must not be left in the barrel under heat because it will degrade, darken, and cause carbonaceous deposits.
Because PLLA is hygroscopic, moisture control during storage and drying determines whether the product retains its release viscosity through melt processing. In a production-scale 25 mm twin-screw extruder with L/D 30 and barrel set points of 190–210 °C, undried granules exposed to 60% RH for 24 h show visible viscosity loss at the die, while granules dried to below 250 ppm water by Karl Fischer titration exhibit a viscosity shift of less than 2% after one extrusion cycle. Therefore, the granulate should be dried in a desiccant-bed dryer with inlet air dew point below -40 °C, or in a vacuum oven at 80–100 °C for 4–8 h, to a residual moisture target of ≤0.025% before melt processing. A nitrogen purge on the hopper and short residence-time profiles are required. If the material is left overnight in an open hopper at relative humidity above 60%, pre-drying must be repeated because surface moisture uptake is rapid enough to shift the melt viscosity and produce bubbles in injection-moulded parts.
The values in the following table are representative release limits or typical values for RESOMER L 209 S; the certificate of analysis for each lot should be consulted because specifications may be adjusted for regional pharmacopoeial or custom device requirements.
| Parameter | Release limit or typical value | Method |
|---|---|---|
| Appearance | White to off-white granules | Visual inspection |
| Inherent viscosity | 0.90–1.10 dL/g | ISO 1628-1 / supplier method |
| Residual lactide monomer | ≤0.5 wt% | GC-FID after dissolution and precipitation |
| Residual solvents | ≤0.1 wt% | Headspace GC |
| Water content | ≤0.5 wt% | Karl Fischer titration, ISO 15512 |
| Heavy metals, as Pb | ≤10 ppm | ICP-OES after digestion |
| Tin catalyst residue | ≤200 ppm | ICP-MS |
| Sulfated ash | ≤0.1 wt% | Ph. Eur. 2.4.14 |
| Density | 1.24 g/cm³ typical | ISO 1183-1 |
When melt processing is not suitable, solvent-based fabrication of L 209 S provides an alternative route for microspheres and drug-loaded implants without thermal stress. The polymer is dissolved in dichloromethane at 5–15% w/v and emulsified into an aqueous poly(vinyl alcohol) continuous phase using a rotor-stator mixer at 5,000–15,000 rpm. After solvent evaporation or extraction, the microspheres are washed, sieved, and vacuum-dried. Residual dichloromethane is controlled by headspace gas chromatography and should meet ICH Q3C limits for pharmaceutical products; the exact acceptance limit depends on the dosage form and route of administration. Because L 209 S has high inherent viscosity, the organic phase is more viscous than lower-molecular-weight polylactides, so higher solvent-to-polymer ratios and lower emulsification temperatures are typically required to keep droplets below 100 µm for parenteral use. Incompatibilities for solvent processing include strong bases, primary amines, and protic solvents that accelerate ester cleavage; chlorinated solvents are acceptable for dissolution but must be removed to residue levels before implantation.
Compared with L 210 S, the L 209 S grade has a lower inherent viscosity and therefore lower melt pressure in injection moulding and extrusion. That makes L 209 S preferable for thin-wall components and multi-cavity moulds, but it may retain load-bearing strength for a shorter period in large orthopaedic implants. L 210 S, in contrast, is used where maximum tensile and flexural strength are needed, but its higher molecular weight raises melt pressure and may require wider gates and higher clamping force. Compared with amorphous RESOMER R 207 S poly(D,L-lactide), L 209 S carries only L-lactide repeat units, producing a semicrystalline matrix with a glass transition of 60–65 °C and a melting point of 180–185 °C. The amorphous R 207 S has no crystalline melting endotherm and is generally processed at lower temperatures; it also absorbs water more rapidly and degrades faster because water penetration is not restricted by crystallites. Therefore L 209 S is selected when slower bioresorption, higher modulus, and dimensional stability above 55 °C are required, whereas the amorphous grade is selected for drug-eluting coatings or microspheres where faster matrix dissolution and lower processing temperature are beneficial. Differences from PLGA copolymers are even more pronounced: glycolic acid units lower crystallinity and increase hydrolysis rate; L 209 S lacks glycolide, so degradation is slower and acidic degradation products are generated less rapidly, although published data on local pH for this exact grade are limited.
Sterilization must be selected carefully because PLLA is subject to radiation-induced chain scission and hydrolysis. Gamma irradiation at 25 kGy produces a measurable reduction in molecular weight; reported loss is typically less than that of amorphous poly(D,L-lactide) under the same dose but should be evaluated on the finished device according to ISO 11137-1. Ethylene oxide sterilization may be used if residuals are removed and moisture exposure is controlled; steam sterilization is not appropriate because the glass transition is near 60–65 °C and the combination of heat and water rapidly hydrolyses the polyester. After sterilization, the device should be packaged with desiccant and stored in sealed aluminum-foil pouches. Devices should not be stored in unsealed containers at room temperature and high humidity because moisture absorption can shift degradation kinetics before use. For terminal processing, the finished-device manufacturer is responsible for validating that sterilization load geometry, dose mapping, and packaging do not alter the release specification.
The following matrix summarises the standards commonly applied to RESOMER L 209 S and finished devices produced from it.
| Standard | Scope | Application to L 209 S |
|---|---|---|
| ISO 13485:2016 | Quality management system for medical devices | Supplier manufacturing and batch release |
| ISO 10993-1:2018 | Biological evaluation of medical devices | Risk-based endpoint selection for finished devices |
| ISO 10993-5 | In vitro cytotoxicity | Extract testing of device prototypes |
| ISO 10993-10 | Sensitisation and irritation | Skin sensitisation testing for implantables |
| ISO 11137-1 | Radiation sterilisation validation | Gamma or e-beam dose setting |
| ISO 11135 | Ethylene oxide sterilisation validation | EO residue control for moisture-sensitive PLLA |
| ISO 1628-1 | Viscosity of polymers in dilute solution | Inherent viscosity release parameter |
| ASTM D3418 | Thermal transitions by DSC | Tg and Tm characterisation |
| ASTM D638-14 | Tensile properties of plastics | Mechanical testing of injection-moulded specimens |
| ISO 1183-1 | Plastics density by immersion | Density control |
| ICH Q3C | Residual solvents in pharmaceuticals | Dichloromethane limit after solvent processing |
Storage of unopened containers in sealed aluminum-foil bags under dry inert gas is recommended; any excursions above 25 °C for prolonged periods should be avoided because amorphous-phase chain mobility and residual moisture accelerate pre-processing hydrolysis. If a container is opened and not fully consumed, the remaining granulate should be resealed immediately with desiccant and re-dried before subsequent use. These handling constraints are operational boundaries derived from polyester hydrolysis kinetics and are not limited to RESOMER L 209 S; they apply broadly to semicrystalline PLLA medical polymers.
