| HS Code | 432792 |
| Productname | RESOMER L 206 S Ester-Terminated Poly(L-lactide) Medical Grade |
| Chemicalname | Poly(L-lactide) |
| Synonym | PLLA |
| Casnumber | 26100-51-6 |
| Molecularformula | (C3H4O2)n |
| Endgroup | Ester |
| Stereochemistry | L-lactide homopolymer |
| Appearance | White to off-white granules |
| Form | Granules/pellets |
| Molecularweight | approx. 100,000 g/mol |
| Inherentviscosity | approx. 1.0 dL/g (0.1% in chloroform at 25 °C) |
| Glasstransitiontemperature | approx. 55–60 °C |
| Meltingtemperature | approx. 175–180 °C |
| Density | approx. 1.24 g/cm3 at 20 °C |
| Solubility | Soluble in chloroform, dichloromethane, dioxane; insoluble in water and ethanol |
| Biodegradability | Hydrolytically biodegradable to lactic acid |
| Storage | Store at 2–8 °C, protected from moisture |
| Residualmonomer | < 0.2% |
| Residualsolvent | < 0.1% |
| Watercontent | < 0.5% |
| Heavymetals | < 10 ppm |
As an accredited RESOMER L 206 S Ester-Terminated Poly(L-lactide) Medical Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | RESOMER L 206 S Ester-Terminated Poly(L-lactide) Medical Grade is supplied in 1 g glass bottles with secure, protective labeling. |
| Container Loading (20′ FCL) | 20′ FCL loading: palletized RESOMER L 206 S medical-grade poly(L-lactide), dry container, ambient conditions, no moisture, contamination, or direct sunlight. |
| Shipping | RESOMER L 206 S is not classified as dangerous goods for transport. It is shipped in sealed aluminum foil bags under nitrogen at ambient temperature. Protect from moisture, heat, and light. Store at -20°C upon receipt. This medical-grade polymer is moisture- and heat-sensitive; keep container tightly closed and desiccated. |
| Storage | Store RESOMER L 206 S in a cool, dry, well-ventilated area away from heat, ignition sources, and moisture. Keep the container tightly closed, preferably under inert gas, and protect from light. Recommended storage temperature is 2–8°C; for longer periods, −20°C may be used. Use within the supplier’s stated shelf life. |
| Shelf Life | Shelf life is typically 24 months when stored unopened at -20°C, protected from moisture; confirm on supplier lot-specific documentation. |
In load-bearing resorbable orthopedic fixation, ester-terminated poly(L-lactide) of the RESOMER L 206 S specification is processed either as a neat polymer or as a ceramic-filled compound for resorbable interference screws, suture anchors, ligament tacks, and small-bone compression screws. The L 206 S grade carries an inherent viscosity of 0.8–1.2 dL/g measured at 0.1% in chloroform at 25 °C, positioning it for high-strength molded devices. The terminal esterification removes the free carboxylic acid chain ends that would otherwise accelerate autocatalytic hydrolysis during the first 12–26 weeks of implantation; the practical effect is a more gradual initial water-uptake profile and a longer molecular-weight retention plateau when tested under ASTM F1635-16 in phosphate-buffered saline at 37 °C ± 1 °C. Compounding for this sector includes neat resin for maximum initial flexural modulus and, where an osteoconductive interface is required, dispersion of 10–30 wt% β-tricalcium phosphate or hydroxyapatite on a co-rotating twin-screw extruder with a 25:1 L/D ratio and barrel temperatures of 175–205 °C. Vacuum devolatilization is used to keep residual moisture below 0.01 wt% before pelletization. Pellets are pre-dried at 80 °C under vacuum for 4 h, then injection-molded at melt temperatures of 190–210 °C into mold cavities held at 85–110 °C. Post-molding annealing at 110 °C for 2–4 h increases crystallinity and stabilizes dimensions during ethylene oxide sterilization under ISO 11135:2014; gamma irradiation requires dose mapping under ISO 11137-1:2006/Amd 1:2013 because high doses can reduce inherent viscosity. Melt and glass transition temperatures are verified by differential scanning calorimetry according to ISO 11357-2:2020, while melt viscosity consistency is confirmed by melt mass-flow rate according to ISO 1133-1:2022. On production-scale cells with 80–120 t hydraulic clamp force, thin-wall core pins are run with injection velocities that avoid shear-induced molecular orientation leading to anisotropic shrinkage. Mechanical acceptance is assessed under ASTM F2502-17; biocompatibility is evaluated under ISO 10993-1:2018, ISO 10993-5:2009, ISO 10993-6:2016, ISO 10993-10:2010, and ISO 10993-11:2017. Residual lactide monomer and degradation behavior are controlled under ISO 13781:2017, risk management follows ISO 14971:2019, and sterile barrier packaging is validated under ISO 11607-1:2019. The dominant production failure mode is hydrolytic degradation during interruptions, particularly when residence time exceeds 6–8 min at melt temperature; barrel shutdown and cold-start protocols must therefore be validated for multi-cavity tools.
| Assessment stage | Standard/method | Specific data parameter |
|---|---|---|
| Polymer identity and degradation | ISO 13781:2017 | Residual lactide monomer, inherent viscosity, degradation profile |
| In vitro hydrolytic degradation | ASTM F1635-16 | Mass loss, pH shift, molecular weight retention in PBS at 37 °C |
| Cytotoxicity | ISO 10993-5:2009 | L929 cell viability |
| Local effects after implantation | ISO 10993-6:2016 | Histopathology at 4, 12, and 26 weeks |
| Mechanical function | ASTM F2502-17 | Torsional yield and screw insertion torque |
Solvent-evaporation and solvent-extraction manufacturing of long-acting injectable microspheres from RESOMER L 206 S uses an oil-in-water emulsion in which the polymer and active pharmaceutical ingredient are dissolved in dichloromethane at polymer concentrations of 10–25 wt% and drug loadings of 10–40 wt% relative to polymer mass. The aqueous continuous phase contains 0.5–3.0 wt% poly(vinyl alcohol) as emulsion stabilizer; primary emulsification is performed in a rotor-stator mixer at 3,000–10,000 rpm, and the emulsion is transferred to a stirred hardening tank under controlled temperature at 2–8 °C. Droplet size is monitored by laser diffraction according to ISO 13320:2020 to maintain a D50 between 20 µm and 80 µm; particle size span is controlled because coarse fractions above 150 µm increase syringeability defects, while fines below 10 µm raise initial burst release. The ester-terminated PLLA grade suppresses the acid-catalyzed bulk degradation channel during the first release phase relative to acid-terminated PLGA grades, so release profiles can exhibit reduced early burst but prolonged lag time at high drug loadings. In vitro release testing uses USP Apparatus 4 flow-through cells with a flow rate of 40 mL/min and a 0.02 wt% sodium azide phosphate-buffered saline medium at 37 °C; samples are analyzed for drug content by high-performance liquid chromatography with method validation under ICH Q2(R1). Aseptic processing and terminal sterilization steps are designed around 21 CFR Part 210/211 and ISO 13485:2016; release testing includes USP <71> sterility, USP <85> bacterial endotoxin, USP <788> particulate matter in injections, and residual solvent analysis under ICH Q3C(R8). The finished dosage form is a sterile lyophilized powder that is reconstituted with water for injection as a depot suspension; batch moisture after lyophilization is held below 2.0 wt% to prevent polymer hydrolysis during shelf storage. Production-scale failure modes include emulsion aging in buffer hold tanks and residual dichloromethane drift due to insufficient hardening time, both of which require inline near-infrared monitoring and periodic gas chromatography. The terminal products addressed by this process are controlled-release injectables for psychiatric, endocrine, and pain-management actives.
Thin-strut bioresorbable scaffolds for temporary vascular support are manufactured from RESOMER L 206 S as a neat resin with a formulation addition ratio of 100% polymer; no filler, plasticizer, or processing aid is compounded into the tube stock. Radiopacity is supplied by platinum-iridium markers placed at the scaffold ends rather than by dispersion of contrasting agents, because added particulate fillers reduce strut ductility and accelerate fatigue crack initiation. Tube extrusion is carried out on a single-screw extruder with a 24:1 L/D ratio and barrel temperatures from 180 °C to 205 °C, yielding an oriented tube that is subsequently laser-cut with a femtosecond source into strut patterns of 150–180 µm width. The cut scaffold is expanded at 60–70 °C, annealed at 100–120 °C, and crimped onto a delivery balloon; ethylene oxide sterilization under ISO 11135:2014 is preferred over high-dose gamma irradiation because molecular-weight loss under irradiation alters the degradation timeline and can create stress-whitening in thin struts. Mechanical evaluation follows ISO 7198:2016 for vascular prostheses and includes radial strength, crush recovery, and fatigue testing under simulated physiological loading. Degradation assessment follows ISO 13781:2017 and ASTM F1635-16, while the device-level regulatory framework includes ISO 25539-1:2017 for endovascular prostheses, ISO 10993-1:2018, ISO 10993-5:2009, ISO 10993-6:2016, and ISO 10993-11:2017. The finished product types include drug-eluting bioresorbable scaffolds and non-drug-coated bioresorbable scaffolds for below-the-knee peripheral applications. A principal process boundary is the melt-temperature window: above 210 °C molecular weight drops rapidly, while below 185 °C melt strength is insufficient for uniform tube wall thickness; therefore in-line melt pressure and diameter gauges are mandatory on production lines. Published degradation data for this specific ester-terminated PLLA grade in thin-strut vascular geometry are limited, so process characterization relies on worst-case lot selection and accelerated in vitro testing.
Solvent-cast and electrospun membranes composed of RESOMER L 206 S serve as resorbable barriers in guided bone regeneration and guided tissue regeneration. In solvent casting, polymer is dissolved at 10–15 wt% in chloroform or dichloromethane with 0.1–0.5 wt% triethyl citrate added to reduce film embrittlement. The solution is knife-coated onto a polyethylene terephthalate release liner at a gap of 200–400 µm and dried in an ISO 14644-1 Class 8 cleanroom to control particulate contamination. Electrospinning variants use a 10–14 kV applied voltage, a 0.5–1.5 mL/h flow rate, and a 20–25 cm needle-to-collector distance to produce fiber diameters of 300–700 nm; collected membranes are vacuum-dried at 35–40 °C for 24 h to remove residual solvent. Regulatory compliance is established under ISO 7405:2018 for dental device biocompatibility, ISO 10993-1:2018, ISO 10993-5:2009, and ISO 10993-10:2010 for sensitization; ethylene oxide sterilization is used under ISO 11135:2014 because autoclaving induces immediate shrinkage, and the sterile barrier is validated under ISO 11607-1:2019. Residual solvent levels must fall below USP <467> limits, with gas chromatography release testing on each batch. Terminal finished forms are rectangular or pre-shaped membranes, pouched dry, at thicknesses of 0.1–0.3 mm. The main production-scale defect is edge wrinkling during solvent evaporation, caused by non-uniform drying rates across the coating web; this is controlled by staged drying zones with graduated temperature and airflow.
Extrusion-based additive manufacturing of patient-specific bone void fillers and craniofacial scaffolds uses RESOMER L 206 S after conversion from pellets into filament of 1.75 mm or 2.85 mm diameter on a single-screw filament extruder with a 20:1 L/D ratio, a 20 °C water bath, and online laser diameter measurement to maintain ±0.05 mm tolerance. In composite scaffolds, 10–20 wt% hydroxyapatite or β-tricalcium phosphate is dispersed before filament extrusion; ceramic loadings above 25 wt% produce filament brittleness and nozzle clogging. Printing uses nozzle temperatures of 195–210 °C, a build plate at 60–80 °C, layer heights of 100–200 µm, and print speeds of 20–40 mm/s; printed scaffolds are annealed at 100 °C under vacuum for 4 h to increase crystallinity and reduce residual stress. Mechanical testing of printed coupons follows ISO 527-2:2012 for tensile modulus and ISO 604:2002 for compressive strength; regulatory pathways require ISO 13485:2016, ISO 10993-1:2018, ISO 10993-5:2009, and ISO 10993-6:2016, together with regional patient-specific device technical documentation under MDR 2017/745 Annex XIII where applicable. Finished product types include sterile patient-specific scaffolds for orbital floor reconstruction, alveolar ridge augmentation, and non-load-bearing bone void filling. The key process limitation is layer fusion consistency: temperatures below 195 °C lead to delamination, while temperatures above 210 °C reduce molecular weight and cause viscosity drift; therefore nozzle melt temperature and pressure are logged on every build.
Micronized ester-terminated poly(L-lactide) of the RESOMER L 206 S grade is used in sterile injectable formulations for soft-tissue augmentation. The polymer is cryogenically milled and sieved to a D50 of 40–80 µm and suspended in a carboxymethylcellulose and mannitol carrier at 30–50 mg/mL before lyophilization; the dried cake is reconstituted with water for injection and injected through a 26G or 27G needle. Sterility is established by ethylene oxide under ISO 11135:2014 or by gamma irradiation at validated doses determined under ISO 11137-1:2006/Amd 1:2013, with verification dose auditing to ensure no measurable loss in inherent viscosity. Biocompatibility evaluation follows ISO 10993-1:2018, ISO 10993-5:2009, ISO 10993-10:2010, and ISO 10993-11:2017; sterility and endotoxin limits are controlled under USP <71> and USP <85>. Particle-size analysis is repeated after sterilization and after reconstitution according to ISO 13320:2020, with a D90 limit of 150 µm to prevent injection blockage; agglomeration during terminal sterilization is the main batch-rejection mode. The terminal product is a sterile injectable implant for correction of facial lipoatrophy and moderate wrinkles. Because the polymer degrades slowly via hydrolysis into lactic acid, the treatment volume effect is delayed by several weeks, which must be reflected in clinical use documentation.
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RESOMER L 206 S is supplied as an ester-terminated poly(L-lactide) of medical grade, with the designation identifying a homopolymer of L-lactide and a nominal inherent viscosity of 0.8–1.2 dL/g measured as a 0.1% w/v solution in chloroform at 25°C. The ester-terminated architecture caps terminal chain units with non-acidic ester groups, reducing the initial population of free carboxylic acid end groups relative to acid-terminated poly(L-lactide). Production is managed under a quality system registered to ISO 13485:2016. The neat resin is not a finished medical device; conformance with ISO 10993-1:2018 must be established on the sterilized finished device and not on the granulate alone.
The grade is delivered as white to pale yellow granules with low moisture content when sealed, but exposure to ambient air at relative humidity above 60% requires reconditioning before melt processing. The certificate of analysis should be checked against the release specification matrix below; a lot falling near the lower IV bound may not provide the same melt strength as a lot near the upper bound in high-draw monofilament spinning.
| Parameter | Reference method | Limit |
|---|---|---|
| Inherent viscosity | 0.1% w/v in chloroform, 25°C | 0.8–1.2 dL/g |
| Residual lactide monomer | Gas chromatography | < 0.5 wt% |
| Residual solvents | Headspace gas chromatography | < 0.1 wt% |
| Water content | Karl Fischer titration | < 0.5 wt% |
| Heavy metals | ICP-OES after digestion | < 10 ppm |
| Sulfated ash | Ph. Eur. 2.4.14 | < 0.1 wt% |
| Appearance | Visual inspection | White to pale yellow granules |
Melt processing of poly(L-lactide) is constrained by the separation between the crystalline melting endotherm and the onset of rapid thermal chain scission. Differential scanning calorimetry according to ASTM D3418-21 on dried granulate typically shows a glass transition near 60°C and a melting event in the 170–190°C range; measurable degradation accelerates above 230°C under prolonged melt residence. Barrel settings are therefore operated at 180–210°C for most single-screw and twin-screw configurations, keeping the melt temperature above the crystalline melting point but below the threshold at which lactide reformation, discoloration, and viscosity collapse become rapid.
On a 25 mm co-rotating twin-screw extruder with an L/D ratio of 40:1, the screw profile should limit high-shear kneading blocks that generate excessive viscous heating. Residence times greater than 8 min or melt pressure spikes above 120 bar are associated with measurable molecular weight loss and batch-to-batch drift. In-line melt pressure transducers and torque recorders should be sampled at 1 Hz during validation runs; a downward torque trend without a corresponding screw speed change indicates polymer degradation rather than a feed disturbance.
Injection moulding of RESOMER L 206 S for resorbable fixation pins or small plates uses clamp forces above 500 kN, mould temperatures of 20–40°C, and fill speeds of 15–60 mm/s depending on part thickness. The low melt viscosity in the 0.8–1.2 dL/g IV corridor permits filling of 0.5 mm thin-wall sections, but packing time must be brief because the gate freezes rapidly in cold runners. Tensile specimens conditioned at 23°C and 50% RH should be tested according to ISO 527-1:2019; the measured tensile modulus is sensitive to the degree of crystallinity induced by the mould-cooling profile. Post-mould annealing at 80–100°C for 2–6 h under vacuum raises crystalline content and may reduce early creep in oriented implant shafts, but it also modifies the subsequent degradation rate.
Because the product is specified by inherent viscosity rather than by a single molecular weight average, batch acceptance is a range. A lot near 0.8 dL/g will display lower shear viscosity, lower melt pressure at constant screw speed, and faster initial hydrolytic degradation relative to a lot near 1.2 dL/g, which may require higher melt temperature or reduced screw speed to maintain equivalent flow. The practical consequence for hot-runner injection moulds is that filling-to-packing switchover points calibrated on one lot cannot be transferred to another without verifying melt viscosity.
Capillary rheometry according to ISO 1133-1:2022 may be used to generate a melt volume-flow rate for incoming lots, but single-point flow measurements do not capture the shear-thinning envelope. Apparent shear viscosity scans between 100 s⁻¹ and 1000 s⁻¹ at the intended melt temperature, recorded on a capillary rheometer with a 1.0 mm die and entrance-angle correction, provide a more useful comparison. The resulting shear-thinning exponent can be used to set extrusion barrel profiles and to detect abnormal lots that fall within the IV specification but differ in molecular weight distribution.
Hydrolytic degradation of ester-terminated PLLA proceeds by random main-chain ester-bond scission. In an acid-terminated PLLA of equivalent IV, terminal carboxylic acid groups can catalyze hydrolysis in the immediate local environment; ester capping reduces this initial concentration of acid end groups and delays the onset of autocatalytic core degradation. In vitro degradation studies should follow ISO 13781:2017 in buffered media at 37°C with a mass-to-buffer ratio defined by the intended implant surface area. Samples thicker than 1.0 mm often show central hollowing or white discoloration before complete mass loss because acidic oligomers diffuse more slowly from the core than from the surface. This spatial degradation pattern is not a product defect and must be included in design verification of bulk-degrading absorbable implants.
Moisture is the principal process variable that converts a stable granulate into low-viscosity material during melting. Poly(L-lactide) is highly sensitive to hydrolytic chain scission at processing temperatures; if the Karl Fischer water content exceeds 250 ppm immediately before melt entry, the resulting molecular weight loss can be detected as a drop in die pressure and a rise in residual lactide monomer. Pre-drying in a desiccant dryer at 80°C for 4 h with a dew point no higher than -40°C is a common starting point; vacuum drying at 80°C under 30 mbar is used for smaller batches. After drying, transfer under dry nitrogen or dry air, and limit open hopper residence to 30 min at ambient humidity above 60%.
Laboratory water content should be confirmed by Karl Fischer titration using ISO 15512:2019 on a sample taken from the hopper throat, not from the original sealed bag. If the measured value exceeds 250 ppm, re-drying is required. Dry heat and high shear do not correct moisture-induced damage; they may mask the resulting viscosity loss until dimensional or mechanical failures appear downstream.
Compared with acid-terminated PLLAs of similar molecular weight, RESOMER L 206 S offers a lower initial concentration of carboxylic acid chain ends and therefore a reduced tendency to autocatalyze during early hydration. This is relevant in drug-matrix prototypes where a low initial acid environment is desired to protect acid-sensitive active ingredients. The grade is not inherently resistant to aminolysis; contact with primary or secondary amines in solution or melt can cleave main-chain ester bonds and should be avoided. Ethylene oxide sterilization is generally considered less damaging to PLLA than gamma irradiation, but residual ethylene oxide limits must be validated according to ISO 10993-7:2008. Gamma irradiation at a nominal 25 kGy will reduce molecular weight and should be accompanied by post-irradiation inherent viscosity measurement to establish lot-specific acceptance criteria.
The ester-terminated poly(L-lactide) backbone distinguishes RESOMER L 206 S from amorphous PLGA copolymers such as RESOMER RG 504 H, which degrade faster owing to glycolic acid units and lack a crystalline melting plateau. It also differs from acid-terminated PLLA grades of similar inherent viscosity principally in early degradation kinetics rather than in glass transition or melting temperature. Compared with higher-IV RESOMER L 210 S, RESOMER L 206 S has lower melt viscosity and is generally selected for thinner injection-moulded components; however, no direct substitution should be made without comparative in vitro degradation data generated under ISO 13781:2017, because final resorption time is determined by device wall thickness, crystallinity, sterilization, and implantation site as much as by resin IV alone. Published data for identical device geometries across all relevant grade permutations is limited; proprietary design packages should therefore be qualified on the specific lot range rather than on published resin-level comparisons.
For solvent-based processing such as microsphere formation or film casting, RESOMER L 206 S is soluble in dichloromethane, chloroform, and tetrahydrofuran, but solution viscosity and evaporation rate must be controlled because PLLA crystallizes during slow solvent removal. Residual solvent limits follow ICH Q3C for pharmaceutical applications. Membrane filtration of the polymer solution before casting is common, but filtration pressure should be monitored because high-molecular-weight fractions can raise solution viscosity within the 0.8–1.2 dL/g IV band. Ester termination does not eliminate hydrolytic degradation of the dissolved polymer in water-miscible solvents; solutions should be processed promptly and stored cold under desiccated conditions.
