| HS Code | 686628 |
| Product Name | PURASORB PLG 8523 Medical Device Lactide-Glycolide Copolymer |
| Chemical Name | Poly(L-lactide-co-glycolide) |
| Monomer Ratio | 85:15 L-lactide:glycolide (mol/mol) |
| Copolymer Structure | Random copolymer |
| Inherent Viscosity | 2.3 dL/g (chloroform, 25 °C) |
| Appearance | White to off-white pellets or granules |
| Glass Transition Temperature | Approximately 55 °C |
| Density | Approximately 1.2 g/cm³ |
| Solubility | Soluble in chloroform, dichloromethane, dioxane, and hexafluoroisopropanol; insoluble in water and alcohols |
| Degradation Time | Approximately 5 to 6 months |
| Residual Monomer Content | Typically less than 0.5% |
| Water Content | Typically less than 0.5% |
| Heavy Metals | Typically less than 10 ppm |
| Storage Conditions | Store at -20 °C, protected from moisture |
As an accredited PURASORB PLG 8523 Medical Device Lactide-Glycolide Copolymer factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | PURASORB PLG 8523 Medical Device Lactide-Glycolide Copolymer is packaged in 25 kg fiber drums with double polyethylene liners. |
| Container Loading (20′ FCL) | 20′ FCL container loading for PURASORB PLG 8523 Medical Device Lactide-Glycolide Copolymer: palletized, dry, sealed, and shipped under controlled conditions. |
| Shipping | PURASORB PLG 8523 is typically shipped in sealed, moisture-barrier packaging, often under inert atmosphere, at ambient or refrigerated conditions per supplier specifications. It is not classified as dangerous goods for transport. Store cool, dry, and protected from heat, moisture, and light; follow all label and SDS requirements. |
| Storage | Store PURASORB PLG 8523 in a tightly sealed, moisture-proof container under cool, dry, well-ventilated conditions. Refrigerate at 2–8°C, protected from light, heat, and moisture. Use an inert atmosphere for extended storage. Handle in a low-humidity environment; allow packages to equilibrate before opening to avoid condensation. Keep away from incompatible materials and ignition sources. Follow the manufacturer’s SDS and expiration date. |
| Shelf Life | Typically 24 months when stored unopened in original packaging at -20°C, protected from moisture and heat per manufacturer recommendations. |
Before PLG 8523 pellets enter the injection barrel, they are dried under vacuum at 80 °C for 6–10 h to a moisture level below 150 ppm. An all-electric injection moulding machine with a clamp force between 600 kN and 1,200 kN is selected for small orthopaedic screws. The plasticising screw uses an L/D ratio of 22:1 and a non-return ring with a clearance below 0.05 mm. Barrel zones are profiled from 175 °C at the feed zone to 205 °C at the nozzle. The mould is cooled with water at 20 °C to 30 °C. Injection speed is set between 20 mm/s and 50 mm/s. Back pressure is held between 5 bar and 10 bar to minimise shear heating without sacrificing melt homogeneity. Screw rotation speed is limited to 80–120 rpm. A direct hot-tip gate with a diameter of 0.8 mm is used to reduce pressure loss into the cavity. Cycle time is typically 25–40 s depending on part mass. Packing pressure is set at 70–80% of peak injection pressure for 2–4 s. The terminal product is an interference screw for anterior cruciate ligament reconstruction. After moulding, parts are kept in moisture-barrier packaging with desiccant until terminal sterilisation. Ethylene oxide processing is used where permitted by the device design. The narrow processing window is dictated by the absence of a crystalline melt: the material flows as an amorphous high-viscosity mass above its glass transition, and local barrel temperatures above 210 °C produce rapid molar mass reduction. Each lot is subjected to inherent viscosity testing according to ISO 1628-1 and biological evaluation according to ISO 10993-1, ISO 10993-5, and ISO 10993-6. Process capability studies on cavity pressure sensors are used to reject short shots and sink marks. Published data for this specific grade in ACL screw geometry are limited, but the processing boundaries above are consistent with high-molar-mass lactide-rich PLGA industrial practice.
| Evaluation endpoint | Test method | Condition / measured property |
|---|---|---|
| Residual moisture before processing | Karl Fischer titration or equivalent | Below 200 ppm for extrusion, below 150 ppm for injection moulding |
| Cytotoxicity | ISO 10993-5 | Elution method, cell viability threshold per standard |
| Local effects after implantation | ISO 10993-6 | Histopathology at 4 and 12 weeks |
| Hypersensitivity and irritation | ISO 10993-10 | Extract injection, skin scoring per standard |
| In vitro degradation | ASTM F1635-16 | Phosphate-buffered saline, 37 °C, pH 7.4 |
| In vitro degradation of lactide/glycolide implants | ISO 13781:2017 | Degradation product characterisation |
| Thermal transitions | ISO 11357-2 | DSC heating rate 10 °C/min under nitrogen |
A braided suture anchor body requires two separate PLG 8523 process streams if a fully resorbable anchor is specified. The first stream is injection moulding of an anchor body with a through-hole for suture loading. The second stream is predrying and micro-injection moulding of a separate eyelet or cap. No plasticiser is added. If radiopacity is not required, the copolymer is used neat. A micro-injection moulding machine with a clamp force of 80–150 kN and a screw diameter of 14 mm is selected. Barrel temperature is kept at 180–200 °C. The mould temperature is set at 25 °C. Injection speed is reduced to 15–30 mm/s because the thin walls of the eyelet are prone to shear heating. The anchor body is allowed to cool for 20 s before ejection. Sharp edges at the suture hole are radiused to a minimum of 0.2 mm to prevent suture cutting. The fully resorbable anchor is intended for rotator cuff repair and labral repair. Because the copolymer is amorphous, it does not produce the crystalline fragment wear debris sometimes observed with semi-crystalline PLLA anchors. However, the same amorphous structure reduces stiffness compared with uniaxial PLLA. Device designers compensate with thicker load-bearing ribs rather than higher packing pressure. Sterile packaging follows ISO 13485 quality management requirements. Biological safety data cover ISO 10993-5 and ISO 10993-10. Hydrolytic degradation is evaluated by ASTM F1635-16. Processing lots that exceed 210 °C in any barrel zone are quarantined and tested for inherent viscosity loss greater than 0.1 dL/g against the certificate of analysis value.
Solvent casting of PLG 8523 for barrier membranes begins with polymer dissolution in dichloromethane at a concentration of 6–10 wt%. The solution is filtered through a 0.45 µm polytetrafluoroethylene membrane to remove gel artefacts. A knife coater applies the solution to a polyethylene terephthalate liner with a gap of 200–800 µm, depending on the target dry thickness. Solvent evaporation proceeds at 25 °C for 2 h, followed by 40 °C under vacuum at 0.08 MPa for 4 h. Residual dichloromethane is measured by headspace gas chromatography and must remain below 600 ppm according to ICH Q3C Class 2 limits. The dried film is removed from the liner and die-cut into trapezoidal membranes for guided bone regeneration around dental implants. The terminal barrier membrane must exclude epithelial ingrowth while permitting nutrient diffusion. Because PLG 8523 is amorphous, the film is flexible after plasticisation by water uptake during use, but dry handling requires controlled relative humidity below 30% to prevent blocking. Mechanical characterisation follows ISO 527-3 for thin plastic films, with tensile modulus measured at 23 °C and 50% relative humidity after conditioning for 48 h. Published comparators for lactide-rich PLGA films report tensile modulus between 1 GPa and 3 GPa, but lot-specific measurement is required because residual solvent and thickness influence stiffness. Biological evaluation includes ISO 10993-5 for cytotoxicity, ISO 10993-10 for irritation, and ISO 10993-18 for leachables. Degradation products are characterised under ISO 10993-13. The film should be stored in a desiccated, light-protective pouch because the lactide-rich copolymer is susceptible to moisture-induced hydrolytic pre-degradation if the package seal fails.
When PLG 8523 replaces poly(L-lactide) homopolymer in craniomaxillofacial fixation plates, the manufacturer must recalculate bending stiffness because the copolymer is amorphous and absorbs water more rapidly than PLLA. Plates are compression moulded from pre-dried PLG 8523 granules at 180–200 °C under 10–15 MPa for 3–5 min. The press platens are heated electrically and cooled by water channels at 15–20 °C to quench the sheet. Sheets are machined on a five-axis CNC station using carbide tooling with a cutting speed of 60–100 m/min. Panel thickness is typically 1.2–2.0 mm. Screw holes are drilled to match resorbable screws with major diameters of 1.5 mm or 2.0 mm. The terminal plates are designed for non-load-bearing paediatric craniosynostosis and midface fracture fixation. Because PLG 8523 loses molar mass faster than PLLA homopolymer, the implant retains fixation strength for a shorter period. Designers compensate by increasing the cross-sectional area at the bridge between screw holes rather than relying on a crystalline phase. Biological evaluation follows ISO 10993-6. Degradation is tested under ISO 13781:2017 in buffered media. Mechanical characterisation after immersion in phosphate-buffered saline at 37 °C is used to establish the functional strength-retention window. Plates are not indicated for load-bearing mandibular defects without additional metallic fixation. Ethylene oxide sterilisation is validated to a sterility assurance level of 10−6 in accordance with ISO 11135.
Compounding PLG 8523 with submicron barium sulfate at 10–15 wt% produces a radiopaque compound for absorbable ligating clips that require radiographic visualisation during placement. The compounding step uses a co-rotating twin-screw extruder with an L/D ratio of 40:1 and a screw diameter of 25 mm. Barrel zones are set from 170 °C to 195 °C. The polymer is fed at the main hopper, and the barium sulfate is introduced through a side feeder after the polymer is fully molten. Screw speed is maintained between 200 rpm and 300 rpm. Vacuum devolatilisation at 0.08 MPa is applied in the final barrel zones. The extrudate is strand-pelletised and dried at 80 °C for 8 h. The filled compound is injection moulded into ligating clips with hinge thicknesses between 0.3 mm and 0.5 mm. The small hinge cross-section is the most sensitive feature because excessive shear heating accelerates copolymer chain scission. Mould temperature is held at 25 °C. Gate vestige at the clip hinge is trimmed with scalpel blades to prevent tissue snag. The terminal device is used for occlusion of small vessels during laparoscopic procedures. Radiopacity is assessed according to ASTM F640. Biological evaluation includes ISO 10993-5, ISO 10993-10, and USP Class VI. Shelf-life studies monitor the change in clip closure force under accelerated ageing at 50 °C and 75% relative humidity.
For melt-spun PLG 8523 fibre scaffolds used in soft-tissue augmentation, the drawing step is the main determinant of tensile strength. Single-screw extrusion is used with an L/D ratio of 24:1 and a spinneret containing holes of 0.3–0.6 mm diameter. Melt temperature is held between 195 °C and 215 °C. The extruded filaments pass through a quench chimney with air at 15–20 °C and a flow rate of 0.5 m/s. Initial take-up speed is set to maintain a spinline draw of 2:1. Orientation takes place in a second stage at 60–70 °C, just above the glass transition of the lactide-rich copolymer. A total draw ratio of 3:1 to 5:1 is applied across two heated godets. Attempts to draw below the glass transition produce brittle fracture and no stable molecular orientation. The drawn fibres are knitted or braided into a resorbable surgical mesh for reinforcement of soft tissue repairs. Fibre tensile testing is performed according to ISO 2062 and ASTM D2256 by the single-strand method. Mesh pore dimensions are measured under a calibrated optical microscope at 10× magnification and reported as equivalent circular diameter. Biological evaluation follows ISO 10993-5, ISO 10993-6, and ISO 10993-10. In vitro degradation of the fibre is monitored by ASTM F1635-16. Published data for PLG 8523 specifically in warp-knitted mesh configurations are limited, so process development must include a designed experiment across draw ratio and godet temperature to identify the maximum tenacity without filament breakage.
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PURASORB PLG 8523, a medical device lactide-glycolide copolymer supplied as white to off-white pellets, is specified for absorbable implant components requiring a high-molecular-weight, L-lactide-rich resorbable polyester. The product identifier encodes the nominal L-lactide:glycolide molar ratio of 85:15 and the midpoint inherent viscosity of 2.3 dL/g, determined in chloroform at 0.1% w/v and 25°C using a method aligned with ISO 1628-1:2021. The grade belongs to the high-IV segment of the PURASORB PLG portfolio and is differentiated from lower-IV PLG grades by higher melt strength, slower hydrolytic degradation, and extended strength retention under aqueous conditions. The high L-lactide content reduces water uptake relative to 50:50 PLG copolymers, while the 2.3 dL/g molecular-weight parameter reduces melt flow and shifts the material toward melt processing routes such as injection molding and twin-screw extrusion rather than solvent-based microsphere fabrication.
Typical specification limits are summarized in Table 1.
| Parameter | Typical specification range | Test method |
|---|---|---|
| Inherent viscosity midpoint | 2.3 dL/g midpoint; 2.0–2.6 dL/g acceptance | ISO 1628-1:2021 |
| L-lactide:glycolide molar ratio | 85:15 nominal | 1H NMR or equivalent |
| Residual monomer | <1.0% w/w | GC-FID |
| Water content | <0.5% w/w | ISO 15512:2019 |
| Residual solvent | <0.1% w/w | Headspace GC per ICH Q3C |
| Tin content | ≤200 ppm | ICP-MS |
Residual monomer and water content are critical because lactide and glycolide monomers can accelerate hydrolytic degradation during storage and melt processing. PLG 8523 is packaged in sealed, moisture-barrier pouches under inert gas. The specified water content is maintained below 0.5% by weight; once exposed to ambient air with relative humidity above 60%, the pellet surface adsorbs moisture and may require vacuum drying at 40°C to 45°C for 12–24 h before melt processing. Drying temperatures above 50°C are avoided because the copolymer can sinter in the dryer, and residual monomer can promote chain scission. The residual lactide limit of below 1.0% is monitored by gas chromatography with flame ionisation detection; residual solvent levels are kept below 0.1% according to headspace gas chromatography against ICH Q3C classes. Tin catalyst residues are specified because stannous octoate is used in ring-opening polymerisation; the limit is typically not more than 200 ppm of tin as determined by inductively coupled plasma mass spectrometry after closed-vessel digestion.
On a co-rotating twin-screw extruder with 25:1 to 40:1 length-to-diameter ratio, high-IV PLG 8523 is processed with barrel set points of 170°C to 200°C; the actual melt temperature is measured by an infrared or melt thermocouple because shear heating can raise the melt above the set point. Melt temperatures above 210°C lead to rapid transesterification and molecular-weight loss, while residence times below 5 minutes and screw speeds of 100–200 rpm are used in production-scale trials to limit specific mechanical energy input. Screw configurations with conveying elements and narrow kneading blocks are preferred over high-shear dispersive elements because the high-IV polymer is sensitive to shear-induced chain scission. For injection molding, the material requires a reduced compression ratio screw, a shut-off nozzle, and clamp force appropriate to the part projected area; small implant components are typically molded with clamp forces from 500 kN to 1500 kN. Processing windows are narrower than those for lower-IV PLG grades because the high molecular weight reduces flow and elevates fill pressure. Lot-specific validation is required because these values are typical processing references for high-IV PLG copolymers, not absolute machine settings.
In hydrolytic degradation, ester bond cleavage follows pseudo-first-order kinetics in dilute aqueous media and occurs preferentially in glycolide-rich sequences. The 85:15 backbone reduces the frequency of contiguous glycolide-glycolide dyads, lowering the rate of autocatalytic hydrolysis because fewer hydrophilic oligomers are generated to acidify the interior. At 37°C and pH 7.4, water uptake reaches a plateau before mass loss begins; the induction period depends on initial molecular weight, residual monomer content, and sterilization history. Devices molded from PLG 8523 with residual monomer near the upper specification limit may show faster early mass loss than those with residual monomer below 0.5%. The glass transition temperature for 85:15 PLG is typically in the 55–60°C range; annealing at 60–70°C for 2–4 h can improve dimensional stability but may embrittle thin sections.
Terminal sterilization selection affects molecular weight and mechanical properties. Ethylene oxide exposure under ISO 11135:2014 is commonly evaluated for PLG implants because it can be performed at temperatures below 50°C, reducing thermal degradation. However, ethylene oxide and its residual by-products must be removed by aeration; moisture introduced during humidification can initiate hydrolysis. Gamma sterilization at 25 kGy under ISO 11137-1:2006 reduces molecular weight by chain scission, with the magnitude depending on irradiation temperature and oxygen presence. Electron-beam sterilization may produce greater surface-localized degradation because of higher dose rate. Pre-sterilization inherent viscosity should be at the upper end of the 2.0–2.6 dL/g acceptance range if a measurable post-irradiation reduction in inherent viscosity is anticipated; published data for PLG 8523 under specific radiation conditions is limited and must be generated on the finished device.
Degradation of PLG 8523 in aqueous media proceeds by bulk hydrolysis of ester bonds; the hydrophobic L-lactide-rich backbone limits water ingress relative to 50:50 PLG and 10:90 PLG grades. This shifts the onset of mass loss later and preserves molecular weight longer under simulated physiological conditions of 37°C and pH 7.4 phosphate-buffered saline. Comparative data for this exact grade under ISO 13781 are limited in published literature; however, 85:15 PLG copolymers with inherent viscosities near 2.3 dL/g are selected for load-bearing implants where strength retention over several months is required. By contrast, 50:50 PLG grades with lower inherent viscosity degrade faster and are more often processed by solvent casting or microsphere formation. The higher molecular weight of PLG 8523 also reduces solubility in common solvents such as ethyl acetate or acetone, whereas lower-IV PLG grades dissolve readily; chloroform, dichloromethane, and hexafluoroisopropanol are typical solvents for analytical viscosity measurement. PLG 8523 is not interchangeable with lower-IV PLG for microsphere encapsulation or electrospinning, where lower solution viscosity is required.
The polymer is manufactured under a quality system certified to EN ISO 13485:2016; the final medical device requires its own biological evaluation according to ISO 10993-1:2018 and appropriate parts of the ISO 10993 series. Raw-polymer testing typically covers residual solvents according to ICH Q3C, elemental impurities according to ICH Q3D, and residual monomers by gas chromatography. Devices made from PLG 8523 may be sterilized by ethylene oxide under ISO 11135:2014 or by ionizing radiation under ISO 11137-1:2006 after validation. The product should be stored in its original sealed packaging at -20°C or below; excursions to ambient temperature should be limited, and packages should be equilibrated to ambient temperature inside the sealed pouch before opening to prevent condensation.
Table 2. Regulatory and testing checklist
| Requirement | Applicable standard or guideline |
|---|---|
| Quality management system for polymer manufacture | EN ISO 13485:2016 |
| Inherent viscosity | ISO 1628-1:2021 |
| Water content | ISO 15512:2019 |
| Biological evaluation of finished device | ISO 10993-1:2018 |
| Sterilization validation | ISO 11135:2014 / ISO 11137-1:2006 |
| Residual solvents | ICH Q3C |
| Elemental impurities | ICH Q3D |
In a high-humidity production environment, transfer lines between dryer and hopper are often purged with dry nitrogen at a dew point below -40°C because moisture uptake is rapid. Material dried to below 250 ppm residual moisture can re-humidify within 15–30 minutes when exposed to 60% relative humidity at 23°C; therefore, open handling time is limited and the hopper should be blanketed. Avoid contact with nucleophilic additives such as primary amines, which accelerate ester bond cleavage, and avoid storage in unlined containers that may contribute metal residues. Once opened, the material should be processed promptly; if not consumed, residual material should be resealed under inert atmosphere and returned to frozen storage to preserve the specified inherent viscosity.
