Luminy PLA LX575 is a high-heat, high-flow injection-moulding grade of polylactic acid supplied by TotalEnergies Corbion. The resin is produced as cylindrical pellets and is formulated around a poly(L-lactic acid) backbone with a nucleating package that shortens crystallization time in heated tooling. This formulation boundary immediately separates LX575 from transparent amorphous PLA grades, which retain optical clarity but soften near the PLA glass-transition range. The grade is intended for non-refrigerated food-contact articles, single-serve beverage capsules, rigid food-service cutlery, cosmetic packaging, and technical housings that require dimensional stability above ambient service temperatures. Density is specified as 1.24 g/cm³ under ISO 1183-1, while melt flow is determined under ISO 1133-1 at 210 °C with 2.16 kg. The supplier’s moisture specification requires residual pellet moisture below 250 ppm before melt processing, a limit that reflects the hydrolytic sensitivity of poly(L-lactic acid) rather than a conventional polyolefin drying target.

Thermal and Rheological Profile of LX575 in Injection-Moulding Operations

The melt mass-flow rate reported for LX575 lies in the 15–35 g/10 min range at 210 °C and 2.16 kg under ISO 1133-1:2022, placing the grade in the high-flow segment of heat-resistant PLA. The recommended melt temperature window is 200–220 °C; below 200 °C, viscosity rises and thin-wall filling below 1 mm becomes pressure-limited, while above 220 °C lactide formation and chain scission begin to alter melt consistency. A typical barrel zone profile on a 24:1 L/D single screw is 180–195–205–210–215 °C, with nozzle temperature set at 215–220 °C. Because the crystallization half-time passes through a minimum near 105–110 °C, the moveable and fixed mould halves are normally held at 90–110 °C to develop crystallinity before ejection. At this wall temperature, cooling time for a 2 mm side wall is 12–20 s; a 4 mm rib or boss can require 30–45 s, which is the central cycle-time constraint for this resin.

Modulated differential scanning calorimetry for LX575-class high-heat PLA shows the amorphous glass-transition onset near 55–60 °C, a cold-crystallization exotherm between 100 °C and 110 °C, and a melting endotherm between 170 °C and 180 °C when heated at 10 °C/min. This thermal signature explains why the mould wall must sit near the cold-crystallization maximum to develop crystallinity before ejection. If the tool extracts heat too quickly, the polymer chain segments have insufficient mobility for nucleation and the part leaves the mould below its maximum crystalline fraction. Annealing can be used to correct this condition, but only when the part is fixtured or when the dimensional change is acceptable.

Capillary rheometry at 210 °C shows shear-thinning behaviour typical of high-flow PLA: apparent viscosity decreases from roughly 250–400 Pa·s at 100 s⁻¹ to below 80 Pa·s at 1,000 s⁻¹. This response permits filling of thin ribs and long flow paths without excessive cavity pressure, but it also means that variations in injection speed during fill can produce surface flow marks. For LX575, fill speed should be profiled rather than left at a single setting; a fast initial fill of 60–80 mm/s ram speed reduces premature freeze-off at the gate, while a reduced final fill speed prevents jetting and gate turbulence.

Injection pressure in heated tools is generally 800–1,000 bar, but hot-runner pressure drop can add 150–250 bar depending on gate diameter and nozzle length. If the mould is run below 80 °C, LX575 remains substantially amorphous and the heat-deflection benefit is lost; if the mould exceeds 120 °C, ejection becomes difficult because the part surface is insufficiently rigid at demoulding. The practical thermal window is therefore narrow. Batch-to-batch variation in melt flow should be checked under ISO 1133-1 because regrind levels above 20 wt% can lower melt viscosity through molecular-weight reduction, leading to flash in tools sized for virgin material. Production equipment with check-ring clearances worn beyond 0.10 mm may show inconsistent shot weights because the high-flow formulation magnifies backflow during injection hold.

How Does LX575 Differ from Transparent Amorphous PLA Grades?

The principal difference is crystallization behaviour rather than chemical origin. Transparent amorphous injection PLA develops negligible crystallinity under rapid cooling, and its heat deflection temperature at 0.45 MPa remains near 55–60 °C under ISO 75-2. LX575 parts moulded at a wall temperature of 100 °C and annealed in the tool are reported to reach 85–95 °C at the same load. This shift is comparable to polypropylene homopolymer but is achieved without blending with petroleum-based comonomers. The trade-off is optical: the nucleating system creates internal haze, so LX575 is not a direct replacement for transparent PLA in applications requiring through-wall clarity.

Melt-flow position also differs. LX575 retains a higher melt mass-flow rate than low-flow high-heat PLA extrusion grades, a property that supports thin-wall injection moulding. Mechanical rigidity remains close to unfilled PLA, with tensile modulus reported in the 3.2–3.6 GPa range under ISO 527-2, but failure strain is below 5%. Therefore LX575 should not be compared with impact-modified PLA compounds where notched impact strength is the primary design criterion. Instead, the selection logic is heat resistance plus flow for rigid packaging and small technical parts.

Comparison with Luminy L105, a transparent amorphous injection grade, shows the selection boundary. L105 remains transparent and is processed in cold moulds at 20–40 °C, but its HDT B under 0.45 MPa is below 60 °C unless post-annealed. LX575 requires mould temperatures near 100 °C and accepts the resulting haze. The two grades are therefore not interchangeable on the same tool without altering cooling circuits, ejection timing, and dimensional allowances. That distinction is more important than the raw mechanical values, because tensile modulus and notched impact are close between unfilled amorphous and high-heat PLA; heat resistance and crystallization management define the material choice.

At a plant with desiccant dryers sized for 100 kg/h throughput, pellets are dried at 80 °C for 4 h with a supply-air dew point of -40 °C. Hopper residence above 2 h in an unconditioned room at 30 °C and 70% RH can reintroduce surface moisture; this is a common source of gate splay in hot-runner tools. The dryer return-air dew point should be verified at shift start because saturated desiccant beds allow wet pellets to pass the hopper while still above 300 ppm moisture. A dew-point probe at the hopper inlet, not only at the dryer outlet, is therefore required when LX575 is moulded in coastal or high-humidity plants. Conveying with uninsulated stainless lines longer than 15 m can allow pellet cooling and condensation; a line temperature of 60–70 °C prevents condensation. These are operational constraints observed on injection lines rather than laboratory drying curves.

When Annealing in a Heated Mould Is Removed from the Cycle

If the mould cannot be held at 90 °C or higher, the part cools in the amorphous state and the heat-deflection temperature remains below 65 °C at 0.45 MPa. Post-mould oven annealing at 100 °C for 15 min can restore crystallinity, but unconstrained shrinkage in thin walls can exceed 1.0%, which is unacceptable for lids, capsule rims, and interlocking features. For this reason LX575 is not recommended for tools designed for cold-water moulding of amorphous PLA. When a hot mould is used, temperature uniformity is more important than average temperature: a difference of more than 5 °C between fixed and moving halves produces asymmetric crystallization and measurable warpage on flat parts longer than 50 mm. Warpage in an unconstrained lid moulded at 100 °C has been recorded at 0.6–0.9 mm across a 50 mm span when the moving half was 6 °C cooler. Published data for this specific configuration is limited, and control limits should be validated on the target tool.

Single-serve beverage capsules are a representative application because the lid rim must withstand hot-water contact near 100 °C and the side wall must fill below 0.7 mm without excessive clamp force. In such tools, melt temperature of 215 °C, mould temperature of 100 °C, and hold pressure of 600–800 bar are used; dimensional tolerance of ±0.05 mm on the rim diameter is achievable only after 20–30 cycles of thermal stabilization. Food-service cutlery and small appliance housings are moulded under similar conditions, but thick sections above 3 mm require longer cooling and are generally avoided because crystallinity develops unevenly through the wall. Hot-runner valve gates should be selected with independent tip temperature control because thermal degradation at the gate is the primary source of black specks when cycle interruptions exceed 5 min.

Shrinkage of LX575 in a hot mould is anisotropic: machine-direction shrinkage can be 0.4–0.6%, while transverse shrinkage can reach 0.8–1.0% depending on flow orientation and crystallinity. Cavity dimensions must therefore be compensated differently from amorphous PLA, which usually shows lower isotropic shrinkage in cold tools. Mould designers often add 0.5–1.0° draft because crystalline parts are harder and can resist ejection from deep ribs. Ejector pins should be placed on the centre stiffness lines, and ribs should maintain a base thickness of 50–60% of the adjoining wall to prevent sink marks without increasing cooling time beyond the limits described above.

Compliance, Food-Contact, and Storage Boundaries

LX575 can be used in food-contact applications only when the converted part meets the applicable regulatory migration limits for the intended food type and temperature. Under European Commission Regulation (EU) 10/2011, overall migration testing is performed on the finished article; a typical acceptance threshold is 10 mg/dm² for food-contact plastics, but specific migration limits for lactic acid and any nucleating-agent residues must be confirmed against the grade’s statement of compliance. For the United States, the applicable status is determined under FDA 21 CFR; the manufacturer should supply a food-contact statement for LX575, and the converter must verify that the formulation is cleared for the intended article type and use conditions. The raw polymer is not automatically a food-contact approved finished component.

Regrind use is limited by the contamination risk from non-PLA materials, not by an absolute processing ceiling. Closed-loop regrind at 20 wt% is common, but in food-contact testing the finished part must include any regrind content that will be sold. Storage conditions should maintain bags sealed below 35 °C and below 60% RH. Open bags should be consumed within 8 h in humid plants or returned to dry storage. The material should not be dried with polycarbonate or polyamide in shared dryers because residual moisture targets and melt-phase degradation products differ.

Incompatibility with halogenated polymers is operationally significant. Co-moulding or purging against PVC residues is to be avoided because hydrochloric acid formed at melt temperature catalyses PLA chain scission; this accelerates MFR drift and can cause visible surface degradation at processing temperatures as low as 190 °C. Purging should be performed with a dedicated PLA purge or low-viscosity polyethylene for at least 2 barrel capacities before shutdown.

Storage of LX575 in silos for large-volume moulding operations requires dry-air purge and hopper loader desiccant beds. A silo at 40 °C and 80% RH can be used only if the material is conveyed immediately to desiccant drying; extended storage above 30 °C increases pellet blocking and moisture uptake. The supplier’s lot-specific datasheet should be consulted before changing the nucleating package or adding colour concentrates because iron oxide pigments and certain organic colorants can shift crystallization onset and alter mould release. Published data for this specific configuration is limited; therefore, pigment-compatibility trials on the production tool are required.