Poly(lactic acid) grade REVODE290 enters thin-wall injection moulding of cutlery, lids, and single-serve food-contact articles only after predrying in a desiccant dryer delivering dew point at or below -40 °C. A hopper residence of 4 h at 80 °C is normally required to bring surface moisture below 250 ppm, because melt-phase hydrolysis at 190–220 °C reduces molecular weight sufficiently to cause brittle ejection, gate-stringing, and screw-recovery torque drift. On a reciprocating screw machine with 20:1 to 24:1 L/D and compression ratio between 2.0:1 and 2.5:1, barrel settings are profiled from 165 °C at the feed throat to 210 °C at the nozzle, with hot-runner manifolds held at 200–210 °C; reverse-taper nozzles are preferred to reduce drool. Mould temperature is maintained at 25–60 °C for fast-setting amorphous parts, though temperatures near 60 °C may reduce moulded-in stress while extending cycle time by 15–30%. Injection velocity is set in the 80–150 mm/s range for wall sections of 1.2–2.5 mm, and holding pressure is commonly 50–80 MPa hydraulic with decay over 2–4 s. Published comparative data for PLA of similar D-lactide content indicate tensile yield strength of 55–65 MPa when tested to ASTM D638-14, flexural modulus of 3200–3600 MPa to ISO 178:2019, and notched Izod impact in the range 2.5–3.5 kJ/m² to ISO 180:2019. These values support short-term cold-food service, but heat deflection temperature measured at 0.45 MPa to ASTM D648-16 typically remains 55–60 °C for unreinforced amorphous mouldings, which excludes dishwasher and hot-fill applications. Food-contact suitability must be assessed under Commission Regulation (EU) No 10/2011 using overall migration by EN 1186 and under any applicable supplier food-contact status letter for FDA-compliant articles; the processor is responsible for verifying that regrind ratio, colourant, and nucleating agent do not alter specific migration of lactide.

Why Does PLA Filament Dimensional Tolerance Dictate Spool-to-Nozzle Feeding?

In fused filament fabrication feedstock production, REVODE290 is dried to ≤ 250 ppm residual moisture and processed on single-screw extruders with 25–45 mm screw diameter and 24:1 to 30:1 L/D. A vacuum vent is fitted at barrel zone 6 and a gear pump is placed after the screen changer, because the melt viscosity of PLA at 210 °C is sufficiently shear-sensitive that small screw-speed deviations become filament diameter drift. Processors validate melt rheology with capillary testing to ISO 11443:2021; typical PLA melts exhibit shear viscosities between 500 Pa·s and 2000 Pa·s at 100 s⁻¹, but grade-specific data for REVODE290 should be generated because D-lactide content shifts the viscoelastic curve. Extruder zones are set from 170 °C to 205 °C, die temperature at 190–200 °C, and the melt pump is used to hold output variation below 2%; without positive melt pump control, spooled filament can drift outside 1.75 ± 0.05 mm or 2.85 ± 0.05 mm tolerance, causing under-extrusion or Bowden-tube jams. Water-bath temperatures of 40–60 °C and air-wipe gaps of 3–5 mm are used to maintain ovality below 0.05 mm. At the printer, nozzle temperatures are held at 200–230 °C and heated-bed temperatures at 55–70 °C; PLA does not require a heated chamber, but draught-free ambient air below 30 °C reduces warping. Comparative published data for annealed PLA printed test coupons indicate XY-plane tensile strength of 45–55 MPa to ASTM D638-14, while interlayer tensile strength in the Z-axis can remain 30–50% lower because polymer diffusion across layers is limited by the glass transition. Dimensional stability is temporary; parts left above 50 °C may creep, and annealing at 80–100 °C for 30–60 min can raise the 0.45 MPa HDT to 80–95 °C but introduces anisotropic shrinkage of 0.3–1.5%. Moisture-conditioned spool stock must be re-dried at 60–80 °C for 4–6 h under sealed dry-air flow; hydrolysis from ambient moisture above 60% RH can reduce filament strength within days.

REVODE290 is evaluated in thermoformed bakery and ready-meal trays only as a blend component, because the base grade is not designed as a high-melt-strength sheet resin. When a twin-screw compounder with downstream sheet die is used, PLA pellets are first dried to ≤ 250 ppm moisture and melt-compounded at 180–200 °C with 2–8 wt% impact modifier or chain extender; side-feeding of talc or mineral nucleant at 0.5–2 wt% is used only where faster crystallisation is required. The extruded sheet is passed through a polished roll stack at 40–60 °C, with thickness variation held below 2% by automatic gauge control. During plug-assist thermoforming, the sheet core is brought to 95–115 °C by IR heating, the syntactic foam or PPS plug is maintained at 100–110 °C, and the mould runs at 30–60 °C. Forming air pressure is typically 4–6 bar, and total cycle time for 0.5–1.0 mm sheet ranges from 5 s to 10 s. Published data for amorphous PLA sheet place tensile yield strength at 50–65 MPa to ISO 527-2:2012 and strain at break below 6%; after forming, residual internal stress can reduce puncture resistance, so offline gauging and post-forming annealing at 60–80 °C are used to stabilise dimensions. These trays are suitable for refrigerated and ambient dry bakery goods; they are not appropriate for hot fill or retort use because the 0.45 MPa HDT of unannealed PLA remains 55–60 °C. Compliance testing under EU 10/2011 and EN 1186 is required for direct food contact, and migration of additives from the impact modifier must be declared. Independent industrial case studies for REVODE290 in thermoforming are scarce; published data for this specific configuration is limited, so sheet converters maintain pilot-line verification before scale-up.

When Closure Torque Retention Above Typical Amorphous PLA Limits Is Required

When closure torque retention above typical amorphous PLA limits is required, processing strategy moves from cold-mould amorphous filling to hot-mould crystallisation. REVODE290 is dried as in injection moulding and injected at melt temperatures of 190–215 °C, but the mould temperature is raised to 80–110 °C and the cooling time is extended by 30–80% relative to cold-mould amorphous parts. Crystallisation at the higher mould temperature increases the 0.45 MPa HDT to 85–100 °C to ASTM D648-16 and reduces the tendency of threads to deform under sustained closure load. Torque retention is measured with a digital torque meter at 10 rpm; unannealed amorphous PLA closures commonly fall below 20 N·cm before visible stress whitening, whereas hot-mould crystallised parts can sustain application torques above 45 N·cm when thread thickness exceeds 1.0 mm. Dimensional tolerance on the closure inner diameter must be held within ±0.05 mm to maintain seal engagement with PET or PP bottles; this demands stable mould temperature control of ±2 °C and packing-pressure control within ±5 bar. Surface finishing by pad printing or hot stamping requires surface energy treatment; untreated PLA surfaces often measure 38–42 mN/m when tested with test inks to ISO 8296:2003, and corona or plasma treatment raises this to 50–56 mN/m. Formulators must avoid ester and ketone-based cleaning agents, fragrances with high limonene or terpene content, and continuous alcohol contact, because solvent-induced crazing can generate microcracks at moulded-in gate regions. Compliance for cosmetic packaging is assessed under EU 1223/2009 for safety, while migration of package constituents into the cosmetic formulation may be screened by EU 10/2011 methods; however REVODE290 is not a medical-grade or drug-contact material unless specifically confirmed by the supplier for those applications.

Direct injection moulding of REVODE290 into compostable coffee capsule bodies requires a nucleated, impact-modified formulation because the dry amorphous grade alone has insufficient heat resistance and oxygen barrier for pressurised hot-water extraction. A masterbatch of nucleating agent and 5–20 wt% mineral or cellulosic fibre is compounded before injection; the barrel is set at 180–205 °C, and the hot runner is maintained at 195–205 °C. Mould temperature is held at 90–120 °C to develop crystallinity, and the part cooling time may reach 12–25 s for a wall thickness of 0.3–0.5 mm. Dimensional tolerances around the sealing flange are held at ±0.03 mm to prevent lidding-film peel failures. Compostability certification must follow EN 13432:2000 or ASTM D6400-19, but the selected nucleating agent and filler must themselves meet disintegration and ecotoxicity requirements; heavy-metal limits in the final package are screened by EN 13432:2000 Annex A. The capsule material offers no high-barrier function: published oxygen transmission rates for neat PLA to ASTM D3985-17 are roughly an order of magnitude higher than PET and more than 10× higher than EVOH, so shelf-life extension requires a secondary barrier package or a non-compostable internal layer, which may invalidate the compostable claim. Published data for REVODE290 in this exact capsule configuration is limited; injection moulders often run flow-analysis fill studies with ISO 1133-1:2022 melt mass-flow rate data at 210 °C/2.16 kg to confirm gate and wall selection.

For horticultural clips, plant labels, and root-trainer components, REVODE290 is injection moulded where the intended disposal scenario includes industrial composting or soil contact. The drying requirement remains ≤ 250 ppm moisture. Barrel temperatures are set to 185–210 °C, and mould temperatures of 30–60 °C are usually adequate for amorphous parts, though outdoor heat resistance is limited. For stakes exposed to direct sunlight, high-temperature nucleation or annealing at 70–90 °C for 20–45 min raises crystallinity but shrinks dimensions by 0.5–1.5%; cavity dimensions must compensate. Published tensile strength for similar PLA horticultural parts is 55–65 MPa to ISO 527-2:2012, but impact performance is the weak point: notched Izod is 2.5–3.5 kJ/m² to ISO 180:2019, and thin stakes can crack under mechanical insertion into compacted soil. Ultraviolet exposure degrades unreinforced PLA over one growing season; black or mineral-filled compounds resist UV embrittlement better but may not meet visual labelling requirements. Biodegradation is not rapid in ambient soil; PLA degrades primarily by hydrolysis at elevated temperature and high moisture. Industrial compostability at 58 °C with humidity above 50% is therefore the relevant disposal condition under EN 13432:2000, not home-garden soil burial. No performance claim should be made without specific field ageing data; published data for REVODE290 in these outdoor applications remains limited.