Transparent thin-wall packaging grades of PLI 012 are converted on reciprocating-screw injection-moulding machines after the material is dried to a residual moisture content at or below 250 ppm (0.025% by weight). Drying is carried out in a desiccant dryer with an air temperature of 75 °C to 80 °C, a dew point no higher than −40 °C and a residence time of 4 h; this is not a nominal recommendation but a release criterion, because hydrolytic degradation of PLA during melting is rapid once free water is present. The effect is first observed at the screw tip as melt-pressure trace instability and nozzle drool, then as splay and silver streaks on the part surface; the viscosity loss is measurable by comparing melt-flow rate before and after drying according to ISO 1133-1:2022. A typical thin-wall tool is filled from a barrel zoned at 170 °C at the feed throat to 200 °C in the metering section, with nozzle temperature held between 195 °C and 210 °C; the mould is circulated at 15 °C to 30 °C so that the polymer freezes in its amorphous, transparent state rather than crystallising into a translucent white structure. Screw geometry is general purpose with an L/D of 20:1 to 24:1 and compression ratio 2.5:1 to 3.0:1; in the processing window PLA is shear-thinning, and a power-law index near 0.6 is used for preliminary screw design, though grade-specific capillary rheometry per ISO 11443 should replace it. Injection velocity is set at the highest rate that does not cause jetting at the gate; first-stage injection pressure typically falls in the 80 MPa to 120 MPa range, and hold pressure is maintained until the gate seal is confirmed by part-weight stabilisation. Barrel residence time is kept below 5 min, and any zone above 230 °C is treated as a thermal-overload condition because PLA can undergo chain scission, lactide reformation and brown discoloration. Transparent disposable articles—portion cups, deli lids, salad bowls and clamshell inserts—are evaluated for haze according to ASTM D1003, tensile yield strength according to ISO 527-2, notched impact resistance according to ISO 179-1 or ASTM D256, and heat deflection temperature under ISO 75-2 at 0.45 MPa. The compostability claim for the finished article is validated under EN 13432:2000 or ASTM D6400-21 through disintegration, biodegradation, ecotoxicity and heavy-metal thresholds, while food-contact migration is assessed under Regulation (EU) No 10/2011 using simulant protocols from the DIN EN 1186 series. Published data for this specific PLI 012 formulation are limited for some optical and mechanical values, so each lot is benchmarked after drying and moulding rather than relying on generic PLA datasheet values.

Why Does Thermoforming PLI 012 Demand a Sheet-Surface Temperature Below the Cold-Crystallisation Onset?

Thermoforming of transparent PLI 012 cups and trays is governed by the temperature interval between the glass transition and the cold-crystallisation exotherm. Differential scanning calorimetry under ISO 11357-2 in a 10 K/min scan generally locates the PLA glass transition at 55 °C to 60 °C and the cold-crystallisation onset between 95 °C and 110 °C; once the sheet surface enters the crystallisation regime, spherulitic growth creates haze that can exceed 5% at 1.0 mm section when measured by ASTM D1003. For this reason, the forming station is operated with an IR pyrometer-controlled surface temperature of 85 °C to 95 °C, not the higher sheet settings used for amorphous PET. The heater bank is zoned so that the clamp frame and trim edges remain below the forming temperature and hold the sheet under tension; ceramic or quartz emitters are selected for their wavelength response in the 3 μm to 5 μm range, which PLA absorbs more evenly than near-infrared radiation. Plug-assisted vacuum forming uses a plug temperature of 60 °C to 80 °C and a vacuum of −0.06 MPa to −0.09 MPa; if the plug is too cold, contact chilling drops the sheet below the glass transition and the part fails by webbing or fracture at the plug mark. Ejection is delayed until the formed part is below 50 °C to avoid stress whitening and distortion above the heat-deflection range. Sheet for this route is produced at melt temperatures of 180 °C to 210 °C and is polished through a three-roll calender with roll temperatures stepped from 50 °C to 30 °C to preserve the amorphous state. Regrind is limited to 20 wt% because repeated heat cycles lower the cold-crystallisation onset and narrow the remaining forming window. The final parts are assessed for dimensional stability after filling with cold or ambient liquids, not hot-fill, because typical PLA heat deflection temperature at 0.45 MPa is only 50 °C to 55 °C; any hot-fill claim would require a crystallised PLA grade or heat-setting step. Compostability validation follows EN 13432:2000 for industrial composting, and food-contact migration testing follows DIN EN 1186 under Regulation (EU) No 10/2011. Published data for the precise crystallisation kinetics of this grade are limited, so processors should run a differential scanning calorimetry scan on each lot before setting heater profiles.

When PLI 012 is extruded as a monolayer cast film for dry-food lidding and small sachet overwrap, the critical controls are melt curtain stability, quench-roll temperature and heat-seal initiation. The resin is dried to below 250 ppm moisture as for injection moulding, and the extruder is kept in the 180 °C to 210 °C melt-temperature band; die lip gaps are set between 0.4 mm and 0.6 mm for film thicknesses from 20 μm to 50 μm. The quench roll is held at 15 °C to 40 °C so that the film remains amorphous and transparent; if the roll is too cold, condensation can create surface defects, and if it is too warm, the web can stick and wrap. Film produced in this range is tested for heat-seal strength on a laboratory sealer at seal-bar temperatures between 95 °C and 120 °C, and the peel force is measured by ASTM F88/F88M at a separation speed of 200 mm/min to 300 mm/min. Because amorphous PLA seals by interfacial softening rather than brisk melting, the dwell time and jaw pressure are larger than those used for LDPE; the seal-initiation temperature must be established for each thickness because thinner film can overheat and pucker. Moisture-vapour barrier is a known limitation: PLA has a moderate water-vapour transmission rate that is higher than PET, and converters measure it by ISO 15106-3 or ASTM F1249 rather than assuming barrier equivalence. The lidding application is therefore restricted to dry or low-moisture foods, and the package is not designed for retort, high-humidity long shelf life or microwave exposure unless a separate barrier layer is added. Compostability of the final laminate, where applicable, is assessed under EN 13432:2000; printed and coated structures may require separate evaluation because inks and adhesives can exceed the allowable heavy-metal and ecotoxicity limits.

Extrusion Sheet Lines and the Management of Feed-Zone Bridging

On a monolayer sheet line converting PLI 012 into semi-finished rollstock for thermoforming, the process begins in the feed zone rather than at the die. PLA pellets can bridge in the hopper if the feed-throat temperature rises above 45 °C; the throat is therefore cooled with water at 20 °C to 35 °C and the hopper is fitted with an anti-bridging device. A single-screw extruder with 30:1 L/D and a barrier screw or low-shear mixing section is preferred; compression ratio is typically 2.5:1 to 3.0:1, and barrel temperatures are set from 170 °C at the rear zone to 200 °C at the front zone, with the adapter and flat die at 200 °C to 210 °C. Melt pressure before the die is held steady, often with a gear pump, because pressure pulsation translates directly into thickness variation in 0.3 mm to 1.0 mm sheet. The three-roll calender stack is run with roll temperatures of 50 °C, 40 °C, and 30 °C from top to bottom; the polished rolls preserve surface gloss, while excessive roll pressure creates internal orientation that can later release as warp during thermoforming. Edge trim is reground through a low-dust granulator and dried with the virgin resin; the regrind fraction is limited to 20 wt% unless a crystallised fraction is separately removed by density or colour sorting. The use of strongly alkaline fillers or amine-based processing aids is avoided because they accelerate hydrolytic chain scission during subsequent extrusion; compatibility is checked by melt-flow-rate drift after a drying cycle. Static pinning wires and antistatic bars are set to control web wander and dust attraction, but lubricants or release agents must be food-contact approved if the sheet is destined for food packaging. Thickness profile is measured continuously with a beta or X-ray gauge, and optical quality is checked by ASTM D1003 haze measurements on sheet specimens conditioned per ISO 291. Processing data for this specific grade are limited in the open literature; the operating window described here is established from general PLA sheet-extrusion practice and must be confirmed on the installed line.

Filament extrusion from PLI 012 for fused filament fabrication is judged primarily by diameter stability, ovality, and moisture level at the spool. The resin is dried to below 250 ppm water and extruded on a single-screw or twin-screw compounding line at 180 °C to 200 °C, passed through a melt filter to remove gels, and drawn through a water bath at 20 °C to 30 °C. Filament diameter is controlled with a laser micrometer in closed-loop mode; the common tolerances are 1.75 mm ± 0.05 mm and 2.85 mm ± 0.05 mm, while higher-end users require ± 0.03 mm. Ovality is held below 5% of the nominal diameter, and the spooled filament is conditioned in a sealed container with desiccant because PLA reabsorbs atmospheric moisture at relative humidity above 60%. Printing feedstock made from this resin is not a substitute for annealed, impact-modified PLA when the printed part must carry sustained load above 50 °C; the heat deflection temperature under 0.45 MPa remains in the 50 °C to 55 °C range unless annealing is applied, and annealing introduces dimensional shrinkage that must be compensated in the toolpath. The compostability of printed articles follows EN 13432:2000 only if all pigments and additives in the filament are themselves compliant; colour masterbatch loadings can alter the discontinuous qualification result. Published data for this specific resin in filament form are limited, so the diameter control window is set by line capability rather than by an assumed rheological curve.

When PLI 012 Is Used in Extrusion Blow Moulding, Parison Melt Strength Sets the Bottle Wall

Extrusion blow moulding of transparent PLI 012 containers is technically possible only when the parison does not elongate uncontrollably under its own weight. General-purpose PLA has lower melt strength than high-density polyethylene or PET, so the die temperature is kept near 185 °C to 200 °C, the parison drop time is shortened, and the mould closes quickly. The mould is chilled to 10 °C to 20 °C to freeze the amorphous wall and prevent haze from slow crystallisation. Wall thickness is controlled by die profiling and parison programming; thin spots lead to stress cracking at the pinch-off weld, while parison sag produces an uneven wall and excessive scrap. Bottle articles made from PLA are limited to cold-fill applications below 40 °C; they are not submitted for carbonated-beverage pressure retention unless a multilayer structure or chain-extended PLA is used. This is a meaningful limitation: the same resin that produces a clear injection-moulded cup may not produce a commercially stable bottle on a wheel-type blow moulder without melt-strength modification. Testing of the finished bottle includes drop impact at 5 °C, stack compression, and closure torque retention; if food contact is claimed, the bottle is tested under DIN EN 1186 migration protocols and Regulation (EU) No 10/2011. Compostability is verified under EN 13432:2000, but the label and closure must be included in the packaging unit assessment. Published data for PLI 012 in extrusion blow moulding are sparse, so processing trials are required before quoting cycle time or wall distribution.