BBCA Polylactic Acid (PLA) FY802 is processed on reciprocating-screw injection molding machines with a screw 20:1 to 24:1 L/D and a compression ratio of 2.0:1 to 2.5:1. The resin enters the process only after desiccant drying at 80 °C for 4 h with supply air at a dew point of −40 °C; residual moisture above 250 ppm is the primary source of hydrolytic molecular weight loss, splay, and melt-flow instability. Barrel temperature is profiled from 160 °C at the feed throat to 195–205 °C at the nozzle, and any hot runner manifold is held within ±5 °C of the nozzle set point. Melt flow rate is checked at 210 °C under a 2.16 kg load according to ISO 1133-1:2022 as a process-control indicator. Cavity filling is run at injection velocities that deliver 90–95 % volumetric fill within 0.5–1.2 s; holding pressure is set at 55–75 MPa for 2–4 s, with screw-position switchover rather than time-based switchover to reduce shot-to-shot variation. Mold temperature is maintained at 15–30 °C by closed-loop water circulation; mold temperatures above 45 °C without a nucleating agent or post-mold annealing at 90–110 °C induce post-demolding crystallization, stress relaxation, and dimensional instability. End products such as disposable spoons, forks, tasting cups, and delicatessen container lids are evaluated according to ISO 527-2 for tensile yield stress, ISO 178 for flexural modulus, ISO 179-1/1eA for notched Charpy impact strength, and ISO 75-2/B for heat deflection temperature. Food-contact suitability is assessed by overall migration testing under EN 1186-1 against the 10 mg/dm² limit in EU Regulation (EC) No 10/2011. Production-scale observations from multi-cavity foodservice molds show that sharp step changes in nozzle tips generate hydrolysis streaks; free-flow nozzles with a 2.5–4.0 mm bore and polished carbide inserts reduce black specks. Zinc stearate release agents are avoided because zinc salts migrate to the part surface and form white haze around ribs and boss features.

What Limits Thermoforming Depth in Cold-Chain PLA Trays?

Sheet extrusion for cold-chain food trays and pharmaceutical transport trays is carried out on a single-screw extruder with a 30:1 L/D barrier screw and a coat-hanger die having a lip gap of 0.6–1.2 mm. Melt temperature at the die lip is held between 180 °C and 205 °C; a nitrogen purge is applied to the roll stack when ambient relative humidity exceeds 60 %. The cast sheet is cooled on a three-roll polishing stack with roll temperatures of 35–50 °C for the top roll, 30–40 °C for the middle roll, and 20–30 °C for the bottom roll. Deep-draw forming above a 1:1 draw ratio requires plug-assisted thermoforming with syntactic foam plugs heated to 70–90 °C. The forming window is narrow because sheet surface temperatures below 75 °C produce corner fractures, while surface temperatures above 110 °C cause uncontrolled sag and severe wall thinning. Published data for this specific configuration with PLA FY802 is limited; however, production lines processing PLA sheet report that moisture above 300 ppm before extrusion reduces molecular weight and lowers puncture impact. Formed parts are tested according to ISO 6603-2 at 4 °C and 23 °C, and ISO 527-3 for tensile strength and elongation in both machine and transverse directions. For cold-chain applications, post-forming annealing at 80–90 °C for 20–30 min raises the Vicat softening temperature measured under ISO 306/B50 from 55–58 °C to 64–72 °C. End products include seafood trays, berry clamshells, and insulated box liners where the maximum service temperature does not exceed the annealed Vicat limit.

For extrusion coating of paperboard and moulded fibre for cold-beverage cups, dairy dessert cups, and fresh-produce punnets, PLA FY802 is processed at a melt temperature of 200–215 °C and a screw speed of 80–120 rpm on single-screw extruders with screw diameters of 45–90 mm and an L/D of 24:1 to 30:1. The polymer is delivered to a flat die with an internal deckle adjusted for a coating weight of 15–25 g/m². Paperboard is corona-treated to 38–42 mN/m surface tension immediately before the nip, and the chill roll is held at 12–18 °C. Coating adhesion is measured by peel testing under ISO 11339. Melt curtain stability is the critical process parameter: below 195 °C, edge neck-in widens and produces uncoated board edges, while above 220 °C lactic acid volatiles condense on the die lip and generate coating streaks. Screw configuration is specified without high-shear mixing torpedoes; a barrier flight design reduces residence time by 15–20 % compared with a general-purpose screw, which reduces molecular weight loss. Coated board is tested by the Cobb method under ISO 535 for water absorption and by gravimetric coating weight determination on 100 mm × 100 mm specimens. Compliance for aqueous and acid food contact is evaluated under EU Regulation (EC) No 10/2011 and, for markets requiring United States clearance, under the applicable FDA food contact notification for polylactic acid; no single 21 CFR citation covers all PLA coating structures.

When Impact Modifiers Are Compounded into PLA FY802 for Closure Systems

Compounding PLA FY802 with ethylene-butyl acrylate-glycidyl methacrylate terpolymer at 4–12 wt% and an epoxy-functional styrene-acrylic chain extender at 0.2–0.5 wt% is performed in a co-rotating twin-screw extruder with an L/D of 40:1 and screw diameters of 25–40 mm. The impact modifier is introduced through a side feeder after the PLA melting zone; adding it at the main throat reduces shear transfer into the PLA and creates unmelted gel particles that survive a 120-mesh screen pack. Barrel temperatures are set from 170 °C in zone 1 to 190 °C in zones 4–8. Vacuum devolatilization at −0.08 MPa to −0.095 MPa follows the mixing zone to remove residual lactide and moisture. Screw speed is maintained at 300–600 rpm, and specific mechanical energy is kept between 0.18 kWh/kg and 0.24 kWh/kg to limit chain scission. The toughened compound is subsequently injection molded into flip-top closures, fragrance caps, and jar lids. Notched Charpy impact strength measured under ISO 179-1/1eA typically improves from 2–4 kJ/m² for unmodified PLA injection grades to 8–15 kJ/m² at 10 wt% modifier, although published data for this specific grade and modifier combination is limited. Tensile modulus, measured under ISO 527-2/1A, decreases to 1800–2200 MPa at 10 wt% modifier, which affects the stiffness of tamper-evidence ribs. Heat deflection temperature under ISO 75-2/B remains below 55 °C for unannealed mouldings; closures intended for warm-fill environments above 50 °C are unsuitable without post-mold annealing at 70–80 °C for 15–30 min. Amine-containing melt stabilizers are avoided because amine species accelerate PLA transesterification at processing temperatures above 200 °C and reduce molecular weight.

Fused Filament Fabrication Feedstock: Dimensional Tolerance, Melt Strength, and Spool Moisture Control

Monofilament extrusion for fused filament fabrication feedstock from PLA FY802 uses a single-screw extruder with an L/D of 24:1, a screw diameter of 25–30 mm, and a melt pump downstream of a 60/100 mesh screen changer. Melt temperature at the die is controlled between 190 °C and 205 °C, and the die hole diameter is 2.0–3.0 mm. The filament is quenched in water at 18–25 °C and drawn at a draw ratio of 1.8:1 to 2.2:1 to a final diameter of 1.75 mm ± 0.05 mm or 2.85 mm ± 0.05 mm. Dual-axis laser gauging at 1 Hz intervals maintains ovality within ±0.03 mm; higher ovality causes intermittent feeding and hot-end jamming. Melt strength limits stable drawing: when melt temperature exceeds 210 °C, the filament sags between the die and the water bath and roundness is lost. Winding tension is kept at 0.5–1.5 N. Spools are sealed with desiccant and moisture barrier film immediately after winding; PLA filament exposed to 50 % RH at 23 °C can absorb surface moisture within 8–12 h, and moisture above 400 ppm generates steam pops and surface blistering at the print nozzle. Printed parts are characterized under ISO 527-2 for tensile strength and ISO 178 for flexural strength after standardized print orientations. End products include jigs, fixtures, inspection gauges, and sacrificial tooling patterns for room-temperature casting where acetone resistance is not required.