Polylactic Acid REVODE210

In injection moulding of REVODE210 for single-use cutlery, the controlling variable is not barrel set point but actual melt temperature generated by screw speed and back pressure. Because PLA of this flow class undergoes hydrolytic chain scission when pellet moisture exceeds 250 ppm, pre-drying in a desiccant dryer with a dew point of -40 °C or lower, air flow of 1.5–2.0 m³/h per kg/h throughput, and residence time of 4–6 h at 80 °C becomes a hard process boundary rather than a recommendation. On production-scale hydraulic injection machines with screw diameters of 25–40 mm and L/D ratios of 18:1 to 20:1, the melt should be maintained at 190–210 °C at the nozzle; barrel profile settings are typically 170–190 °C in the feed zone, 180–200 °C in the compression zone, and 190–205 °C in the metering zone. Mould temperature is held at 20–35 °C, keeping the injected part below the cold-crystallisation threshold and preserving transparency. Holding pressure is set between 60 MPa and 90 MPa, with holding time of 1.5–3.0 s/mm wall thickness. De-moulding of forks and spoons from multi-cavity tools with 8–32 cavities requires a draft angle of at least 0.5–1.0°, and ejector layout must avoid concentrated stress on thin-tine features. For mechanical performance, specimens conditioned at 23 °C and 50% RH according to ISO 291 typically show tensile yield strength above 60 MPa when tested to ISO 527-2, while notched Charpy impact values remain below 3.0 kJ/m² under ISO 179-1/1eA. The heat deflection temperature under 0.45 MPa load per ISO 75-2 stays below 60 °C, so the cutlery is unsuitable for hot sauces, microwave contact, or continuous hot-liquid service. Production experience shows that if melt residence time exceeds 360 s at 210 °C, or if a hot runner is left without purge for more than 15 min, yellowing and silver streaking appear even when the drying specification has been met. Open hot-runner manifolds should therefore be replaced with valved manifolds, and manifold temperature should not exceed 200 °C. Edge-gate geometry with gate thickness below 0.8 mm causes premature gate freeze and increases residual stress in the tine roots, while thick gates above 1.5 mm extend cycle time without proportional strength gain.

When REVODE210 is extruded into sheet for thermoformed food punnets, edge trim recyclability changes process economics

When REVODE210 is extruded into sheet for thermoformed fruit and vegetable punnets, edge trim recyclability changes process economics because amorphous sheet must be reground and reintroduced at controlled rates to avoid lowering the intrinsic viscosity of the primary melt pool. A single-screw extruder with 30:1 L/D, a barrier screw with a Maddock mixing section, and a melt pump between extruder and flat die is preferred for gauge stability. The barrel profile is ramped from 160–170 °C at the feed throat to 190–200 °C at the die, while the chill roll stack is maintained at 30–50 °C to prevent cold crystallisation and preserve contact clarity. Sheet thickness for punnets ranges from 300 µm to 700 µm, with measured thickness variation controlled to ±5% across the web. Trim scrap is passed through a low-shear granulator with a screen size of 6–8 mm, and regrind is limited to 20–30 wt% because higher addition rates reduce melt strength and produce die-lip drool. Thermoforming on continuous in-line equipment operates with a sheet surface temperature of 75–90 °C, plug assist temperature of 60–80 °C, and forming air pressure of 0.5–0.7 MPa. Punnet sidewalls of 0.25–0.45 mm require matched metal or aluminium tooling with polished surfaces to delay stress whitening. A critical failure mode is localised stress whitening at corner radii; radii below 1.0 mm should be avoided because the oriented amorphous PLA undergoes cavitation before visible cracking. Formed punnets are evaluated for tensile elongation and puncture resistance under ISO 527-3 and ISO 6603-2, respectively. Since the punnet is intended for chilled produce but not for high-moisture hot filling, the practical maximum service temperature under continuous load remains 55 °C; above that, creep deformation and partial shrinkage are observed. If the formed article is labelled compostable, the final punnets must pass disintegration testing per EN 13432 or ASTM D6400, and any barrier coating or printing ink must also be tested under the same scheme.A stable monofilament line drawing REVODE210 for fused filament fabrication feedstock depends on ovality control before water bath quenching, not on nozzle diameter alone. The pellet is pre-dried to below 250 ppm moisture in a compressed-air dryer with a -40 °C dew point and then extruded through a single-screw extruder with L/D of 25:1, a melt pump, and a rod die with dual-axis laser gauge feedback. Barrel temperatures are set lower than injection moulding, typically 175–195 °C, to generate sufficient melt strength for draw-down. The filament passes through a warm water bath at 40–50 °C and a subsequent air cooler before entering a dual-axis laser gauge that controls diameter to 1.75 mm ±0.05 mm. Winding tension at the spooler is held between 0.5 N and 1.5 N; higher tension induces necking and cyclical diameter variation. The process window for this die, quench tank, and spooling configuration is narrow: draw ratio is typically 1.5:1 to 2.5:1, and deviations beyond 2.8:1 trigger draw resonance visible as sinusoidal diameter drift. In FFF printing, the dried filament is processed through a heated nozzle at 200–220 °C onto a bed at 50–60 °C; bed adhesion is improved with a textured PEI sheet or a PLA-compatible adhesive, not with solvent-based primers that may contain ketones and promote stress cracking. Printed tensile bars per ISO 527-2 show layer-direction anisotropy, with Z-axis strength commonly 40–60% of XY-axis strength owing to incomplete interlayer healing and local molecular weight loss at the nozzle. The filament should be stored in a sealed bag with desiccant after opening; moisture uptake above 0.5 wt% is evidenced by popping at the nozzle and brittle printed parts. No antioxidant containing aromatic amines should be compounded into the filament, because amine species accelerate molecular weight loss during extended printing residence time and can discolour the melt.

Can REVODE210 serve as the carrier resin in 40 wt% mineral-filled masterbatch without exceeding 190 °C melt discharge?

Can REVODE210 serve as the carrier resin in 40 wt% mineral-filled masterbatch without exceeding 190 °C melt discharge? The answer depends on filler type and the shear history in the twin-screw extruder. Ground calcium carbonate with a median particle size of 1–3 µm or talc with 2–5 µm median platelet size can be compounded with REVODE210 on a co-rotating twin-screw extruder with 40:1 L/D, side stuffing at barrels 6 to 8, and atmospheric venting at mid-screw. The melt temperature is maintained at 170–190 °C to limit PLA thermal degradation; screw speed is set to 300–500 rpm, and specific mechanical energy input is controlled below 0.35 kWh/kg to avoid disorienting talc platelets and generating fines. With 40 wt% filler, the compound loses translucency and takes on a matte white or off-white appearance, making it suitable for opaque rigid packaging or compostable serviceware. The melt mass-flow rate measured at 210 °C under 2.16 kg per ISO 1133-1:2022 drops substantially relative to unfilled resin, often into the 1–5 g/10 min range, which limits its direct use as a masterbatch carrier in high-flow moulding machines unless diluted with neat REVODE210 at let-down ratios of 10:1 to 20:1. The flexural modulus of the filled compound increases; test specimens conditioned per ISO 291 and loaded in three-point bending per ISO 178:2019 show modulus values above 3,500 MPa, but elongation at break falls to 1–2%, and notched Charpy impact energy per ISO 179-1/1eA falls below 2.0 kJ/m². Incompatibilities include uncoated zinc oxide, stearate-coated fillers that release free stearic acid, and ammonium polyphosphate flame retardants, all of which induce chain scission during compounding. For compostable masterbatch claims, the mineral filler itself must be checked against the ecotoxicity and heavy-metal limits in EN 13432, because filler purity rather than polymer stability is often the limiting factor.

Comparative process thresholds for REVODE210 across four converting lines

Converting line	Pellet moisture limit	Melt or threshold temperature	Maximum addition or residence	Observed failure mode
Injection moulding	<250 ppm	190–210 °C at nozzle	360 s at 210 °C	silver streaking, yellowing
Sheet extrusion / thermoforming	<250 ppm	190–200 °C at die	20–30 wt% regrind	die-lip drool, melt strength loss
Monofilament	<250 ppm	175–195 °C barrel	1.5:1–2.5:1 draw ratio	draw resonance, ovality drift
Twin-screw masterbatch	<250 ppm	170–190 °C melt discharge	40 wt% filler, 0.35 kWh/kg SME	chain scission, filler breakdown

High-speed moulding of transparent PLA beakers with wall sections below 1.0 mm forces a trade-off between filling pressure and gate freeze time. Because REVODE210 has relatively low melt elasticity and strong shear-thinning behaviour, the injection unit must deliver high volumetric flow without exceeding the shear rate threshold at which melt fracture begins at the gate. A hydraulic accumulator on the injection circuit or an all-electric machine with 300–500 mm/s injection velocity is used to fill a 4+4 or 8+8 hot-runner stack mould. The melt temperature at the nozzle is held at 200–210 °C, the hot runner at 195–205 °C, and the mould at 20–30 °C to freeze the transparent amorphous part quickly. Holding pressure is set at 60–80 MPa with switch-over at 95–98% of fill volume; a delay of 0.1 s in switch-over can generate flash along the slightly open parting line. Cooling time for a 0.8 mm sidewall is 4–6 s, and total cycle time on a 180-ton toggle machine commonly falls between 8 s and 12 s. The limiting packaging performance requirement is top-load resistance: beakers tested under ISO 12048 compression exhibit brittle sidewall cracking when wall thickness drops below 0.7 mm, and the open brim should be reinforced with a rolled or double-folded lip. Field failures in high-speed lines occur when regrind levels exceed 20 wt% or when the resin is left in the hopper under high humidity; moisture causes near-instantaneous viscosity loss in the screw and produces parts with visible silver streaks. The drying unit should therefore be interlocked with the feed system to stop the press when return-air dew point rises above -20 °C. If the beaker is printed or sleeved, the ink or label must not restrict disintegration, and the final article should be tested for migration under EU 10/2011 if intended for direct food contact.

Foamed seafood trays via tandem extrusion and supercritical CO₂ injection

Foamed seafood trays via tandem extrusion and supercritical CO₂ injection use REVODE210 as the main polymer phase when density reduction below 0.25 g/cm³ is required for compostable cold-chain packaging. The primary extruder melts and devolatilizes the PLA, while the secondary extruder cools the gas-laden melt to 140–160 °C before the annular or flat die. CO₂ is injected at 7–10 MPa through a positive-displacement pump into the secondary extruder barrel, where distributive mixing elements disperse the supercritical phase; the pressure must be maintained above the critical point of 7.38 MPa and 31 °C to avoid premature phase separation. The die opening is designed to produce a pressure drop of 3–5 MPa, and the extrudate expands immediately at the die exit. A cooling and calibrating mandrel or plate stack then stabilizes the foam skin and prevents post-expansion collapse. Foam density is measured by ISO 845, and compression stiffness by ISO 844. Closed-cell content is determined by a gas pycnometer method according to ASTM D6226; for PLA foam trays, a closed-cell content above 85% is required to limit water absorption in chilled seafood display. The practical processing limitation is that PLA’s low melt strength causes cell coalescence if the die temperature exceeds 160 °C, producing large open voids and visible surface skin defects. A nucleating agent such as talc at 0.5–1.0 wt% is added to increase cell density; without nucleant, cell size distributions become bimodal and the tray sidewall shows non-uniform expansion. The final tray is intended for short shelf-life use at 0–4 °C, not for hot food or freezer storage below -20 °C, because the foam becomes brittle at low temperatures and may crack during handling.

Compliance and test matrix for REVODE210 downstream articles

Property or requirement	Test method or standard	Downstream relevance
Melt mass-flow rate	ISO 1133-1:2022	injection moulding, filament, masterbatch
Tensile properties of rigid plastics	ISO 527-2:2012	cutlery, beakers, serviceware
Tensile properties of films and sheets	ISO 527-3:2018	sheet, thermoformed punnets, blown film
Flexural properties	ISO 178:2019	cutlery, filled compounds
Notched Charpy impact	ISO 179-1:2010	rigid packaging, serviceware
Heat deflection temperature	ISO 75-2:2013	hot-fill and service-temperature limits
Compostability of packaging	EN 13432:2000, ASTM D6400-23, ISO 17088:2021	all compostable claims
Foam density / compression	ISO 845:2009, ISO 844:2014	foamed seafood trays
Dart impact of film	ISO 7765-1:1988	PBAT/PLA flexible film

At melt temperatures below 230 °C, REVODE210 can be melt-blended with poly(butylene adipate-co-terephthalate) to reduce film brittleness, but the screw configuration must address the high viscosity ratio between the two phases. PBAT has a lower melt viscosity and excellent elongation, while PLA contributes stiffness and gloss. A co-rotating twin-screw extruder with 48:1 L/D, a distributive mixing section after the first kneading block, and a vacuum vent at -0.09 MPa is used. The PLA is fed into the main feed, and PBAT is added either in the main feed or through a downstream side feeder to limit residence time. Barrel temperatures range from 160 °C in the first zones to 180–190 °C at the die. The blend is pelletized under water-ring cutting; strand pelletizing is less suitable because the elastic PBAT phase causes strand sagging. Blown film extrusion of the blend on a die with 2.0–2.5 blow-up ratio and a frost line height of 200–400 mm produces film with thickness of 20–50 µm. At 20–30 wt% PBAT, transverse direction tensile elongation can exceed 300% when measured by ISO 527-3, but film clarity is sacrificed; at PBAT levels above 50 wt%, the film becomes tacky on the collapsing frame. Blocking is reduced by adding 1–3 wt% of an erucamide-free antiblocking masterbatch, because high-temperature migration of some slip agents creates organoleptic taint in compostable food packaging. The final blown film is assessed for dart drop impact by ISO 7765-1 and for tear resistance by ISO 6383-2. For compostability, the blend must meet the disintegration and ecotoxicity requirements of EN 13432; formulations with PBAT above 70 wt% may still comply, but the PLA component must remain below the crystallinity threshold that retards biodegradation.