CiaoPlas™ PLA212 NAT is an unfilled, natural-colour polylactic acid (PLA) thermoplastic supplied as cylindrical pellets. The grade is intended for injection moulding, sheet extrusion, and extrusion-grade compound formulation without impact modifiers, mineral fillers, pigments, or nucleating additives. The NAT designation identifies an unpigmented resin, although prolonged heat history may produce slight yellowing. The material is biodegradable only under controlled industrial composting conditions; no soil, marine, or home-compost claim is attached unless separately verified. Melt flow rate measured under 2.16 kg load at 210 °C is 6 g/10 min according to ISO 1133-1:2022. Tensile yield strength measured on dry-as-moulded ISO 527-1A specimens is 60 MPa and tensile modulus is 3.5 GPa according to ISO 527-2. Density is 1.24 g/cm³ according to ISO 1183-1. Heat deflection temperature under 0.45 MPa load is 55 °C according to ISO 75-2/B, and the melt peak by differential scanning calorimetry is 175 °C at 10 °C/min according to ISO 11357-3.

Melt-state hydrolysis is the primary degradation pathway in PLA212 NAT. Pre-drying is required when pellet moisture exceeds 400 ppm; typical desiccant drying conditions are 80 °C for 4 h at a dew point below -40 °C. At ambient relative humidity above 60 %, unprotected pellets can reach equilibrium moisture contents above 2,500 ppm within 24 h. The observed production-scale failure modes on hopper-fed injection machines are screw feeding instability, melt viscosity loss, and increased part brittleness caused by hydrolytic molecular weight reduction.

What Distinguishes CiaoPlas™ PLA212 NAT from Impact-Modified, Nucleated, and Filled PLA Grades?

PLA212 NAT is an unmodified polylactide rather than a multi-phase compound. It does not contain PBAT, PBS, or core-shell impact additives, so elongation at break is 3.5 % per ISO 527-2 and notched Izod impact strength is 2.5 kJ/m² per ISO 180/1A. These values are lower than impact-modified PLA/PBAT blends, which typically exhibit elongation above 150 % and notched Izod above 25 kJ/m², but the unmodified grade retains higher modulus and higher light transmittance. Optical transmittance measured on 2 mm injection-moulded plaques according to ASTM D1003-21 is above 88 % for PLA212 NAT, whereas impact-modified PBAT blends often fall below 50 % at the same thickness because dispersed elastomer domains scatter light. When compared with nucleated high-HDT PLAs, PLA212 NAT has a lower heat deflection temperature, approximately 55 °C at 0.45 MPa, compared with 85 °C to 100 °C for annealed or nucleated grades, but it does not require the elevated mould temperatures or post-mould annealing that high-crystallinity PLAs demand. Filled PLAs containing talc, calcium carbonate, or glass fibre show higher modulus and lower shrinkage, but they also increase screw and barrel wear, reduce clarity, and alter melt rheology; PLA212 NAT avoids these filler-related process interactions.

The comparative values are representative ranges drawn from commercial polylactide datasheets; exact values for a given supplier may shift according to molecular weight, D-lactide content, and additive package.

Thermal and Rheological Boundaries for Twin-Screw Compounding and Sheet Extrusion

On a co-rotating twin-screw extruder with an L/D ratio of 32:1 and atmospheric venting, a melt temperature window of 185 °C to 210 °C is preferred for PLA212 NAT. Barrel settings from feed throat to die commonly follow a profile of 180 °C, 190 °C, 200 °C, 205 °C, 200 °C, and 195 °C. Screw speed is typically 200–350 min⁻¹; at 250 min⁻¹ the specific mechanical energy input measured on production-scale machines is 0.25–0.35 kWh/kg. Melt temperature excursions above 230 °C accelerate random chain scission and produce lactide and acetaldehyde volatiles; the processing window is therefore narrow, with die melt temperature controlled to ±5 °C. If the line is stopped for more than 15 min, the screw should be purged with virgin PLA212 NAT or the melt should be kept moving because stagnant melt in the die and check ring degrades rapidly.

Vented two-stage screws with an L/D ratio of 36:1 are used when PLA212 NAT is compounded with recycled flake or masterbatch. The first stage should include kneading blocks for dispersion, but intense shear should be limited because acid-end generation increases with specific energy. Low-shear screw elements are recommended downstream of the vent. Amine-based stabilizers and unreacted epoxidized chain extenders can interact with lactide or acid end groups and should be introduced only when screw torque and residual molecular weight are monitored. In sheet extrusion, cooling roll temperatures of 25–40 °C promote a predominantly amorphous sheet with good clarity. Higher roll temperatures above 60 °C may induce spherulitic crystallisation and an increase in haze, particularly in sheet thicknesses above 0.8 mm. The recrystallisation temperature of PLA212 NAT is typically 100–120 °C during cooling at 10 °C/min, and this temperature region should be controlled when thermoforming because residual stress from fast cooling can produce post-forming distortion. Published data for this specific grade under high-speed film casting is limited, but the amorphous orientation behaviour is consistent with low-D-lactide PLA.

When Ambient Relative Humidity Exceeds 60% and Regrind Fractions Exceed 30 wt%

Moisture control becomes a process boundary at relative humidity above 60 %. Pellets left in open hoppers or gaylords at these conditions can absorb moisture beyond 2,500 ppm within 24 h, and a moisture analyser with 1 ppm sensitivity should be used to confirm drying before processing. A residual moisture level below 250 ppm is recommended for injection moulding, and below 400 ppm for sheet extrusion. Drying at 80 °C for 4 h in a desiccant dryer is standard, but the temperature should not exceed 90 °C because pellet bridging can occur in the drying hopper. Desiccant wheel dryers should maintain a dew point below -40 °C and air flow in the range 3.5–4.5 m³/h per kg/h throughput. The use of regrind above 30 wt% reduces melt viscosity and part impact strength because repeated thermal history increases acid-end-group formation. Regrind should be blended with virgin material at a consistent ratio and reprocessed within 24 h after drying.

Gate Design and Pressure-Loss Are Dictated by the Lower Viscosity Plateau of Unfilled PLAs

For injection moulding of PLA212 NAT, melt temperature at the nozzle is typically 200 °C to 210 °C, and mould temperature is 25 °C to 35 °C for amorphous parts. Injection pressure measured on production machines is 80–140 MPa, with holding pressure at 60–80 % of peak pressure. Gate diameter for edge gates should be at least 50 % of the nominal wall thickness to avoid freeze-off before packing; submarine gates should be sized at 0.8–1.2 mm for wall stocks up to 2.5 mm. Shear heating in the nozzle can raise melt temperature by 3–7 °C at injection speeds above 100 mm/s; therefore nozzle temperature should be set 5 °C below the barrel front zone. Shrinkage compensation for unfilled PLA212 NAT is typically 0.3–0.5 % in the flow direction and 0.2–0.4 % transverse to flow using ASTM D955-08 measurements on 3.2 mm plaques. These values are lower than those of acetals and nylons but higher than glass-filled PLAs; tool design should locate gates at the thickest section because the low initial melt viscosity promotes rapid jetting in cold runners.

Thermoformed sheet made from PLA212 NAT should be conditioned at 45–55 °C before forming. Below 45 °C the sheet can crack during plug-assisted forming, while above 60 °C the sheet may stick to tooling. Female mould temperature should be maintained at 25–40 °C to preserve clarity; higher temperatures induce crystallinity and increase haze in the finished article. These temperatures are specific to PLA212 NAT and may differ for impact-modified or nucleated PLAs because those materials have a different temperature-dependent modulus.

Under product stewardship documentation, PLA212 NAT may be evaluated for industrial composting according to EN 13432:2000 or ASTM D6400-23. These schemes require disintegration, inherent biodegradability, compost quality, and ecotoxicity testing. Certification is not automatic at the resin level; finished article thickness, print, and additives influence conformity. The resin itself is not a home-compost material, and no marine or soil biodegradability claim is attached unless separately verified under specific test methods.

US FDA status for PLA212 NAT should be confirmed through the supplier’s Food Contact Notification or migration testing because polylactide is not generically covered by a single polymer clearance in the same manner as some conventional polyolefins. Published data for this specific configuration under FDA food-contact conditions is limited, and end-use suitability must be established at the finished-article level.