Ceramis-PLA High Barrier Transparent Compostable Polylactic Acid is a compounded polylactic acid formulation supplied as cylindrical pellets for blown film, cast film, sheet extrusion, thermoforming, and injection stretch blow molding. The commercial grade designation is Ceramis-PLA-HB-T for thick sheet and Ceramis-PLA-HB-F for thin film; both grades share the same base resin and differ only in melt volume-flow rate. The material is specified with a melt volume-flow rate of 3.0 cm³/10 min to 6.0 cm³/10 min at 190°C under 2.16 kg load in accordance with ISO 1133-1:2022, and a density of 1.24 g/cm³ to 1.26 g/cm³ determined by ISO 1183-1:2019. The compound is transparent in sheet and film form, with light transmittance above 90% and haze below 5% on a 1.0 mm injection-molded plaque when tested according to ASTM D1003-21. The high-barrier function is achieved without polyvinylidene chloride or ethylene vinyl alcohol copolymer, allowing the finished article to remain compatible with industrial composting criteria under EN 13432:2000 and ASTM D6400-23 when the total package wall thickness does not exceed the standard’s maximum disintegrating fraction limit. Because the exact modifier chemistry is proprietary, published data for this specific configuration is limited; supplier documentation indicates only that the formulation contains no halogenated compounds, no aromatic isocyanates, and no intentionally added per- and polyfluoroalkyl substances.

Barrier performance and industrial compostability are concurrent design constraints.

Unmodified PLA has a relatively low oxygen transmission rate compared to polyolefins, but its water vapour transmission rate remains high enough to limit shelf life in dry-food packaging. In Ceramis-PLA-HB-T, the supplier technical data sheet reports oxygen transmission rate below 50 cm³/(m²·day·bar) for 25 µm biaxially oriented film at 23°C/0% RH according to ASTM D3985-17, and water vapour transmission rate below 20 g/(m²·day) for 25 µm biaxially oriented film at 38°C/90% RH according to ISO 15106-3:2005. Independent verification of these values in published peer-reviewed studies is limited; converters should qualify the film on the target packaging line with a 10 cm² diffusion cell or equivalent permeation instrument. The industrial compostability certification covers the unfilled compound only; printed or adhesive-laminated structures must be re-evaluated under EN 13432:2000 Clause 5 because coatings and inks can alter disintegration behaviour in a controlled composting test.

In blown-film conversion, Ceramis-PLA-HB-F is dried in a desiccant drier to a residual moisture content below 250 ppm before extrusion. The melt temperature at the die is maintained between 185°C and 200°C, and the die gap is set to 0.8 mm to 1.2 mm to limit shear heating. Screw configurations with L/D ratios from 24:1 to 30:1 and low-shear mixing sections are preferred because prolonged residence times above 210°C accelerate molecular weight loss and increase film haze due to lactide reformation. The frost line height is held at 2 to 3 die diameters to balance bubble stability and optical clarity; the blow-up ratio is typically 2.0:1 to 3.0:1. In cast film, the chill roll temperature is set at 15°C to 25°C to reduce crystallisation-induced haze. Published data for this specific configuration is limited because the exact high-barrier modifier can alter melt elasticity and bubble stability compared to unmodified PLA.

For sheet extrusion, the melt temperature is set at 180°C to 210°C, and the polishing roll temperatures are 30°C to 60°C. Thermoforming of Ceramis-PLA-HB-T requires sheet surface temperature between 90°C and 110°C; below 90°C the sheet may craze during drawing, and above 110°C the sheet can sag and produce non-uniform wall thickness. Plug-assisted forming with a plug temperature of 80°C to 100°C is recommended for draw ratios above 1.5:1.

What Process Deviations Cause Loss of Optical Clarity in High-Barrier PLA?

Loss of clarity in Ceramis-PLA occurs primarily when the melt temperature at the die exceeds 210°C or when the melt residence time exceeds 8 min. Under these conditions, depolymerization of the PLA backbone generates lactide and oligomers that migrate to the film surface and scatter visible light. The resulting haze increase is measurable by ASTM D1003-21, typically rising from below 5% to above 12% on a 1.0 mm plaque. In production-scale cast film trials on a 75 mm single-screw extruder with a 30:1 L/D ratio, die-lip buildup appears after 6–8 h when barrel zone temperatures exceed 205°C; this failure mode is mitigated by reducing the feed zone temperature to 170°C and using a screen pack with 120 mesh maximum aperture to filter oligomeric residues.

Obtained on a parallel-plate rotational rheometer at 190°C, the zero-shear viscosity of the dried compound is between 1800 Pa·s and 2500 Pa·s. At a shear rate of 100 s⁻¹, the viscosity falls to 250 Pa·s to 350 Pa·s; at 1000 s⁻¹, it is approximately 80 Pa·s. The power-law index over 10 s⁻¹ to 1000 s⁻¹ is 0.60 to 0.70. These values should be used for extruder torque and head pressure calculations; extruder barrel zones above 205°C can produce a reduction in zero-shear viscosity of more than 20% within 5 min residence time.

The second major source of haze is moisture. If the residual moisture exceeds 250 ppm at the feed throat, hydrolysis during extrusion reduces molecular weight and produces free lactic acid that can condense on the die lips. The processing window at high ambient humidity is therefore narrow; in plants where relative humidity exceeds 60%, the pellets must be maintained in closed desiccant hoppers and the feed throat purged with dried air at a dew point of −40°C or lower. Avoid compounding with amine-based chain extenders in this grade because residual amines can accelerate transesterification and increase oligomer formation.

When High-Barrier PLA Replaces Fossil-Based PET in Rigid Packaging

When Ceramis-PLA-HB-T is used as a replacement for fossil-based polyethylene terephthalate in injection stretch blow molding, the preform design must be adjusted for the lower intrinsic viscosity and higher melt density of the PLA melt. Injection-molded preforms are dried to ≤ 250 ppm residual moisture and processed at a barrel temperature of 175°C to 190°C with a mold temperature of 10°C to 15°C. For multi-cavity preform injection, a clamp force of 4–6 kN/cm² of projected area is sufficient; higher clamp forces may induce over-packing and increase gate blush. The lower glass transition temperature of PLA, near 58°C as measured by ASTM D3418-21, limits the filling temperature for hot-fill applications to below 50°C unless a heat-set blow mold at 120°C to 130°C is used. Published data for this specific configuration is limited because the exact heat-set cycle depends on preform wall thickness and blow mold surface finish.

In rigid packaging, the high-barrier grade reduces oxygen ingress compared to unmodified PLA enough to protect oxygen-sensitive dry foods for a shelf life of 6–12 months in a sealed package at 23°C/50% RH according to accelerated shelf-life models; however, the water vapour transmission rate remains higher than that of a 25 µm oriented PET film under the same conditions. Therefore, the grade is not recommended for long-term packaging of desiccant-sensitive powders unless a secondary moisture barrier is used. Compared to PVDC-coated PLA, Ceramis-PLA-HB-T avoids halogenated barrier coatings and remains compatible with industrial composting under EN 13432:2000, whereas PVDC-coated films may fail the disintegration and ecotoxicity requirements because of the coating residue.

Comparative Performance Against Unmodified PLA and PBAT Blends

A comparison with an unmodified PLA grade of equivalent melt volume-flow rate shows that Ceramis-PLA reduces oxygen transmission rate by approximately one order of magnitude on a 25 µm biaxially oriented film under 23°C/0% RH conditions. Unmodified PLA typically shows an oxygen transmission rate in the range of 400 cm³/(m²·day·bar) to 600 cm³/(m²·day·bar) under the same conditions, whereas the high-barrier grade is specified below 50 cm³/(m²·day·bar). Water vapour transmission rate is likewise reduced, although the exact ratio depends on film orientation, crystallinity, and storage humidity. Unlike polybutylene adipate terephthalate blends, Ceramis-PLA retains a tensile modulus above 3000 MPa and light transmittance above 90%; PBAT addition at 30 wt% typically lowers modulus below 1200 MPa and increases haze above 20% as measured on 1.0 mm plaques under ASTM D1003-21. The difference in modulus affects package stiffness and web handling: a 25 µm Ceramis-PLA film can be converted on vertical form-fill-seal machines designed for 20–30 µm PET films, whereas PBAT-rich films usually require downgauging or additional support layers.

The high-barrier modifier also affects the crystallization rate. Non-isothermal cooling at 10°C/min according to ISO 11357-3:2018 shows a crystallization peak onset around 95°C, whereas unmodified PLA of similar viscosity shows onset around 105°C. This difference requires lower chill roll temperatures in cast film and lower polishing roll temperatures in sheet extrusion to limit quiescent crystallinity and maintain haze below 5%. Published data for this specific configuration is limited, and converters should determine the cooling curve on the actual line because the addition level of the barrier modifier is not disclosed. Against ethylene vinyl alcohol copolymer multilayer structures, the single-layer Ceramis-PLA film eliminates the need for tie layers and reduces the number of extruder layers from 3 to 1 in dry-food laminations; however, published data for this specific configuration is limited for high-moisture retort conditions, and EVOH-based structures remain the reference for oxygen-sensitive retort pouches. Unlike metallized PLA, the transparent high-barrier grade is microwave-transparent and does not require a lacquer overprint for dry packaging.

Verifying Industrial Compostability and Food Contact Compliance

Compostability claims for Ceramis-PLA-HB-T are verified according to EN 13432:2000 Clause 5 for biodegradation, Clause 6 for disintegration, Clause 7 for ecotoxicity, and Clause 8 for heavy metals. The equivalent U.S. designation is ASTM D6400-23; the international designation is ISO 17088:2021. The grade is not certified for home composting with the same disintegration time; industrial composting at 58°C is required. Food contact compliance for the unfilled resin is stated under EU 10/2011 and FDA 21 CFR 175.300 for food-contact coatings and films, subject to end-use testing for migration of the proprietary barrier modifier. The compound is screened for SVHC under REACH 1907/2006 and for restricted substances under RoHS 2011/65/EU Annex II.

Batch-to-batch variation in melt volume-flow rate is specified within ±0.5 cm³/10 min, and moisture content at delivery is below 500 ppm as measured by ISO 15512:2019 Karl Fischer titration. The supplier’s certificate of analysis includes melt volume-flow rate, density, moisture, and haze on a standardized plaque. Converters should request the lot-specific certificate before release for food-contact production because the proprietary barrier modifier can affect overall migration under EU 10/2011.

Storage of unopened pellets is specified at ≤ 40°C and ≤ 60% RH; opened packaging exposed to uncontrolled humidity should be consumed within 8 h or re-dried. The grade is not suitable for retort sterilization above 100°C, for direct contact with highly alkaline foods at pH above 9, or for long-term outdoor exposure without ultraviolet stabilization. Published data for this specific configuration is limited for multi-layer retort structures containing Ceramis-PLA, and end-use validation under the target filling and distribution conditions is required before commercial adoption.