VeryGreen™ VG7232U is an unfilled polylactic acid resin supplied as cylindrical pellets for extrusion, injection molding, and thermoforming of rigid food-service articles. The grade is intended for disposable cutlery, cold-service cups, clamshell containers, and lids in which end-of-life management is industrial composting rather than home compost or soil disposal. Incoming resin lots are controlled to a density of 1.24 g/cm³ per ISO 1183-1:2019 and a melt flow index of 3–8 g/10 min at 210 °C under 2.16 kg per ISO 1133-1:2022 after drying to <250 ppm moisture. Differential scanning calorimetry per ISO 11357-2:2020 places the amorphous-phase glass transition at 55–60 °C and the crystalline melting endotherm between 145 °C and 175 °C, depending on stereochemical composition and thermal history. These values define a rigid-service window: the product is not a flexible-film PLA, not a PBAT-modified tough grade, and not a nucleated high-heat grade.

Because VG7232U is an unmodified PLA, industrial compostability certification is tied to wall thickness and surface area. Thin-walled sections below 1.0 mm are more likely to meet the 12-week disintegration window than thick sections above 3.0 mm, because disintegration proceeds from the surface and depends on surface-to-volume ratio. Converters should avoid unnecessary thickness in areas where compliance with EN 13432:2000 or ASTM D6400-19 is required.

What Processing Boundaries Must Be Observed During Melt Conversion?

Moisture control is the primary constraint. PLA undergoes hydrolytic chain scission at melt temperatures; residual moisture above 250 ppm produces a measurable increase in melt flow index and loss of melt strength within 10–15 min at 200 °C. Pellets must be conveyed to a desiccant dryer with supply air dew point not exceeding −40 °C. Drying at 80 °C for 4 h is the minimum condition from sealed, undamaged packaging. Drying at 60 °C is insufficient when regrind exceeds 20 wt%. Extended drying above 12 h at 80 °C can cause surface hydrolysis and yellowing in poorly sealed hoppers.

Single-screw extrusion should use a 24:1 to 30:1 L/D screw with compression ratio between 2.5:1 and 3.0:1 and a barrier or Maddock mixing section. A typical barrel profile is 180 °C, 195 °C, 200 °C, 200 °C, 195 °C with melt temperature at 200–210 °C. Measured apparent viscosity for general-purpose PLA at 210 °C is approximately 200–400 Pa·s at shear rates of 100–1000 s⁻¹; shear thinning is more pronounced than PET, so screw speed and back pressure must be limited. On a 60 mm extruder, screw speeds above 120 rpm can raise melt temperature above 220 °C via shear heating. Barrel residence time should remain below 8 min because thermal degradation above 220 °C generates lactide and discolors the melt.

Injection molding uses melt temperature 190–205 °C. Cold-runner molds are held at 25–40 °C; hot-runner and annealed parts use mold temperatures of 100–110 °C. Hydraulic hold pressure between 60 MPa and 100 MPa assists thin-wall filling, but gate dimensions below 1.0 mm may require flow simulation because the melt flow index of VG7232U is at the low-flow end of unmodified PLA. Mold shrinkage of 0.3–0.5 % per ISO 294-4:2018 requires positive sprue pull and sufficient draft. At shutdown, the barrel should be purged with LDPE at 180 °C or a PLA-specific purging compound to prevent carbonized residue.

Thermoforming of amorphous sheet is conducted at sheet surface temperature 90–110 °C. The sheet should be cooled below 40 °C before trimming to avoid edge tear. Ambient relative humidity above 60 % during edge trim or sheet storage can increase surface moisture and should be addressed with dry air curtains rather than extended predrying of finished sheet.

Before tooling is finalized, mechanical properties should be verified on specimens molded from the actual production tool because cooling rate and quenching shift the amorphous/crystalline balance. The property envelope in Table 1 applies to dry specimens at 23 °C and 50 % relative humidity after conditioning per ISO 291:2008. Values should be used for initial mold design, not as lot-specific certificates of analysis.

The annealed heat deflection temperature in Table 1 is conditional on 30 min at 100 °C and is not obtained on cold-molded parts. Without annealing, the part softens near the glass transition and loses dimensional stability under dry heat. This distinction is critical for cutlery intended for hot soup or lids on hot beverage cups; if service temperature exceeds 60 °C, the tool must incorporate annealing or the material selection should be reevaluated.

When Food-Contact and Industrial Compostability Testing Are Required as a Precondition for Market Entry

Compostability certification is a system-level property, not an intrinsic resin property. For a final article produced from VG7232U, EN 13432:2000 or ASTM D6400-19 certification requires four linked findings: chemical characterization, ultimate aerobic biodegradation, disintegration during composting, and absence of adverse effects on compost quality. Aerobic biodegradation is measured by ISO 14855-1:2012 or ASTM D5338-15; the acceptance criterion is ≥90 % conversion of organic carbon to carbon dioxide relative to the reference within 180 days. Disintegration is measured by ISO 16929:2021 or ISO 20200:2015; after 12 weeks, no more than 10 % of the original dry mass may remain on a 2 mm sieve. Ecotoxicity testing under OECD 208 requires germination rate and plant biomass to be at least 90 % of the blank compost. These thresholds define industrial composting at 58±2 °C with active aeration and moisture above 50 %.

Food-contact evaluation under European Union law starts with Regulation (EC) No 1935/2004 and Commission Regulation (EU) No 10/2011, as amended. The finished plastic article must not transfer constituents above the overall migration limit of 10 mg/dm² of food contact surface. For VG7232U, simulant selection follows the intended food type and contact time; aqueous acidic and alcoholic simulants are typically 3 % acetic acid, 10 % ethanol, and 20 % ethanol, while fatty simulants may require isooctane or 95 % ethanol substitutes. Lactic acid monomer is not assigned a harmonized specific migration limit in EU 10/2011, but lactide and oligomer fractions must be assessed as part of the overall migration and, if required, by worst-case calculation. United States compliance is established through FDA 21 CFR 174.5 and an applicable Food Contact Notification for this resin class; VG7232U is not a generic cleared resin listed in 21 CFR 177. Converters must maintain composition records and good manufacturing practice evidence under EU 2023/2006.

Home compost conditions are not equivalent to the industrial test protocols cited above. Unless a home compost certification has been issued under a recognized national program, VG7232U should not be marked home-compostable. Published data for this specific configuration in home composting and anaerobic digestion are limited.

Comparative Placement Against Blended, Filled, and Petroleum-Derived Rigid Packaging Resins

In the rigid packaging resin field, VG7232U is positioned as an unmodified PLA with high modulus and limited elongation. Under ISO 527-2:2012 at 23 °C, the grade exhibits tensile yield strength of 55–65 MPa and elongation at break of 3–6 %. PBAT-modified PLA compounds typically exceed 100 % elongation but may lose 30–50 % of tensile modulus relative to VG7232U. The property difference determines part design: VG7232U suits rigid cutlery and trays requiring bending stiffness, whereas PBAT-modified PLA is chosen for flexible films and bags.

The comparison with mineral-filled PLA is primarily thermal and rheological. Talc-filled PLA compounds can raise heat deflection temperature at 0.45 MPa by 5–15 °C over unannealed VG7232U, but they increase melt viscosity and may require mold temperatures above 100 °C to achieve consistent crystallinity. Fillers also reduce density-adjusted tensile strength and require hard-coated screws because wear increases. VG7232U contains no mineral nucleant, so its annealed heat deflection resistance relies on time-temperature exposure of the part, not on filler content.

Compared with general-purpose polystyrene, amorphous VG7232U has similar clarity in sheet form but a lower continuous service limit. Unannealed PLA softens near 55–60 °C per ISO 11357-2:2020, while GPPS retains practical rigidity to 80–90 °C in dry service. The difference is critical in hot-beverage lids or microwaveable trays. Compared with PET, VG7232U processes at lower melt temperature, 190–210 °C versus 260–280 °C for PET, but VG7232U must not enter the PET bottle reclaim stream because it causes hydrolytic defects and haze in recycled PET.

Compared with PHA packaging resins, VG7232U is structurally simpler and more rigid at room temperature, but PHA often provides broader marine or soil biodegradation behavior depending on copolymer composition. The difference in certification scope is not a single value; it must be evaluated by ASTM D6691-17 for marine degradation or ISO 17556:2019 for soil if such claims are made. Published data for this specific configuration in marine environments are limited.

Operational boundaries include relative humidity above 60 %, regrind fractions above 30 wt%, exposure to boiling water or steam, and melt residence times beyond 8 min. Each of these conditions either promotes hydrolytic degradation or accelerates lactide formation. Regrind should be dried with virgin pellets to <250 ppm moisture and kept at a ratio of ≤30 wt% unless mechanical property testing on the finished article confirms equivalent performance. Batch-to-batch control should include melt flow index per ISO 1133-1:2022 and moisture per ISO 15512:2019; an upward drift in melt flow index beyond the supplied quality window indicates either poor drying or excessive regrind addition. The material is not recommended for applications requiring repeated boiling-water exposure or long-term hot-fill above 80 °C without post-mold annealing and article-level migration testing.