The injection-molding grade designated FC 60010 is a crystallized, compostable polylactic acid formulation supplied for conventional screw plasticization. The name “crystallized” describes the nucleated crystallization behavior of the material in the molded part, not a pellet that has been thermally annealed during production. The grade is differentiated from amorphous PLA by a heterogeneous nucleator package that accelerates lamellar growth, permitting ejection at higher solidification levels and reducing cooling-stage hold time. Processing begins with desiccant drying to a residual moisture ceiling of 250 ppm, determined by Karl Fischer titration, to suppress random ester hydrolysis in the melt. Melt temperature at the nozzle is typically maintained between 190 °C and 230 °C; mold temperature for crystalline shell development is commonly 100 °C to 110 °C, although induction-heated or variothermal tool surfaces may be used to decouple surface crystallization from core cooling. Under ISO 1133-1, melt flow index for this grade is defined by the supplier’s certificate of analysis; fast-crystallizing injection-molding PLAs in this category generally fall between 8 g/10 min and 30 g/10 min at 190 °C with a 2.16 kg load. Compostability is evaluated under industrial composting conditions according to EN 13432 and ASTM D6400; compliance is formulation-specific and must be confirmed on the final molded article. Regulatory status under REACH (EC) No 1907/2006 and RoHS 2011/65/EU is supplier-specific and must be verified on the safety data sheet for the lot in use.

Why Is Drying Control the Primary Defect Gate for FC 60010?

Poly(lactic acid) is susceptible to hydrolysis above its melt temperature, and the rate of chain scission is governed by residual moisture, residence time, and local barrel temperature. In production-scale injection molding with single-screw units having L/D ratios from 20:1 to 24:1, pellets entering the feed throat above 250 ppm moisture routinely produce splay, silver streaking, reduced weld-line strength, and part embrittlement. Desiccant-wheel dryers with a dew point of −40 °C or lower are specified; drying at 80 °C for 4 h is the standard starting condition. If ambient relative humidity exceeds 60 %, the drying time is extended to 6 h or hopper residence is staged to prevent re-moisture uptake. Closed conveying from dryer to feed throat is recommended because dried PLA can re-absorb surface moisture within 30 min in humid plant air.

The process conflict is not simply under-drying. Over-drying at hopper temperatures above 100 °C can cause pellet surface tackiness, bridging, and feed instability, while also inducing thermal yellowing of the nucleated compound. The practical operating band is therefore narrow: moisture must be below 250 ppm, but hopper temperature should not exceed 100 °C unless the dryer supplier has validated anti-stick airflow. In hot-runner tools, residual moisture levels above 400 ppm are commonly associated with nozzle drool and screw-recovery variation, while levels below 100 ppm produce stable shot weights and surface finish. Published data for this specific grade’s hydrolysis kinetics is limited; general PLA hydrolysis literature reports a measurable increase in melt flow index and loss of tensile strength after multiple heat histories, with the effect amplified when melt residence time exceeds 5 min at 230 °C.

Tool-Side Crystallinity Governs the Usable Heat Deflection Temperature

The fast-crystallizing architecture of FC 60010 alters the relationship between mold temperature, cycle time, and heat deflection temperature. In amorphous PLA, the glass transition at 55 °C to 60 °C limits the heat deflection temperature under 0.45 MPa to approximately 50 °C to 55 °C unless annealing is performed. In nucleated, crystallized PLA systems, the heat deflection temperature can rise above 90 °C and, with sufficient mold-side crystallinity, reach 100 °C to 130 °C under ISO 75-2 Method B. The mechanism is not solely additive content; it is the crystalline volume fraction and lamellar continuity formed during cooling at the tool wall. Differential scanning calorimetry under ISO 11357-1 typically shows a cold-crystallization exotherm between 95 °C and 110 °C for standard PLA, while fast-crystallizing grades shift the crystallization peak earlier and narrow the processing gap between melt solidification and crystallization onset.

The critical threshold is mold surface temperature. If the tool is run at a conventional chilled-water temperature of 20 °C to 40 °C, the part freezes largely amorphous and the high-heat benefit of the crystallized grade is lost; ejected parts may also exhibit post-mold shrinkage if crystallization continues later at temperatures above 60 °C. If the mold is run too hot, above 120 °C, ejection can become difficult due to reduced modulus above the glass transition and longer cooling time. The recommended starting range of 100 °C to 110 °C for FC 60010 is therefore a narrow processing window. Tools with conformal cooling or variothermal surface heating can achieve crystalline skin layers without fully heating the core, reducing overall cycle time. Crystallinity measurement on molded parts can be performed by ISO 11357-3 or by density gradient column; polarized light microscopy on microtomed sections is used to assess skin-core morphology.

The table is a comparative range summary from published PLA processing literature and is not a substitute for grade-specific acceptance limits; the supplier’s certificate of analysis governs lot release.

Compared with standard amorphous injection-molding PLA, FC 60010 is selected where the molded article must withstand brief exposure above 60 °C or where cycle time reduction through crystallization-induced ejection stiffness is required. Standard PLA grades are often run at mold temperatures below 40 °C to minimize stickiness, but the resulting parts possess low crystallinity and low heat distortion; they may require post-mold annealing at 80 °C to 100 °C for 30 min or longer to increase crystallinity. Fast-crystallizing grades replace some of that annealing burden by nucleating crystallization during mold residence, but they do not eliminate the mold-temperature requirement. Compared with PLA/PBAT or PLA/PHA blends, FC 60010 exhibits higher modulus and lower elongation at break, making it more similar to rigid polystyrene or filled polypropylene in handling, but with compostability tied to EN 13432 disintegration rather than oxo-degradation. Target applications include rigid packaging inserts, single-use cutlery, cosmetic closures, plant pots, and short-life technical housings where industrial composting is the intended end-of-life route.

Compostability and Regulatory Compliance Matrix

Industrial compostability is not a single threshold but a linked set of biodegradation, disintegration, ecotoxicity, and heavy-metal limits. The grades of PLA used in injection molding are evaluated under EN 13432 for the European market and ASTM D6400 for the North American market. Certification is typically issued for the specific formulation and thickness range tested; it does not automatically extend to all colors, fillers, or processing aids added downstream. The following matrix summarizes the principal test categories and their corresponding reference methods.

When Non-Composting Exposure Exceeds 55°C in Humid Service

Although crystallized PLA exhibits elevated heat deflection temperature and improved stiffness retention near the glass transition, the material is not a hydrolysis-resistant engineering polymer. Continuous service above 55 °C in high-humidity or aqueous environments can initiate ester hydrolysis at rates that accelerate with temperature and pH. The operational boundary is relevant for hot beverage accessories, dishwasher-load service, or automotive interior parts near heat sources. If a non-composting application requires sustained exposure above 60 °C under moisture, published data for this specific configuration is limited and the final part must be tested under ISO 62 moisture absorption and aged tensile retention according to ISO 527-2 after exposure. The grade should not be combined with amine-based additives, residual amines from colorants, or high-alkalinity fillers that can catalyze ester chain scission. Acidic conditions below pH 4 and alkaline conditions above pH 9 similarly reduce service life. For food-contact articles, migration testing on the actual part under EU Regulation (EU) No 10/2011 is required; material certification alone does not clear the finished article.

Molding of the grade into thin-wall sections below 1 mm may require elevated injection velocities and higher mold temperatures to prevent premature freeze-off, but shear heating in gates and runners can raise local melt temperature beyond the recommended 230 °C if screw recovery is too aggressive. The material is not intended for microwave reheating, oven use, or continuous hot-fill above 85 °C unless a functional barrier or secondary support structure is used. Post-mold annealing of amorphous skin layers can improve heat resistance, but uncontrolled annealing in a hot room above 60 °C can generate dimensional warpage. Tool designers should validate shrinkage using ISO 294-4 on a cavity-pressure-controlled molding machine before committing to multi-cavity tooling.