As an important bio-based biodegradable plastic, the widespread application of polylactic acid (PLA) relies heavily on a scientific and rigorous technical specification system.These specifications not only provide a basis for raw material production, product processing, performance evaluation, and environmental disposal, but also play a fundamental role in ensuring product quality, maintaining market order, and achieving environmental benefits. Currently, a multi-dimensional framework covering raw material requirements, performance indicators, processing control, degradation certification, and safety compliance has been formed around PLA, and it continues to develop and improve at both international and domestic levels.
Regarding raw materials and production specifications, the technical specifications first clarify the source and purity requirements of lactic acid. Lactic acid used for polymerization should meet the corresponding food-grade or industrial-grade standards. The limits for heavy metals, residual solvents, and harmful impurities must be strictly controlled to avoid safety and performance hazards in subsequent polymerization and product applications. As a key intermediate in polymerization, lactide's optical purity and racemic ratio directly affect the crystallization behavior and mechanical properties of PLA. Therefore, standards typically stipulate a lactide purity of no less than 99.5% and limit monomer residue levels to ensure stable polymerization and controllable molecular weight.
Product performance specifications vary depending on the application. For general-purpose PLA, tensile strength, flexural modulus, melt flow rate, and heat distortion temperature are generally defined within specific ranges in national or industry standards to balance processing adaptability and performance. For food contact applications, standards additionally require total migration and specific migrations (such as monomeric lactic acid and catalyst residues) to be below safety limits and comply with relevant food packaging material regulations. In the medical field, high-purity PLA must meet biocompatibility standards; degradation products must not trigger toxic or immune responses. This is typically governed by biocompatibility assessment standards such as ISO 10993.
Processing and quality control specifications emphasize the feasibility and traceability of process parameters. Because PLA is sensitive to moisture, the drying process must be carried out according to specifications to ensure that the moisture content of the raw material is below the specified threshold (commonly ≤0.02%) before processing. Processing temperature, screw speed, mold temperature, and other parameters should be within the recommended range, supplemented by online monitoring and recording to prevent thermal degradation leading to performance deterioration. Finished product inspection should include appearance, dimensional tolerances, physical and mechanical properties, and, if necessary, optical property testing to ensure batch-to-batch consistency.
Degradation performance and environmental disposal standards are the core aspects that distinguish PLA from traditional plastics. Internationally recognized industrial composting degradation standards (such as ISO 14855, EN 13432, and ASTM D6400) specify that under specific temperature (typically 58±2℃), humidity, and aerobic conditions, the material must achieve a specified biodegradation rate (often above 60% carbon dioxide release) and degree of disintegration (more than 90% of fragments smaller than 2 mm) within a certain period. Simultaneously, the standards set limits on heavy metal content to ensure that compost products can be safely used for soil amendment. For degradation behavior in non-compostable environments (such as soil and seawater), current assessments are mostly based on reference methods, and relevant standards are still being refined.
Labeling and compliance requirements are also incorporated into the technical specification system. PLA products that meet specific degradation standards can have corresponding certification marks (such as "compostable" or "for industrial composting") affixed to their packaging or the product itself, but must be tested by a third-party organization and obtain a certificate. Labeling should include material type, degradation conditions, applicable scenarios, and production information to facilitate recycling and consumer identification. Furthermore, import and export trade must meet the regulatory requirements of the target market, such as the EU's REACH regulation and the US FDA's food contact materials regulations, requiring companies to establish compliance files and supply chain management.
Overall, PLA's technical specifications focus on material safety, reliable performance, and controllable degradation, covering the entire lifecycle from raw materials to waste disposal. With the expansion of its application scope and increasingly stringent environmental policies, the specification system will continue to be refined and updated, providing clear technical guidance for producers and laying a solid foundation for market supervision and public trust, thereby promoting a greater role for PLA in the sustainable materials system.