1. Core material properties and environmental advantages Raw material source and biodegradability: PLA (polylactic acid) is made from biomass starches such as corn and sugarcane. It is produced into lactic acid through microbial fermentation and then polymerized to form linear aliphatic polyester. Its most prominent feature is its complete biodegradability: under composting conditions, over 80% can be degraded within 8 to 25 weeks (in compliance with ISO 14855 standards), and in the natural environment, it completely decomposes into CO₂ and water within 3 to 5 years, leaving no residue and forming a carbon cycle closed loop, reducing the greenhouse effect. Physical properties: High transparency (comparable to PET and cellophane), high hardness, but relatively low initial heat resistance (heat distortion temperature 55℃) and toughness. The heat resistance can be enhanced to above 120℃ and the impact resistance can be improved through modification techniques (such as nanocellulose reinforcement, blended polycaprolactone PCL or ethylene-vinyl acetate copolymer). Biocompatibility: Applicable in the medical field, such as absorbable bone screws, surgical sutures, and drug sustained-release systems, to avoid secondary surgeries. Environmental protection attributes: Reduce reliance on petroleum resources, comply with the "plastic ban" and the "14th Five-Year Plan" for industrial green development, and contribute to the carbon neutrality goal.
2. Processing technology and technological innovation Mainstream processes Extrusion molding: By melting PLA particles through an extruder, they are cast through a die and then shaped by a cooling roller to produce continuous films or sheets (with a thickness of 0.18-1.8mm), which are suitable for packaging films, agricultural films, etc. Injection molding: For the production of complex-shaped products (such as 3D printing consumables and tableware), precise control of temperature and holding time is required to prevent material degradation. Blow molding: For manufacturing hollow containers (such as beverage bottles), it is necessary to control the melt strength and stretch ratio. Thermoforming: It is used for packaging boxes, display stands, etc. The heating temperature and time must be strictly controlled to prevent excessive softening or decomposition.
Process difficulty: PLA has poor thermal stability, and the processing temperature must be strictly controlled at 180-200℃ (to avoid high-temperature degradation). It has strong hygroscopicity and requires pre-drying treatment. The melt strength is low and needs to be improved by adding nucleating agents or modifiers.
3. Application scenarios and typical cases Packaging field: food preservation film, shopping bags, agricultural film (begins to degrade within 20 days), beverage bottles, 3D printing consumables. The transparency and barrier properties of PLA film (such as anti-mold and antibacterial) make it an ideal choice for flexible packaging of fruits and vegetables. In the medical field: surgical sutures, tissue engineering scaffolds, and drug-sustained-release microspheres, taking advantage of their biocompatibility and controllable degradation properties. Agriculture and environmental protection: Biodegradable seedling POTS, flower POTS, geotextiles, reducing plastic residues in the soil; Agricultural films naturally degrade after the end of the crop growth cycle. Industry and consumption: Automotive interior parts (such as seat covers), electronic product casings, disposable tableware (spoons, forks), textile fibers (antibacterial underwear, sportswear). Special application: PLA alumina film/aluminum-coated film enhances barrier performance through high vacuum aluminum-coating technology and is used in food composite bag-making and paper-plastic composite packaging to extend the shelf life.
4. Performance Standards and Quality control Degradation standard: Complies with ISO 14855 composting degradation standard, with a degradation rate of ≥80% within 45 days. It will completely degrade within 3 to 5 years in a natural environment. Physical properties: Tensile strength, impact strength, transparency, and barrier properties (such as oxygen/water vapor transmission rate) must meet the specific application requirements. Medical-grade PLA must pass biocompatibility tests (such as cytotoxicity and skin irritation). Environmental protection certification: Complies with RoHS and REACH standards, no halogen or harmful substance release; Passed the ISO 9001 quality management system certification.
