In recent years, with the increasing global demand for plastic pollution control and low-carbon development, research on biodegradable polylactic acid (PLA) has continued to deepen, covering multiple directions including raw material diversification, molecular structure regulation, performance optimization, processing technology innovation, and degradation mechanism analysis. Breakthroughs in material design, process upgrading, and application expansion are reshaping the path of PLA's transformation from laboratory results to large-scale, functional industrial applications, demonstrating broad development prospects.
Regarding raw materials and synthesis processes, research has expanded from traditional starchy grain crops such as corn and sugarcane to non-grain biomass and industrial by-products. Using lignocellulose raw materials such as straw, rice husks, and sawdust, a technical route combining acid/alkali pretreatment, enzymatic hydrolysis, and microbial fermentation can effectively convert them into lactic acid, alleviating the conflict between grain production and land use and reducing raw material costs. Meanwhile, research on lactic acid synthesis based on carbon dioxide and microbial electrochemical systems has made phased progress, providing new ideas for constructing carbon-neutral or even carbon-negative raw material systems. In the polymerization process, the application of continuous flow reactors and novel, highly efficient catalysts (such as tin-based, zinc-based, and organic catalysts) has improved the yield and polymerization rate of lactide, and significantly suppressed the discoloration and broadening of molecular weight distribution caused by side reactions.
Molecular structure and performance modification are current research focuses. The shortcomings of pure PLA in terms of heat resistance, toughness, and controllable degradation have prompted researchers to improve performance through copolymerization, blending, and nanocomposites. Block or random copolymerization with biodegradable units such as caprolactone (PCL) and glycolic acid (GA) can adjust crystallinity, melting point, and degradation rate, enabling materials to meet the rapid degradation requirements of disposable packaging as well as structural components requiring longer service lives. The introduction of functional fillers such as nanocellulose, montmorillonite, and graphene not only improves mechanical strength and barrier properties but also endows PLA with certain antibacterial, conductive, or flame-retardant properties. Furthermore, by combining L-PLA and D-PLA using stereocomplexation technology, a crystal structure with a melting point as high as 220℃ can be obtained, significantly improving heat resistance and dimensional stability.
In the field of processing and application research, researchers are dedicated to optimizing the matching between processing window and product performance. By controlling melt rheological behavior and introducing plasticizers or processing aids, the melt strength and thermal stability of PLA in injection molding, extrusion, and blown film processes have been improved, reducing thermal degradation and yellowing. At the application level, high-transparency, high-strength PLA films have been demonstrated in food packaging and agricultural covering materials; PLA-based fibers, through optimized spinning processes, can be used to produce clothing and nonwoven fabrics that combine comfort and biodegradability; in the medical field, research on absorbable fracture internal fixation devices and drug delivery carriers continues to advance, utilizing their biocompatibility and controllable degradation cycles to meet personalized clinical needs.
Research on degradation mechanisms and evaluation methods is also continuously deepening. The academic community has established more refined in vitro simulations and in vivo experimental models, revealing the influence of temperature, pH, microbial communities, and sample morphology on the degradation rate of PLA. Simultaneously, research on the applicability of standardized testing methods (such as the ISO 14855 series and ASTM D6400) under different climatic and composting conditions provides data support for the development of regional degradation performance evaluation systems.
Overall, research in the PLA field has moved from single-material synthesis to multidisciplinary integration, encompassing areas such as biochemical engineering, polymer physics, processing engineering, and environmental science. These advances have not only significantly broadened the performance boundaries and application scenarios of PLA but also laid a solid foundation for solving traditional plastic pollution and realizing a circular bioeconomy. In the future, with the further maturation of technologies such as non-grain raw material utilization, functional customization, and controllable degradation, PLA is expected to achieve efficient replacement of petroleum-based plastics in a wider range of industrial and consumer sectors.