关键词: 聚乳酸, 马来松香, 分子动力学模拟, 改性, 增韧

Abstract: With increasing global environmental awareness and the pursuit of sustainable development pathways, the demand for biobased materials has surged significantly. Poly(lactic acid) (PLA), a prominent biodegradable plastic, has shown great potential across various sectors due to its favorable biocompatibility and degradability. However, PLA's inherent brittleness remains a critical barrier to its widespread adoption. Therefore, developing effective toughening technology is essential to expanding PLA's application fields and enhancing its market competitiveness. In this context, maleated rosin (MR), a naturally abundant resource, offers a promising avenue for PLA toughening modifications due to its unique chemical structure and superior physical properties, warranting thorough research and exploration.
This study systematically examines the toughening effect of MR on PLA through a combination of theoretical modeling and experimental validation. Initially, molecular dynamics simulations are employed to investigate how planar MR molecules influence the arrangement and stacking of PLA molecules in the molten state. By adjusting the PLA/MR blend ratio and analyzing the Flory-Huggins interaction parameters and radial distribution functions, the optimal compatibility range (PLA/MR blend ratio between 2/8 and 7/3) is identified. Further analysis of dynamic rheological behavior, thermal properties, and crystallinity confirms the excellent compatibility between linear PLA and planar MR during the blending extrusion process. The experimentally prepared PLA/MR blended fibers exhibit smooth surfaces and uniform fineness. Notably, with an MR content of 20%, the blended fibers maintain tensile strength while exhibiting a substantial increase in elongation at break by approximately 2.3 times and a remarkable enhancement in rupture work by roughly 193.6 times, underscoring the significant toughening effect of MR on PLA fibers. The research not only introduces a novel approach for toughening PLA but also highlights the immense potential of natural products in developing high-performance biobased materials. 
Future studies could explore the composite effects of MR with other biobased or biodegradable materials to develop more diversified high-performance biocomposites. Additionally, optimizing the blending process parameters to enhance production efficiency and reduce costs is crucial for advancing the commercial application of PLA/MR blended fibers. Moreover, investigating the toughening mechanism of MR to provide theoretical guidance for the modification of other biobased materials is an important direction for future research. In the context of increasingly stringent environmental regulations and growing consumer demand for sustainable products, PLA/MR blended fibers have vast potential applications in packaging, textiles, medical fields, and beyond.

Key words: polylactic acid, maleated rosin, molecular dynamics simulation, modification, toughening