Makri Sofia P, Xanthopoulou Eleftheria, Klonos Panagiotis A, Grigoropoulos Alexios, Kyritsis Apostolos, Deligkiozi Ioanna, Zoikis-Karathanasis Alexandros, Nikolaidis Nikolaos, Bikiaris Dimitrios, Terzopoulou Zoi
Creative Nano PC, 43 Tatoiou, Metamorfosi, 14451 Athens, Greece.
Laboratory of Polymer and Colors Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
Polymers (Basel). 2024 Dec 19;16(24):3542. doi: 10.3390/polym16243542.
The present work focuses on the synthesis and characterization of biobased lignin-poly(lactic) acid (PLA) composites. Organosolv lignin, extracted from beechwood, was used as a filler at 0.5, 1.0, and 2.5 wt% loadings, with ultrasonication reducing the lignin particle size to ~700 nm. The PLA-lignin composites were prepared via in situ ring-opening polymerization (ROP) of L-lactide in the presence of lignin. This method ensured uniform lignin dispersion in the PLA matrix due to grafting of PLA chains onto lignin particles, preventing aggregation. Strong polymer-filler interactions were confirmed through spectroscopic analysis (FTIR and XPS) and their effects on static and dynamic glass transitions (DSC). These interactions enhanced mechanical properties, including a two-fold increase in tensile strength and elongation at 1 wt% lignin. Crystallization was suppressed due to shorter PLA chains, and a 15% drop in dynamical fragility was observed via Broadband Dielectric Spectroscopy (BDS). Antioxidant activity improved significantly, with PLA-2.5% ultrasonicated organosolv lignin reducing DPPH• content to 7% after 8 h, while UV-blocking capability increased with lignin content.
本工作聚焦于生物基木质素-聚乳酸（PLA）复合材料的合成与表征。从山毛榉木中提取的有机溶剂木质素被用作填料，负载量分别为0.5 wt%、1.0 wt%和2.5 wt%，通过超声处理将木质素粒径减小至约700 nm。PLA-木质素复合材料是在木质素存在的情况下，通过L-丙交酯的原位开环聚合（ROP）制备的。由于PLA链接枝到木质素颗粒上，这种方法确保了木质素在PLA基体中均匀分散，防止了团聚。通过光谱分析（FTIR和XPS）证实了聚合物与填料之间存在强相互作用，以及它们对静态和动态玻璃化转变（DSC）的影响。这些相互作用增强了力学性能，包括在1 wt%木质素含量时拉伸强度和伸长率提高了两倍。由于PLA链较短，结晶受到抑制，通过宽带介电谱（BDS）观察到动态脆性下降了15%。抗氧化活性显著提高，PLA-2.5%超声处理的有机溶剂木质素在8小时后将DPPH•含量降低至7%，同时紫外线阻挡能力随木质素含量增加而提高。
