The compatibility of three different types of lignin, such as Kraft lignin, Organosolv lignin, and lignosulfonate, with PLA, in particular without the addition of any further reagents or compatibilizers, is investigated. The unmodified lignins were thoroughly characterized to establish their interaction potential in lignin-PLA composite formation. The obtained double-extruded binary systems containing 5, 10, and 15 wt % lignin in PLA were characterized in terms of chemical conversion (31 P NMR), thermal behavior (TGA, DSC), and cellular morphology (SEM). Additionally, the flexural and impact properties as well as the melt volume rate (MVR) of the extruded materials, in the form of 3D-printed bars, were analyzed, and the effect of lignin addition to PLA studied. The results revealed poor mechanical properties for the Kraft lignin-PLA blends, but higher compatibility of Organosolv lignin-PLA blends. Lignosulfonate-PLA blends showed a promising behavior for 3D-printing. A special nucleation effect, potentially useful in foaming applications, was observed in this study.

中文翻译：

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牛皮纸木质素、有机溶剂木质素和木质素磺酸盐与 PLA 在 3D 打印中的相容性

研究了三种不同类型的木质素，例如硫酸盐木质素、有机溶剂木质素和木质素磺酸盐与 PLA 的相容性，特别是在不添加任何其他试剂或增容剂的情况下。对未改性的木质素进行了彻底的表征，以确定它们在木质素-PLA 复合材料形成中的相互作用潜力。获得的双挤出二元体系在 PLA 中含有 5、10 和 15 重量％的木质素，根据化学转化率 (31 P NMR)、热行为 (TGA、DSC) 和细胞形态 (SEM) 进行表征。此外，还分析了 3D 打印棒材形式的挤出材料的弯曲和冲击性能以及熔体体积速率 (MVR)，并研究了木质素对 PLA 的影响。结果表明，牛皮纸木质素-PLA 共混物的机械性能较差，但有机溶剂木质素-PLA 混合物的兼容性更高。木质素磺酸盐-PLA 混合物在 3D 打印方面表现出良好的性能。在这项研究中观察到了一种特殊的成核效应，在发泡应用中可能有用。