Kraft lignin has been widely investigated for the production of composite plastics by blending with different synthetic polymers. In the present study, softwood kraft lignin‐polyethylene (PE) composites are produced by extrusion. The change in lignin structure during the extrusion has been investigated and the influences of the lignin structure change on the properties and recyclability of the composites have been investigated. Extrusion reduces the content of functional groups in lignin (especially aromatic OH group) and decreases its glass transition temperature, but increases its weight‐average molecular weight and polydispersity index. In the lignin‐PE composites, lignin and PE only blend at the macroscopic level and there is no intermolecular interaction between them. Because extrusion reduces T_g and particle size of lignin, a lower temperature is needed to reprocess the lignin‐PE composites. These recycled composites have similar thermal properties, but enhanced mechanical properties. This work shows that lignin can be used as a potential component to reduce the usage of synthetic polymers, thus partially eliminating white pollution.

中文翻译：

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挤出过程中木质素结构变化对木质素-聚乙烯热塑性复合材料性能和回收率的影响

牛皮纸木质素已被广泛研究用于通过与不同的合成聚合物共混来生产复合塑料。在本研究中，软木牛皮纸木质素-聚乙烯（PE）复合材料是通过挤出生产的。研究了挤出过程中木质素结构的变化，并研究了木质素结构变化对复合材料性能和可回收性的影响。挤出减少了木质素中的官能团（特别是芳香族羟基）的含量，降低了其玻璃化转变温度，但增加了其重均分子量和多分散指数。在木质素-PE复合材料中，木质素和PE仅在宏观水平混合，它们之间没有分子间的相互作用。因为挤压降低了T _g和木质素的粒径，需要较低的温度来重新处理木质素-PE复合材料。这些回收的复合材料具有相似的热性能，但机械性能增强。这项工作表明，木质素可以用作减少合成聚合物用量的潜在成分，从而部分消除白色污染。