Enhancing gas barrier performance of polylactic acid/lignin composite films through cooperative effect of compatibilization and nucleation
Enhancing gas barrier performance of polylactic acid/lignin composite films through cooperative effect of compatibilization and nucleation
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通过增容与成核协同作用提高聚乳酸/木质素复合膜的气体阻隔性能
DOI：
10.1002/app.50199
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发表时间：
2020-10-30
影响因子：
3
通讯作者：
Weng, Yunxuan
中科院分区：
文献类型：
--
作者：
Wang, Ningning;Zhang, Caili;Weng, Yunxuan
本研究以木质素为非均相成核剂，提高聚乳酸（PLA）的结晶度。为了提高PLA/LG复合膜的气体屏障性能，成功合成了两种接枝共聚物聚乳酸-接枝甲基丙烯酸甘油酯（PLA-g- gma）和聚乳酸-接枝聚乙二醇甲基丙烯酸甲醚（PLA-g- pegma），并分别作为增容剂改性PLA/LG复合膜的界面附着力、结晶度和力学性能。由于晶体可以作为气体扩散的障碍，聚合物基体的结晶度越高，复合膜的气体阻隔性能越好。采用广角x射线衍射和差示扫描量热法对聚乳酸基体的结晶度和晶体结构进行了表征。由于LG颗粒可以作为高效的非均相晶体成核剂，通过向PLA基体（PLA/1LG）中添加1 phr LG，可以获得约50%的氧渗透率（P-O2）降低。在PLA/LG复合材料中添加10 phr PLA-g- gma后，PLA/PLA-g- gma /LG复合膜的气体阻隔性能低于未添加相容剂的PLA/LG复合材料。此外，PLA-g- gma的加入显著提高了PLA/LG复合材料的界面附着力。因此，PLA/PLA-g- gma /3LG的拉伸强度最高，比纯PLA提高33%。在PLA/LG复合材料中加入10 phr PLA-g- pegma后，PLA-g- pegma的长线型侧链能够作为PLA的成核剂，促进PLA的结晶。因此，与纯PLA膜相比，具有3 phr LG的PLA/PLA-g- pegma /3LG膜的P-O2含量降低了约86%。
In this work, lignin was used as a heterogeneous nucleating agent to increase polylactic acid (PLA) crystallinity. To enhance the gas barrier performance of PLA/LG composite films, two graft copolymers, polylactide-graft-glycidyl methacrylate (PLA-g-GMA) and polylactide-graft-poly (ethylene glycol) methyl ether methacrylate (PLA-g-PEGMA) were successfully synthesized and separately used as compatibilizers to modify PLA/LG composite properties such as interfacial adhesion, crystallinity, and mechanical properties. Since crystallites can act as obstacles to gas diffusion, the higher the crystallinity of the polymer matrix, the better gas barrier performance of the composite film will be. The crystallinity and crystalline structure of the PLA matrix was demonstrated by wide-angle X-ray diffraction and differential scanning calorimetry results. Since LG particles can act as efficient heterogeneous crystal nucleating agents, a roughly 50% reduction in oxygen permeability (P-O2) was obtained by adding 1 phr LG to the PLA matrix (PLA/1LG). Following addition of 10 phr PLA-g-GMA to the PLA/LG composite, PLA/PLA-g-GMA/LG composite films showed lower gas barrier properties than PLA/LG composites without added compatibilizer. Moreover, the interfacial adhesion of PLA/LG composites was significantly improved after addition of PLA-g-GMA. Therefore, PLA/PLA-g-GMA/3LG showed the highest tensile strength, 33% higher than that of neat PLA. Following addition of 10 phr PLA-g-PEGMA to the PLA/LG composite, the long liner side chains of PLA-g-PEGMA were able to act as nucleating agents for PLA to promote the crystallization of PLA. Accordingly, PLA/PLA-g-PEGMA/3LG with 3 phr LG showed a roughly 86% reduction in P-O2 when compared with neat PLA film.