Azevedo Juliana V C, Ramakers-van Dorp Esther, Grimmig Roman, Hausnerova Berenika, Möginger Bernhard
Faculty of Technology, Tomas Bata University in Zlín, Vavreckova 275, 760 01 Zlín, Czech Republic.
Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg, von Liebig Str. 20, 53359 Rheinbach, Germany.
Polymers (Basel). 2022 May 10;14(10):1939. doi: 10.3390/polym14101939.
Process-induced changes in the morphology of biodegradable polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) blends modified with various multifunctional chain-extending cross-linkers (CECLs) are presented. The morphology of unmodified and modified films produced with blown film extrusion is examined in an extrusion direction (ED) and a transverse direction (TD). While FTIR analysis showed only small peak shifts indicating that the CECLs modify the molecular weight of the PBAT/PLA blend, SEM investigations of the fracture surfaces of blown extrusion films revealed their significant effect on the morphology formed during the processing. Due to the combined shear and elongation deformation during blown film extrusion, rather spherical PLA islands were partly transformed into long fibrils, which tended to decay to chains of elliptical islands if cooled slowly. The CECL introduction into the blend changed the thickness of the PLA fibrils, modified the interface adhesion, and altered the deformation behavior of the PBAT matrix from brittle to ductile. The results proved that CECLs react selectively with PBAT, PLA, and their interface. Furthermore, the reactions of CECLs with PBAT/PLA induced by the processing depended on the deformation directions (ED and TD), thus resulting in further non-uniformities of blown extrusion films.
本文介绍了用各种多功能扩链交联剂（CECL）改性的可生物降解聚己二酸对苯二甲酸丁二醇酯（PBAT）和聚乳酸（PLA）共混物在加工过程中诱导的形态变化。对吹塑薄膜挤出制备的未改性和改性薄膜的形态，在挤出方向（ED）和横向方向（TD）进行了研究。虽然傅里叶变换红外光谱（FTIR）分析仅显示出小的峰位移，表明CECLs改变了PBAT/PLA共混物的分子量，但对吹塑挤出薄膜断裂表面的扫描电子显微镜（SEM）研究揭示了它们对加工过程中形成的形态有显著影响。由于吹塑薄膜挤出过程中剪切和拉伸变形的共同作用，相当多的球形PLA岛部分转变为长纤维，如果缓慢冷却，这些长纤维倾向于分解为椭圆形岛链。将CECL引入共混物中改变了PLA纤维的厚度，改善了界面粘附，并将PBAT基体的变形行为从脆性转变为韧性。结果证明，CECLs与PBAT、PLA及其界面发生选择性反应。此外，加工过程中CECLs与PBAT/PLA的反应取决于变形方向（ED和TD），从而导致吹塑挤出薄膜进一步不均匀。
