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Peculiar crystallization and viscoelastic properties of polylactide/polytetrafluoroethylene composites induced by in-situ formed 3D nanofiber network
Composites Part B: Engineering ( IF 13.1 ) Pub Date : 2020-08-21 , DOI: 10.1016/j.compositesb.2020.108361
Amirjalal Jalali , Jung- Hyun Kim , Ali M. Zolali , Iman Soltani , Mohammadreza Nofar , Ehsan Behzadfar , Chul B. Park

This study comprehensively investigates the development of in-situ polylactide (PLA)/polytetrafluoroethylene (PTFE) nanofibrillated composites. PLA based composites containing 1, 3 and 5 wt% PTFE were prepared by melt compounding in a twin-screw extruder. SEM images demonstrated that interconnected PTFE nanofiber networks were generated with uniform distribution throughout the PLA matrix. Melt viscoelastic properties of nanofibrillated composites were significantly improved due to the PTFE nanofiber network. This increase was even more pronounced when the PTFE content was raised from 1 to 3 wt%, which could be considered as the percolation threshold network concentration range of PTFE fibers. However, the overall viscosity of composites was lower than that of PLA when the amount of PTFE was increased to 5 wt% due to the lubricating effect of PTFE nanofibers, which could ease PLA processing. With the increase in PTFE content, the transcrystallization of PLA around PTFE was improved and the crystallization half-time was remarkably decreased. Accordingly, the PLA crystallization kinetics was enhanced. The PLA/PTFE nanocomposite extrudates were also injection molded. SEM images of the skin layer of the injection molded nanocomposites exhibited an oriented structure in which PLA chains crystallized around the PTFE nanofibrils, whereas an amorphous structure was observed for the core layer. The crystalline structure and orientation, as well as thermal properties of the injection molded PLA/PTFE nanocomposites, were assessed by wide and small-angle X-ray scattering and differential scanning calorimetry, respectively.



中文翻译:

原位形成3D纳米纤维网络诱导的聚丙交酯/聚四氟乙烯复合材料的特殊结晶和粘弹性

这项研究全面调查了原位的发展聚乳酸(PLA)/聚四氟乙烯(PTFE)纳米原纤化复合材料。通过在双螺杆挤出机中熔融配混来制备含有1、3和5重量%的PTFE的基于PLA的复合材料。SEM图像表明,生成的互连PTFE纳米纤维网络在整个PLA基质中分布均匀。由于PTFE纳米纤维网络,纳米原纤化复合材料的熔体粘弹性显着提高。当PTFE含量从1wt%增加到3wt%时,这种增加甚至更加明显,这可以被认为是PTFE纤维的渗透阈值网络浓度范围。然而,由于PTFE纳米纤维的润滑作用,当PTFE的含量增加到5 wt%时,复合材料的总粘度低于PLA,这可以简化PLA的加工过程。随着PTFE含量的增加,PLA在PTFE周围的转结晶得到改善,结晶半衰期显着减少。因此,提高了PLA结晶动力学。PLA / PTFE纳米复合材料挤出物也被注塑成型。注射成型的纳米复合材料的表皮层的SEM图像显示取向结构,其中PLA链在PTFE纳米原纤维周围结晶,而对于芯层观察到无定形结构。分别通过广角和小角X射线散射和差示扫描量热法评估了注塑PLA / PTFE纳米复合材料的晶体结构和取向以及热性能。聚四氟乙烯在聚四氟乙烯周围的转变结晶得到改善,结晶半衰期明显减少。因此,提高了PLA结晶动力学。PLA / PTFE纳米复合材料挤出物也被注塑成型。注射成型的纳米复合材料的表皮层的SEM图像显示取向结构,其中PLA链在PTFE纳米原纤维周围结晶,而对于芯层观察到无定形结构。分别通过广角和小角X射线散射和差示扫描量热法评估了注塑PLA / PTFE纳米复合材料的晶体结构和取向以及热性能。聚四氟乙烯在聚四氟乙烯周围的转变结晶得到改善,结晶半衰期明显减少。因此,提高了PLA结晶动力学。PLA / PTFE纳米复合材料挤出物也被注塑成型。注射成型的纳米复合材料的表皮层的SEM图像显示取向结构,其中PLA链在PTFE纳米原纤维周围结晶,而对于芯层观察到无定形结构。分别通过广角和小角X射线散射和差示扫描量热法评估了注塑PLA / PTFE纳米复合材料的晶体结构和取向以及热性能。注射成型的纳米复合材料的表皮层的SEM图像显示取向结构,其中PLA链在PTFE纳米原纤维周围结晶,而对于芯层观察到无定形结构。分别通过广角和小角X射线散射和差示扫描量热法评估了注塑PLA / PTFE纳米复合材料的晶体结构和取向以及热性能。注射成型的纳米复合材料的表皮层的SEM图像显示取向结构,其中PLA链在PTFE纳米原纤维周围结晶,而对于芯层观察到无定形结构。分别通过广角和小角X射线散射和差示扫描量热法评估了注塑PLA / PTFE纳米复合材料的晶体结构和取向以及热性能。

更新日期:2020-08-28
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