Zhang Zhongsen, Cao Bingyan, Jiang Ning
School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China.
School of Transportation and Vehicle Engineering, Shandong University of Technology, Zibo 255049, China.
Materials (Basel). 2023 Sep 13;16(18):6197. doi: 10.3390/ma16186197.
Polylactic acid (PLA) has been widely used in many fields because of its good biodegradability, biocompatibility, and renewability. This work studied the degradation behavior and mechanical properties of cellulose nanofiber (CNF)/PLA composites. In vitro degradation experiments of 3D-printed samples were conducted at elevated temperatures, and the degradation characteristics were evaluated by mechanical tests, gel permeation chromatography (GPC), differential scanning calorimetric (DSC), and scanning electron microscope (SEM). The results indicated that the addition of CNF (0.5 wt%) accelerated the degradation rate of PLA. The decreases in number average molecular weight (Mn) and weight average molecular weight (Mw) of composites were 7.96% and 4.91% higher than that of neat PLA, respectively. Furthermore, the tensile modulus of composites was 18.4% higher than that of neat PLA, while the strength was 7.4% lower due to poor interfacial bonding between CNF and PLA. A mapping relationship between accelerated and normal degradation showed that the degradation experienced during 60 days at 37 °C was equivalent to that undergone during 14 days at 50 °C; this was achieved by examining the alteration in Mn. Moreover, the degradation process caused a notable deformation in the samples due to residual stress generated during the 3D printing process. This study provided valuable insights for investigating the in vitro degradation behavior of 3D-printed products.
聚乳酸（PLA）因其良好的生物降解性、生物相容性和可再生性而在许多领域得到广泛应用。本工作研究了纤维素纳米纤维（CNF）/PLA复合材料的降解行为和力学性能。对3D打印样品进行了高温下的体外降解实验，并通过力学测试、凝胶渗透色谱（GPC）、差示扫描量热法（DSC）和扫描电子显微镜（SEM）对降解特性进行了评估。结果表明，添加CNF（0.5 wt%）加速了PLA的降解速率。复合材料的数均分子量（Mn）和重均分子量（Mw）的降低分别比纯PLA高7.96%和4.91%。此外，复合材料的拉伸模量比纯PLA高18.4%，而强度由于CNF与PLA之间的界面结合不良而降低了7.4%。加速降解与正常降解之间的映射关系表明，在37℃下60天内经历的降解相当于在50℃下14天内经历的降解；这是通过检查Mn的变化实现的。此外，由于3D打印过程中产生的残余应力，降解过程导致样品出现明显变形。本研究为研究3D打印产品的体外降解行为提供了有价值的见解。
