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生物可降解聚合物可以在保持结构力学性能的同时可以实现碳中性,是石油基聚合物的潜在替代品.在这些聚合物中,聚乳酸(Polylactic acid,PLA)因其良好的力学性能、生物相容性和热塑性而特别有发展前景.本文利用机械脱脂纤维素纳米纤维(Cellulose nanofiber,CNF)来提高聚乳酸的力学性能,该纤维具有显著的力学性能和生物降解性.熔融沉积建模(Fused deposition modeling,FDM)是热塑性聚合物的三维打印方法之一,可以降低制造成本.本研究采用FDM法制备了机械脱脂CNF增强PLA基复合材料,并在两个打印方向(0°/90°和+45°/?45°)上研究了它们的拉伸性能,梳理了机械制备CNF增强PLA基复合材料的印刷方向与拉伸行为之间的关系.此外,利用扫描电镜研究了机械脱脂CNF增强PLA基复合材料的显微组织和断口.“,”Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures. Among these polymers,polylactic acid(PLA)is particularly promising due to its good mechanical properties,biocompatibility and thermoplasticity. In this work,we aim to enhance the mechanical properties of PLA using mechanically-defibrated cellulose nanofibers (CNFs) that exhibit remarkable mechanical properties and biodegradability. We also employ fused deposition modeling(FDM),one of the three-dimensional printing methods for thermoplastic polymers,for the low-cost fabrication of the products. Mechanically-defibrated CNF-reinforced PLA matrix composites are fabricated by FDM. Their tensile properties are investigated in two printing directions(0°/90° and+45°/?45°). The discussion about the relationship between printing direction and tensile behavoir of mechanically-defibrated CNF-reinforced PLA matrix composite is the unique point of this study. We further discuss the microstructure and fracture surface of mechanically-defibrated CNF-reinforced PLA matrix composite by scanning electron microscope.