采用溶液共混-熔融热压技术制备聚乳酸/热塑性聚氨酯/二氧化钛（PLA/TPU/TiO₂）复合薄膜，系统研究热塑性聚氨酯（TPU）质量分数与二氧化钛（TiO₂）添加量对复合薄膜力学性能、热稳定性、亲水性和抗紫外性能的影响。研究结果揭示了TPU弹性相与TiO₂刚性相的协同作用机制。当TPU质量分数为20%时，PLA/TPU复合薄膜的断裂强度和断裂伸长率达到平衡，分别为45.89 MPa和17.89%。在此基础上，继续添加质量分数2%的TiO₂，PLA/TPU/TiO₂复合薄膜的断裂强度进一步提升11.5%，达到51.17 MPa，而断裂伸长率提高了83.29%，达到32.79%。TiO₂的加入显著优化了PLA的结晶度和亲水性。当TiO₂质量分数为3%时，PLA/TPU/TiO₂复合薄膜的紫外线防护系数（UPF）达到87.35，且热稳定性显著增强。研究表明，TPU与TiO₂的协同作用不仅实现PLA的同步增韧和增强，还提升了PLA的热稳定性和抗紫外性能。制备的PLA/TPU/TiO₂复合薄膜兼具环保与功能化应用潜力，研究可为高性能可降解薄膜的开发提供支持。

Poly(lactic acid)/thermoplastic polyurethane/titanium dioxide (PLA/TPU/TiO₂) composite films were prepared using a solution blending-melt hot pressing technique. The effects of the mass fraction of thermoplastic polyurethane (TPU) and the addition of titanium dioxide (TiO₂) on the mechanical properties, thermal stability, hydrophilicity, and UV resistance of the composite films were systematically investigated. The results revealed the synergistic mechanism between the elastic phase of TPU and the rigid phase of TiO₂. When the mass fraction of TPU was 20%, the tensile strength and elongation at break of the PLA/TPU composite film reached a balance, with values of 45.89 MPa and 17.89%, respectively. On this basis, the addition of 2% TiO₂ further increased the tensile strength of the PLA/TPU/TiO₂ composite film by 11.5%, reaching 51.17 MPa, while the elongation at break increased by 83.29%, reaching 32.79%. The addition of TiO₂ significantly optimized the crystallinity and hydrophilicity of PLA. When the mass fraction of TiO₂ was 3%, the ultraviolet protection factor (UPF) of the PLA/TPU/TiO₂ composite film reached 87.35, and its thermal stability was significantly enhanced. The study demonstrated that the synergistic effect of TPU and TiO₂ not only achieved simultaneous toughening and strengthening of PLA but also improved its thermal stability and UV resistance. The prepared PLA/TPU/TiO₂ composite films possess both environmental friendliness and functional application potential, and the research provides support for the development of high-performance biodegradable films.