In this research, first, ZnO nanorods were synthesized by hydrothermal method and characterized in terms of morphological and structural properties by means of field emission scanning electron microscopy, Fourier transform infrared, and X-ray diffraction techniques. Subsequently, polylactic acid/ZnO, polylactic acid/TiO2, and polylactic acid/ZnO/TiO2 nanocomposites with different percentages of nanoparticles and two different types of ZnO morphologies were prepared and their microstructural, optical, mechanical, hydrolytic degradation, and antibacterial properties were investigated. Field emission scanning electron microscopy results of polylactic acid/ZnO and polylactic acid/TiO2 samples showed a proper dispersion and nanoparticle distribution for low percentages (up to 5 wt%) and increased aggregation for the higher percentages. Besides, a large increase in the aggregation tendency was observed for combined nanoparticles (polylactic acid/ZnO/TiO2 nanocomposites). Results of the tensile test, the UV–Vis absorption tests, and the hydrolytic degradation tests of the samples showed an enhanced mechanical (approximately 55% increase in the presence of 3–5 wt% of nanoparticles) and light absorption and degradation (approximately 85% increase in the presence of 3–10 wt% of nanoparticles) for the polylactic acid by incorporating nanoparticles. It was also observed that, in addition to the quality of dispersion and distribution of nanoparticles in the polymeric matrix, the type of morphology of nanoparticles can contribute to the improvement of these properties. The cylindrical morphology of ZnO played a greater role on improving the polylactic acid mechanical properties compared to the spherical ZnO morphology (approximately 20%). On the contrary, the increased polylactic acid optical properties and degradation with ZnO spherical morphology were more pronounced (approximately 60%). Interestingly, when both ZnO and TiO2 were added, a synergistic effect in the case of UV-shielding and degradation rate and alternatively, a detrimental effect on the mechanical properties were detected. (The polylactic acid optical properties increased by about 17% and its degradation more than doubled.) Furthermore, the antibacterial activity of polylactic acid was investigated against the two Gram-positive Listeria monocytogenes and Gram-negative bacteria Escherichia coli by incorporating nanoparticles. The results indicated that as the nanoparticle percentage increases, the antibacterial activity steadily increases.

中文翻译：

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聚乳酸/ZnO/TiO2共享纳米复合材料的光学、机械和抗菌性能的制备与研究

本研究首先采用水热法合成了ZnO纳米棒，并利用场发射扫描电子显微镜、傅里叶变换红外光谱和X射线衍射技术对其形态和结构特性进行了表征。随后，制备了具有不同纳米颗粒百分比和两种不同类型 ZnO 形态的聚乳酸/ZnO、聚乳酸/TiO2 和聚乳酸/ZnO/TiO2 纳米复合材料，并研究了它们的微观结构、光学、机械、水解降解和抗菌性能。 . 聚乳酸/ZnO 和聚乳酸/TiO2 样品的场发射扫描电子显微镜结果表明，低百分比（高达 5wt%）具有适当的分散和纳米颗粒分布，而较高百分比的聚集增加。除了，观察到组合纳米颗粒（聚乳酸/ZnO/TiO2 纳米复合材料）的聚集趋势大幅增加。样品的拉伸试验、UV-Vis 吸收试验和水解降解试验的结果显示出增强的机械性能（在 3-5 wt% 的纳米颗粒存在下增加约 55%）和光吸收和降解（约 85通过掺入纳米颗粒，聚乳酸在存在 3-10 重量％纳米颗粒的情况下增加了 %。还观察到，除了纳米粒子在聚合物基质中的分散和分布质量外，纳米粒子的形态类型也有助于改善这些特性。与球形 ZnO 形态（约 20%）相比，ZnO 的圆柱形形态在改善聚乳酸机械性能方面发挥了更大的作用（约 20%）。相反，聚乳酸光学性质的增加和 ZnO 球形形态的降解更为明显（约 60%）。有趣的是，当同时添加 ZnO 和 TiO2 时，在紫外线屏蔽和降解速率的情况下会产生协同效应，或者对机械性能产生不利影响。（聚乳酸的光学特性增加了约 17%，其降解率增加了一倍以上。）此外，通过掺入纳米颗粒，研究了聚乳酸对两种革兰氏阳性单核细胞增生李斯特菌和革兰氏阴性细菌大肠杆菌的抗菌活性。