目的 为了提高聚乳酸材料的力学性能和气体阻隔性，选择二氧化硅为共混材料，通过改变二氧化硅的粒径和含量，研究SiO2对SiO2/PLA复合膜性能的影响。方法 用流延法制备二氧化硅/聚乳酸(SiO2/PLA)复合膜。采用力学性能测试、结晶性测试、热稳定测试和透氧、透水蒸汽测试等分析手段对制备的复合膜进行力学性和阻隔性的表征。结果 在PLA材料中添加适量的SiO2对复合膜的拉伸强度和弹性模量会有增强作用，并且粒径越小，增强效果越明显;粒径为50 nm，质量分数为2%时复合膜表现出更佳的力学性能。同时，随着SiO2含量的增加，氧气透过系数呈先降低后升高的趋势，在SiO2质量分数为2%时透过系数最小，复合膜的氧气阻隔性最好;不同粒径不同含量的SiO2透湿性测试结果表明，SiO2粒径为50 nm，质量分数为2%时复合膜的阻隔性效果最好。结论 二氧化硅的加入能够提升聚乳酸的弹性模量和阻隔性，并且二氧化硅的粒径和不同添加量对复合膜的性能有很大影响。

The work aims to study the effect of different SiO2 contents and particle sizes on SiO2/PLA composite film. SiO2 was used as the additive to prepare silica/polylactic acid (SiO2/PLA) by tape casting method. The mechanical properties and barrier properties of the composite films were characterized by mechanical properties test, crystallinity test, heat stability test, oxygen permeability test and water vapor permeability test. Appropriate amount of SiO2 in PLA material enhanced the tensile strength and elastic modulus of composite films, and the smaller the particle size was, the more obvious the strengthening effect was. The mechanical properties of the composite films were better when the particle size was 50 nm and the content was 2%. At the same time, with the increase of SiO2 content, the oxygen permeability coefficient firstly decreased and then increased. When the SiO2 content was 2%, the oxygen permeability coefficient was the minimum and the oxygen barrier properties of the composite films were the best. The moisture permeability test results of SiO2 with different particle sizes and contents showed that the barrier properties of the composite films were the best when the SiO2 particle size was 50 nm and the content was 2%. In a word, the addition of SiO2 can improve the mechanical properties and barrier properties of PLA, and the difference in particle size and addition amount of silica has a great influence on the properties of the composite films.