目的 通过研究聚苯乙烯薄膜不同深度下的加载力曲线，分析得到其随着深度的不同而导致测量硬度和模量的差异，研究聚苯乙烯薄膜表面粘弹性行为，从而为高分子薄膜受限效应的理论和应用探索提供参考和借鉴。方法 采用纳米压痕方法对聚苯乙烯薄膜样品（厚度约500 nm）进行了系列纳米压痕测量与分析。结果 加载速率较低时，其加载曲线与P-h2关系会发生不同程度的偏离。加载速率为0.01、0.02、0.03、0.06、0.1 mN/s时，P-h2关系中的指数从1.609逐渐增大到1.628。通过在最大载荷时保载60 s，得到了压入深度随时间变化的关系，进而计算得到蠕变柔量，并根据Zener模型拟合得到压入深度为300~400 nm时，薄膜样品存在具有不同粘弹性的两种结构。而根据不同压入深度的卸载曲线，得到样品的硬度和折合弹性模量都在压入深度约为200~400 nm的区域存在粘弹性的非均匀现象。结论 在不同压入深度处存在两种不同的粘弹性结构，根据当前人们普遍接受的高分子薄膜层模型，这两种结构分别对应聚苯乙烯薄膜样品的自由表面层和本体层。

The work aims to analyze influences of depth on hardness and elastic modules by studying loading curve of polystyrene films at different depth, and provide reference for theoretical and application exploration of polymer films confinement effect by studying surface viscoelastic behavior of polystyrene films. Series nanoindentation measurement and analysis were performed to a polystyrene film sample (nearly 500 nm thick) in the method of nanoindentation. The relationship between loading curve and P-h2 varied to different degree at low loading rate. At the loading rate of 0.01 mN/s, 0.02 mN/s, 0.03 mN/s, 0.06 mN/s and 0.1 mN/s, index in P-h2 relationship increased from 1.609 to 1.628 gradually. Relationship between indentation depth and time was obtained, and creep compliance was calculated by holding the maximum load for 60 s. According to Zener model fitting, there were two different viscoelastic structures in the film sample at the indentation depth of 300~400 nm. Moreover, according to unloading curves at different indentation depth, viscoelasticity of sample hardness and reduced elasticity modulus was not uniform in the area with indentation depth of nearly 200~400 nm. There are two different viscoelastic structures at different indentation depth. Widely accepted polymer film model shows that the two structures correspond to free surface layer and bulk layer of polystyrene film sample, respectively.