基于AFM的聚己酸内酯纳米纤维的弯曲力学性能

AFM-Based Bending Test of Electrospun PCL Nanofibers

采用原子力显微镜(AFM)对静电纺丝法制备的纳米级聚己酸内酯纤维进行了三点弯曲实验。纳米纤维收集在经光刻处理后带有U型凹槽的硅片上,凹槽的深度为10μm,待测纳米纤维的直径范围为83nm～800nm。利用原子力显微镜的探头测量纤维直径并对纤维中点施力获得纤维的力-挠度曲线,结合经典的梁弯曲理论,计算出聚己酸内酯纳米纤维的弹性模量。实验结果显示,当纤维直径减小到某一临界值时,纤维的弹性模量呈现显著增大的趋势,这说明在研究纳米尺度聚己酸内酯纤维的力学性能过程中,需要考虑其尺寸效应。

In this paper, results of an atomic force microscopy （AFM）-based 3-point bending test performed on electrospun polycaprolactone （PCL） nanofibers were reported. The fibers had diameters that range from 83 nm--800 nm and samples were collected for testing by randomly depositing them over a silicon wafer lined with 10 μm Uchannels. Using the AFM tip the precise fiber diameter and the force-deflection curve were measured, and from this information the elastic modulus of the PCL nanofibers were readily determined via the classic beam bending theory. The results show that the fibers exhibit an increasingly enhanced elastic modulus as their diameters are decreased past a threshold value. Our experiments show that it is necessary to consider the obvious size-dependent behavior in PCL fibers when studying their mechanical properties at the nano-scale level.