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该文通过静电纺丝法制备了直径范围在100nm-500nm之间的PCL(Poly(ε-caprolactone))纳米纤维。并成功使用原子力显微镜(AFM)测量了单根纳米纤维的动力学性能,发现PCL纳米纤维有显著的尺度效应,弹性模量随直径的减小而增加。为解释该现象,该文发展了包含应变梯度效应的两端固支纤维振动模型,利用该模型对PCL纳米纤维的尺寸效应进行了分析。结果显示,当材料尺度参数leff=78nm时,新模型与实验结果吻合良好。而应变梯度效应可忽略时,新的振动方程退化为经典的Euler-Bernoulli振动方程。
In this paper, PCL (poly (ε-caprolactone)) nanofibers with diameters ranging from 100nm to 500nm were prepared by electrospinning. The kinetic properties of single nanofibers were measured by atomic force microscopy (AFM). The results showed that PCL nanofibers had significant scale effect and the elastic modulus increased with the decrease of diameter. In order to explain this phenomenon, the vibrational model of fiber with both ends fixed including strain gradient was developed. The size effect of PCL nanofibers was analyzed by this model. The results show that when the material scale parameter leff = 78nm, the new model is in good agreement with the experimental results. When the strain gradient effect is negligible, the new vibration equation degenerates into the classical Euler-Bernoulli vibration equation.