Combining adhesive contact mechanics with a viscoelastic material model to probe local material properties by AFM
Combining adhesive contact mechanics with a viscoelastic material model to probe local material properties by AFM
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DOI：
10.1039/c7sm02057k
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发表时间：
2018-01-07
期刊：
影响因子：
3.4
通讯作者：
Hirn, Ulrich
中科院分区：
文献类型：
--
作者：
Ganser, Christian;Czibula, Caterina;Hirn, Ulrich
粘弹性性能的测量通常使用基于探针的技术，如纳米压痕（NI）和原子力显微镜（AFM）。然而，这些方法很少得到证实。在本文中，我们提出了一种将接触力学与由弹簧和阻尼器组成的粘弹性模型（VEM）相结合的方法。我们进一步展示了如何使用该模型来确定基于探针技术记录的蠕变曲线的粘弹性特性。我们着重于使用标准线性实体模型和广义2阶Maxwell模型。该方法的工作范围为0.01 Hz ~ 1hz。我们的方法适用于粗糙表面，通过材料的塑性预变形提供一个确定的接触面积。同样的程序用于评估基于AFM的测量以及对由聚（甲基丙烯酸甲酯）和聚碳酸酯制成的聚合物样品进行的NI测量。然后将这些测量结果与在相同样品上进行的拉伸蠕变试验所获得的结果进行比较。发现拉伸试验结果与原子力显微镜法和NI法的结果有很大的不同。AFM结果与NI结果之间的相似性表明，所提出的方法能够产生与NI相当的结果，但具有AFM成像可能性的优势。此外，所有三种方法都可以通过各自的粘弹性特性来明确区分PC和PMMA。
Viscoelastic properties are often measured using probe based techniques such as nanoindentation (NI) and atomic force microscopy (AFM). Rarely, however, are these methods verified. In this article, we present a method that combines contact mechanics with a viscoelastic model (VEM) composed of springs and dashpots. We further show how to use this model to determine viscoelastic properties from creep curves recorded by a probe based technique. We focus on using the standard linear solid model and the generalized Maxwell model of order 2. The method operates in the range of 0.01 Hz to 1 Hz. Our approach is suitable for rough surfaces by providing a defined contact area using plastic pre-deformation of the material. The very same procedure is used to evaluate AFM based measurements as well as NI measurements performed on polymer samples made from poly(methyl methacrylate) and polycarbonate. The results of these measurements are then compared to those obtained by tensile creep tests also performed on the same samples. It is found that the tensile test results differ considerably from the results obtained by AFM and NI methods. The similarity between the AFM results and NI results suggests that the proposed method is capable of yielding results comparable to NI but with the advantage of the imaging possibilities of AFM. Furthermore, all three methods allowed a clear distinction between PC and PMMA by means of their respective viscoelastic properties.