1] Department of Materials Science, University of Patras, Rio Patras, 26504 (Greece) [2] Institute of Chemical Engineering Sciences, Foundation of Research and Technology-Hellas (FORTH/ICE-HT), Stadiou Street, Platani, Patras Acahaias, 26504 (Greece).
Institute of Chemical Engineering Sciences, Foundation of Research and Technology-Hellas (FORTH/ICE-HT), Stadiou Street, Platani, Patras Acahaias, 26504 (Greece).
Sci Rep. 2014 Jun 12;4:5271. doi: 10.1038/srep05271.
Exfoliated monolayer graphene flakes were embedded in a polymer matrix and loaded under axial compression. By monitoring the shifts of the 2D Raman phonons of rectangular flakes of various sizes under load, the critical strain to failure was determined. Prior to loading care was taken for the examined area of the flake to be free of residual stresses. The critical strain values for first failure were found to be independent of flake size at a mean value of -0.60% corresponding to a yield stress up to -6 GPa. By combining Euler mechanics with a Winkler approach, we show that unlike buckling in air, the presence of the polymer constraint results in graphene buckling at a fixed value of strain with an estimated wrinkle wavelength of the order of 1-2 nm. These results were compared with DFT computations performed on analogue coronene/PMMA oligomers and a reasonable agreement was obtained.
剥离的单层石墨烯薄片嵌入聚合物基质中，并在轴向压缩下进行加载。通过监测不同尺寸矩形薄片在负载下的 2D 拉曼声子的位移，确定了失效的临界应变。在加载之前，需要确保薄片的被检查区域没有残余应力。首次失效的临界应变值与薄片尺寸无关，平均值为-0.60%，对应屈服应力高达-6 GPa。通过将欧拉力学与文克勒方法相结合，我们表明，与空气中的屈曲不同，聚合物约束的存在导致石墨烯在固定应变下发生屈曲，估计波纹的波长约为 1-2nm。将这些结果与在模拟 coronene/PMMA 低聚物上进行的 DFT 计算进行了比较，得到了合理的一致性。
