Local buckling behavior of multi-walled carbon nanotubes encapsulating C60 fullerenes
Local buckling behavior of multi-walled carbon nanotubes encapsulating C60 fullerenes
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DOI：
10.1016/j.cartre.2023.100269
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发表时间：
2023-05
期刊：
影响因子：
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通讯作者：
Masa Nishimura;Masaya Hatta
中科院分区：
文献类型：
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作者：
Masa Nishimura;Masaya Hatta
碳纳米管(CNTs)具有中空的结构和高的长径比。一般情况下，轴向压缩下的屈曲取决于碳纳米管的尺寸和手性以及包裹在中空空间中的材料。在这项研究中，我们对(10，10)，(17，17)和(28，28)单壁碳纳米管(SWCNTs)和对应的五壁碳纳米管(5WCNTs)进行了压缩分子动力学模拟，每一种SWCNT都作为最内层，有和没有包裹的C60。结果表明，随着碳纳米管直径的增大，屈曲应力减小。插入C60后，具有(17，17)和(28，28)的模型的屈曲应力降低，而具有(10，10)的模型保持不变。通过分析原子应力和原子弹性刚度系数的分布，发现在(17，17)和(28，28)模型中，由于C60的偏置，碳纳米管周向应力分布变得不均匀。这种应力不均匀降低了单壁碳纳米管和5WCNTs的屈曲强度。我们还研究了以(10，10)为最内层的单壁碳纳米管到5个碳纳米管，并等间隔地与多个C60 S进行了研究。未加C60的SWCNT和2WCNT发生了循环壳体屈曲。当C60 S之间的间隔不同于壳体循环屈曲的波长时，由于屈曲模式向局部屈曲转变，屈曲应力增大。在三层或更少层的模型中，局部屈曲发生在C60的斜面附近，在那里碳纳米管与C60之间有吸引力的相互作用重叠。在4WCNTs和5WCNTs中，C60的存在不影响其屈曲行为。对于中空无周向偏置材料的豆荚结构，如包裹C60 S的四壁或多壁碳纳米管，包裹的材料很可能不影响多壁碳纳米管的屈曲行为。
Carbon nanotubes (CNTs) have a hollow structure and high aspect ratio. Generally, buckling under axial compression is dependent on the dimensions and chirality of the CNT and materials encapsulated in the hollow space. In this study, we performed compressive molecular dynamics simulations of (10, 10),(17, 17), and (28, 28) single-walled CNTs (SWCNTs) and counterpart five-walled CNTS (5WCNTs) with each of these SWCNT as the innermost layer, with and without an encapsulated C 60. We found that the buckling stress decreased as the CNT diameter increased. After inserting a C 60, the buckling stress decreased for models with (17, 17) and (28, 28) but remained unchanged for models with (10, 10). By analyzing the distributions of atomic stress and atomic elastic stiffness coefficient, we found that the stress distribution became non-uniform in the circumferential direction of CNTs due to the bias of C 60 in models with (17, 17) and (28, 28). This stress heterogeneity decreased the buckling strength in both SWCNTs and 5WCNTs. We also investigated SWCNTs to 5WCNTs with (10, 10) as the innermost layer and with multiple C 60 s at equal intervals. Cyclic shell buckling occurred in SWCNT and 2WCNT without C 60. When the interval between C 60 s differed from the wavelength of cyclic shell buckling, the buckling stress increased due to a change in the buckling mode to local buckling. In models with three or less layers, local buckling occurred in the oblique vicinity of C 60, where attractive interactions between CNTs and C 60 s overlapped. In 4WCNTs and 5WCNTs, the presence of C 60 did not affect the buckling behavior. In the case of a peapod structure with no circumferential bias for materials in the hollow space, such as four-or more walled CNTs with encapsulated C 60 s, it is likely that the encapsulated material does not affect the buckling behavior of multi-walled CNTs.