Mechanical behavior and micro-mechanism of carbon nanotube networks under friction

TX Hu and GA Qian and XQ Wu and C Wang, CARBON, 200, 108-115 (2022).

DOI: 10.1016/j.carbon.2022.08.042

Friction behavior of carbon nanotube networks (CNNs) is ubiquitous in applications, however, is poorly inves-tigated. Here, we employ coarse- grained molecular dynamics (CGMD) simulations to investigate friction be-haviors and microscopic mechanism of CNNs. We first give a phase diagram to determine the initial contacting state of "supported" or "trapped" for an indenter in CNNs. In a "supported" state, friction force is mainly orig-inated from the local surface adhesion of CNNs which experience stable elastic deformation in friction process. In contrast, in a "trapped" state, friction force is mainly activated by nonlocal reconstitution of carbon nanotubes (CNTs) accompanied with irreversible bond breaking. Furthermore, with an increased normal pressure, the friction force keeps nearly constant for a "supported" indenter while it increases linearly for a "trapped" one; the friction force is linearly or nonlinearly related to the sliding velocity of an indenter in a supported or trapped state. Importantly, there is a critical crosslink density, above which, the coefficient of friction is greatly decreased due to enhanced integrity of CNNs. These results provide a profound understanding of friction deformation behavior of CNNs, which is of great significance for optimal design in practical applications.

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