Effect of compression on the enhancement of friction and strengthen of double-walled carbon nanotube bundles: A molecular dynamics study

Interfacial friction plays a crucial role in the mechanical properties of carbon nanotube (CNT) based fibers, composites, and devices. With the molecular dynamics simulation, we investigate the compression effect on the friction within the 16 × (10, 10) @ (5, 5) double-walled CNTs. Our results show that the double-walled CNTs has perfect compression and recovery qualities, and its variation in sliding velocity also has good accordance with the single-walled CNTs. The structure transition varies during the three different deformation stages, which can be denoted by before the structure deformation, during the structure deformation, and after the structure deformation, of double-walled CNT under increasing pressure. And we find that, after deformation, the CNT collapse and the friction forces within the double-walled CNTs have at least 1.6 times larger than its beginning. Finally, in order to make comparisons with the same type double-walled CNT bundles, we constructed the 16 × (10, 10) @ (6, 6) bundles in theory and studied its sliding velocity, which shows that larger diameter inner CNTs have higher friction after deformation. This may provide an effective way to reinforce the strengthen of CNT fibers.