Page 205 - Carbon Nanotube Fibres and Yarns

Mechanics modeling of carbon nanotube yarns 195

Fig. 8.6 Friction enhancement for PVA-modified CNT contacts. (A) Simulation box
where a PVA molecule wraps around CNT-16. (B) (Top) The gray plots are the instan-
taneous pulling force acted on CNT-5 by fixing CNT-11, obtained every 2 ps. The black
ones are the averaged friction per 400 ps. (Bottom) As compared to the pulling force
acted on CNT-9 (gray curve), the friction force on CNT-5 (black curve) was much higher.
(C) PVA-induced structural deformation for CNT-16. (Reproduced with permission from X.
Zhang, Sliding friction at poly(vinyl alcohol)-modified carbon nanotube interfaces. Mater.
Res. Express 5 (1) (2018) 015007.)

8.4.1 Molecular dynamics
Prediction of the mechanical property of CNT yarns is a complicated process.
Sliding between CNTs is of fundamental importance in determining the yarn
mechanical behaviors, and the break of a CNT bundle could lead to a sudden
yarn failure. In reality, the non-alignment, loose packing, and entanglement
of CNTs, and the presence of soft polymers between the CNTs could cause
plastic deformation of CNT yarn under an external load. For example, a PVA-
infiltrated CNT yarn is usually stronger and tougher than its parent pure CNT