The disentanglement and shear properties of amorphous polyethylene during friction: Insights from molecular dynamics simulations

• Published in: Applied surface science 2022-04, Vol.580, p.152301, Article 152301
• Main Authors: Zheng, Ting, Wang, Shukai, Zhou, Lin, Li, Xin, Zhang, Huichen
• Format: Article
• Language: English
• Subjects: Amorphous polyethylene; Crystallinity; Disentanglement; Friction; MD simulations
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2021.152301

[Display omitted] •The disentanglement and crystallinity of amorphous PE increase during friction.•Restricted molecular mobility of PE chains hinders the disentanglement in friction.•The rise in normal load and velocity cause reduced crystallinity of PE substrate.•The distribution and migration of adsorbed PE chains exhibit directional features.•Transfer films reduce the friction resistance and weaken the crystallization of PE. This work is designed to provide new insights into the friction process on the amorphous polyethylene substrate by means of classical molecular dynamics (MD) simulations. Both the rises in normal pressures and sliding velocities could result in an increase in the internal shear force. The disentanglement and the crystallinity of the amorphous PE substrate increased during friction, which were strengthened at smaller normal pressures and smaller sliding velocities. The distribution and migration of the adsorbed polyethylene chains during the friction process exhibit directional features along the 〈110〉 direction as restricted by the surface Cu atoms. Furthermore, the existence of a thin transfer film adsorbing on the Cu slab, helps to reduce the shear forces by 27.8%∼31.9% and hinders the increase of crystallinity during friction. In addition, a frequent renewal of the PE substrate surface was observed at the interface and an apparent separation of the transfer film from the PE substrate occurs with the extension of the friction process.