碳纳米管及石墨烯协同增强尼龙6摩擦学性能的分子动力学模拟

Molecular Dynamics Simulation of the Tribological Properties of Nylon 6 Synergistically Reinforced by Carbon Nanotubes and Graphene

为研究碳纳米管(CNT)和石墨烯片(GNS)协同增强尼龙6(PA6)复合材料摩擦学及力学性能的微观机制,利用分子动力学方法模拟PA6及其复合材料的拉伸过程及摩擦学行为,分析CNT、GNS对PA6复合材料力学及摩擦学性能的影响。建立Fe原子与纯PA6和PA6/CNT、PA6/GNS、PA6/GNS/CNT复合材料组成的摩擦学模型,并对模型进行几何优化、退火及动力学平衡,通过对Fe原子施加0.2 GPa应力及0.01 nm/ps速度进行摩擦模拟。研究结果发现,PA6/GNS/CNT复合材料摩擦因数在所有材料中最低为0.252;相比其他3种材料,PA6/GNS/CNT复合材料的抗剪切性能最好,且弹性模量及剪切模量均有提高。通过对比分析4种材料的径向分布函数、摩擦界面温度、材料总势能揭示了CNT和GNS协同增强PA6摩擦学及力学性能的作用机制,指出加入的CNT/GNS通过范德华及静电力作用降低了PA6与Fe原子摩擦副之间的相互作用,此外一维CNT与二维GNS通过π-π堆叠杂化作用形成了3D杂交堆叠体系,协同增强了PA6的摩擦学性能。

In order to study the micro mechanism of synergistic enhancement of the tribological and mechanical properties of nylon 6(PA6)composites by carbon nanotube(CNT)and graphene nanosheets(GNS),the tensile process and tribological behavior of PA6 and its composites were simulated by molecular dynamics,and the effects of CNT and GNS on the mechanical and tribological properties of PA6 composites were analyzed.Tribological models consisting of Fe atoms and pure PA6 and PA6/CNT,PA6/GNS,PA6/GNS/CNT composites were established,and the models were geometrically optimized,annealed and dynamically balanced.Friction simulation was carried out by applying 0.2 GPa stress and 0.01 nm/ps velocity to Fe atoms.The results show that the friction coefficient of PA6/GNS/CNT composite is 0.252,which is the lowest among all materials.Compared to the other three materials,PA6/GNS/CNT composite material has the best shear resistance,and both the elastic modulus and shear modulus are improved.By comparing and analyzing the radial distribution function,friction interface temperature and total potential energy of the four materials,the synergistic reinforcement mechanism of CNT and GNS on the tribological and mechanical properties of PA6 composites was revealed.It is pointed out that the addition of CNT/GNS reduces the interaction between PA6 and Fe atomic friction pairs through van der Waals and electrostatic forces,and one-dimensional CNT and two-dimensional GNS form a 3D hybrid stacking system through π-π stacking hybridization,synergistically enhancing the tribological performance of PA6.