非晶态聚合物摩擦行为的分子动力学模拟

Molecular Dynamics Simulations of Amorphous Polymer Friction Behavior

为了探究锥形光滑探头在非晶态聚合物表面上滑动时聚合物所表现的摩擦行为,在不同温度、不同粘着强度下,采用珠簧模型,应用分子动力学方法模拟了此滑动过程。通过分析此滑动过程中的聚合物链结构(键取向和链构象),阐释了聚合物薄膜与探头间交接区的结构动力学特征。当聚合物处于玻璃态,且探头与基体之间的作用是粘着作用时,其交接区中的高分子链的键取向沿滑动方向取向。且表征链构象的回转半径值也在滑动方向上增大到滑动前的10倍左右,即链构象发生了显著的改变。

With various temperatures and adhesion strength considered,a scratch test between a conical probe and amorphous polymer film modeled by coarse-grained model(CG)was simulated by molecular dynamics(MD)for exploring the friction behavior of the amorphous polymer.After the polymer chain structure(bond orientation and chain configuration)was studied,the structural dynamics of the polymer at the interface between the tip and the polymer film was explained.If the polymer was in a glassy state for a strongly attractive tip,the bond orientation of polymer chains in the interface oriented in the sliding direction.The gyration tensor,characterization of the chain configuration,increased to about 10 times in the sliding direction compared with that of before sliding.That is,the chain conformation was changed significantly.