不同构型聚α-烯烃分子润滑性的分子动力学模拟

采用分子动力学方法研究不同构型的直链和支链化润滑油聚α-烯烃(PAO)在剪切铁板间的黏度、 摩擦性以及油膜内PAO分子的聚集行为, 从微观角度解释了PAO分子结构与润滑油膜稳定性的关系. 模拟结果表明, 相比于直链PAO, 支链化PAO润滑油剪切黏度受剪切速率影响较小; 支链化PAO剪切摩擦系数小于直链PAO润滑油; 对比直链PAO分子, 支链化PAO分子由于侧链的存在, 可在润滑体系内多层吸附层间形成复杂的网状结构, 降低PAO分子在剪切力作用下的移动. 这种网状结构有利于润滑油膜的稳定, 延长了润滑油的使用寿命.

Molecular Dynamics Simulation of Different Configurations of PAO Molecules in Shear Iron Plates†

The viscosity, friction and distribution of linear and branched polyalphaolefin(PAO) lubricants molecules on sheared iron plates were investigated with molecular dynamics simulation at the molecular level. The simulation results show that compared to the linear PAO lubricants, the shear viscosity of branched PAO lubricants are less affected by the shear rate; the friction coefficient of branched PAO lubricants is less than that of linear PAO lubricant; due to the presence of side chains, the branched PAO molecules are difficult to spread on the surface of iron, resulting into the complex network structure between different adsorbed layers of lubricants and reducing the mobility of branched PAO molecules under the additional shear force. The network structure of lubricants on the surface represents one stable lubricant film, and prolongs the life of lubricants.