不同温度下环氧/聚氨酯共聚物摩擦学性能的分子动力学模拟研究  

Molecular Dynamics Simulations on the Tribological Properties of the Tunable Block Copolymers of Epoxy/Polyurethane in Different Temperatures

作　　者：齐慧敏 崔怡泼 余家欣[1] 赵盖[2] 张亚锋[1] 雷雪梅 张德虎[1] QI Huimin;CUI Yipo;YU Jiaxin;ZHAO Gai;ZHANG Yafeng;LEI Xuemei;ZHANG Dehu(Key Laboratory of Manufacturing Process Testing Technology,Ministry of Education,Southwest University of Science and Technology,Sichuan Mianyang 621010,China;State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics,Jiangsu Nanjing 210016,China;State Key Laboratory of Solid Lubrication,Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences,Gansu Lanzhou 730000,China)

机构地区：[1]西南科技大学制造过程与测试技术教育部重点实验室,四川绵阳621010 [2]南京航空航天大学机械结构力学与控制国家重点实验室,江苏南京210016 [3]中国科学院兰州化学物理研究所固体润滑国家重点实验室,甘肃兰州730000

出　　处：《摩擦学学报》2023年第9期1016-1025,共10页Tribology

基　　金：国家自然科学基金(52105214,52075247);中国科学院兰州化学物理研究所固体润滑国家重点实验室开放课题(LSL-1902);四川省自然科学基金青年基金(2022NSFSC1928)资助。

摘　　要：为探究不同温度下共聚物的摩擦学性能,设计了分子比例为2:1和1:2的环氧/聚氨酯共聚物体系(2EP/PU和2PU/EP).通过分子动力学(MD)模拟,考察了共聚物在不同温度下的力学性能,结果表明在223、298和373 K时,2PU/EP的杨氏模量分别比2EP/PU提高了8.8%、7.1%和1.7%,主要归因于聚氨酯的线性结构增加了分子链的堆积密度,使得共聚物的密度增加,从而模量和强度相对较大.同时,建立共聚物与铁层的滑动摩擦模型,基于原子水平分析了材料的摩擦剪切性能.2EP/PU在223 K时的摩擦系数最低为0.067,比298和373 K时降低了近40%,而2PU/EP的摩擦系数在373 K时最低为0.105,在223和298 K时分别提高至0.112和0.115,且2PU/EP的摩擦系数高于2EP/PU,这与不同温度下聚氨酯的分子极性、共聚合物和铁层之间的相互作用以及范德华力等密切相关.In order to investigate the tribological properties of copolymer at different temperatures,epoxy/polyurethane copolymer systems(2EP/PU and 2PU/EP)with molecular ratios of 2:1 and 1:2 were designed.Molecular dynamics(MD)simulations were conducted to simulate the physical performance and interfacial shear behavior of the sliding system.Firstly,the density,electrostatic interaction and van der Waals force of copolymers 2EP/PU and 2PU/EP at different temperatures before and after optimization were compared and analyzed.Moreover,the mechanical properties at 223 K,298 K and 373 K were investigated.The results showed that the Young's modulus of 2PU/EP increased by 8.8%,7.1%and 1.7%at 223 K,298 K and 373 K,respectively,compared with that of 2EP/PU.It was mainly attributed to the linear structure of polyurethane,which increased the bulk density of molecular chains and stabilized the state of copolymer.At the same time,the sliding friction model between copolymer and iron layer was established,and the friction and wear properties of the materials were analyzed at atomic level.The lowest friction coefficient of 2EP/PU at 223 K was 0.067,which was nearly 40%lower than that at 298 K and 373 K.The friction coefficient of 2PU/EP was 0.105 at 373 K,and increased to 0.112 and 0.115 at 223 and 298 K,respectively.It was speculated that at 373 K,the electrostatic(Coulomb)interaction and van der Waals interaction between 2PU/EP molecules increased,which weakened the interaction between the Fe layer and the copolymer layer.In addition,the friction coefficient of 2PU/EP was higher than 2EP/PU,because the strong polarity of PU enhanced the interaction between the sliding interfaces and impeded the frictional shear process.Comparing the total energy of 2EP/PU and 2PU/EP sliding systems,it was found that total energy of both copolymers was almost the same.Nevertheless,the temperature had a great influence on the molecular interaction energy.At 373 K,the total energy of 2EP/PU and 2PU/EP was about 4250 kcal/mol.Decreasing the temperature,t

关 键 词：分子动力学模拟 环氧/聚氨酯共聚物 摩擦剪切 摩擦系数 界面能量 

分 类 号：TH117.1[机械工程—机械设计及理论]