Study On Friction And Wear Properties Of Polyimide Composites Reinforced With Nano-Hybrid Materials

Polymide(PI)is a significant aromatic polymer material with important application value due to its high specific strength,radiation resistance,excellent thermal stability and mechanical properties.Therefore,PI used widely in 5G communication technologies,aerospace,rail transportation,microelectronics and tribology fields widely.Nevertheless,the higher requirements are put forward for the comprehensive properties of polymer materials,including tribological properties with the increasingly demanding service conditions of polymer materials.So it is time to find a suitable method to improve the performance of pure polyimide become a research hot spot.In this paper,two kinds of nano-hybrid composites were prepared and introduced into the polyimide matrix for improving the friction and wear properties of polyimides and improve the performance defects of polyimides effectively.The experimental results showed that the introduction of nanometer hybrid materials was an effective way to modify polyimides,so as to broaden the engineering application range of polyimides.The main contents and results of this paper are following:1.Cu nanoparticles(CuNPs)are usually used as a kind of lubricant additices because its easy shear and exceellent bearing capacity;and the grahene(G)is a 2D material,the exceptional mechanical properties and easy to shear make it a typical lubricant additive.Therefore,it is a good idea to make a combination of CuNPs and rGO for improving tribological properties.In this experiment,a core-shell structure of Cu@rGO contained CuNPs and rGO prepared by electrostatic self-assembly method.Then,the core-shell Cu@rGO was added into the PI matrix and the PI composites was prepared by hot pressing technlogy to explore the tribological properties of it.The research results showed that the Cu@rGO composite had a positive effect to the tribological properties of pure PI.Besides,compared with the PI composites added with Cu,rGO or their mixture(Cu/rGO),the hybrid of Cu@rGO reinforced PI composites expressed better tribological properties.This was mainly attributed to the fact that the CuNPs with great load-bearing property can improve the wear resistance of PI composites effectively.On the other hand,the excellent self-lubricating performance of rGO reduced the friction force between the PI composites and the counterpart ball surface,leading to the better friction performance.2.Molybdenum disulfide(MoS₂)is an important lubricating additive with self-lubricating properties,which is widely used in the tribology field.Moreover,as a kind of metal compound,zinc sulfide(ZnS)particles have been applied to a certain extent because of its self-lubricating property.In this experiment,the hybrid of MoS₂/ZnS as the reinforcing phase of PI was synthesized by hydrothermal method in one step,and the PI/MoS₂/ZnS composites were obtained by hot press molding process.The correlative thermal tests results of TGA and DSC showed that the introduction of MoS₂/ZnS improved the thermal stability of PI.The results of friction tests showed that the PI/MoS₂/ZnS composites exhibited better tribological properties than PI/MoS₂ or PI/ZnS composites,which was ascribed to the synergistic enhancement effect between MoS₂ nano-sheets and ZnS nanoparticles.