Improving the tribological and mechanical properties of polyimide composites by incorporating functionalized graphene

To explore the effect of added graphene sheets (GNs) and added perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) on the tribological and mechanical performances of polyimide (PI) matrix, GNs and PTCDA reinforced PI-based composites were synthesized via the blending method. The tribological properties of GNs/PTCDA/PI (GAPI) composites with different weight ratios of GNs and PTCDA under dry sliding, deionized water lubrication, and kerosene lubrication were comparatively investigated. A synergism was found between GNs and PTCDA; this synergism endowed filled PI composites with a lower friction coefficient and showed an improved wear rate under different lubrication conditions, especially when the weight ratio of GNs and PTCDA was 1:1 (GAPI-1). Under dry sliding, deionized water lubrication, and kerosene lubrication, the friction coefficient of GAPI-1 composites decreased by 41.1%, 70%, and 35.7%, respectively, while the wear rate decreased by 39%, 50%, and 25.1%, respectively. Meanwhile, the tensile strength, tensile modulus, and the elongation at break of GAPI-1 films increased by 40.8%, 51.3%, and 49.2%, respectively, relative to those of pure PI. We anticipate that this work can be used to exploit a simple and effective method for preparing materials for bearings and transmission parts that possess good tribological properties under harsh lubrication conditions.