Impacts of polyimide enhanced by amino-modified fluorinated graphene: Thermal, mechanical and tribological behaviors

The fluorinated graphene (FG) is modified to get the amino-FG (AFG) which is applied as nanofiller of the polyimide (PI). The repulsion between the C-F bonds endows the AFG with well dispersion in polyimide (PI) matrix, and the amino groups of the AFG react with pyromellitic dianhydride to form strong physical and chemical interactions between the AFG and the PI chains. The results exhibit that the AFG obviously enhances the thermal stability, mechanical performances and wear resistant properties of the PI. When the AFG content reaches 0.5 wt%, the PI/AFG-0.5 composite shows the 35.5% higher tensile stress and 50% higher wear resistance than the PI, which are also higher than the PI/FG-0.5. The strong physical and chemical interactions between the AFG and the PI matrix enhance the interfacial compatibility of the PI/AFG composite, which is better to transfer the stress and heat, so as to enhance the mechanical and tribological properties of the PI. The worn surface changes of the PI/AFG composites indicate that the tribological mechanisms are the synergistic reaction of the abrasive wear and the fatigue wear.