Mechanical and tribological performances of graphene reinforced polyimide composites

The graphene was prepared by reduction process of graphite oxide, and the polyimide (PI) composites reinforced by graphene were prepared by solution blending method. The mechanical and tribological properties of PI composites reinforced by graphene were evaluated, and the wear mechanism was also analyzed. The results show that the tensile strength, elongation at break and hardness of the composites increased and then decreased with the increasing content of graphene, while the impact strength increased and then decreased, and rose again. The polyimide composites filled with 1wt% graphene exhibited the ultimate value of the tensile strength and elongation at break, the two values had been increased by 149% and 652%, compared with the pure polyimide, respectively. The addition of graphene may effectively enhance the tribological properties of composites. Along with the graphene content increased, the wear rate of the composites declined and then rose, while the friction coefficient significantly reduce at first and then gently decrease. The wear rates of the composites display the gentle decline trend with an increase of load and ascendant trend with increasing sliding speed. The main wear mechanism of the composites modified by graphene was adhesive wear.