Effect of Graphene Nanosheets on the Oil-bearing Properties and Tribological Properties of Porous PI Composites

Porous polyimide (PI) is widely used, but its friction and wear characteristics need to be further improved. Graphene nanosheets (GNS) were used as modifiers to prepare porous PI composites. The impact of GNS fillers on the impact performance, oil content and tribological properties of porous PI materials were studied, and the coordinated lubrication mechanism of GNS, PI and lubrications were explored. The results show that adding a certain amount of GNS can increase the oil content and oil retention rate of porous PI materials. After adding the GNS filler, the pore size and porosity of the composite material are increased, which makes the composite material have a stronger adsorption force for oil and improves its oil storage capacity. The impact strength of the composite material increases first and then decreases with the change of GNS content. A small amount of GNS is dispersed in the matrix, which can achieve toughening results, while a large amount of GNS weakens the bonding between PI particles. GNS is easy to agglomerate leads to poor interface bonding. When 0. 5% GNS is added, the porous PI composite exhibits the best tribological performance. Compared with pure PI, the friction factor is reduced by 37. 2%, and the wear scar width is reduced by 26. 5%. A proper amount of GNS can further improve the oil-containing properties and friction properties of the material.