Tribological properties of polydopamine modified microcapsules/polyimide based composites

Polyimide (PI) is a widely used self-lubricating composite material in tribological applications, such as gears and bearings. However, unfilled PI suffers from a high coefficient of friction(COF) and an increased wear rate, which limits its performance in demanding environments. In this study, the development of self-lubricating PI composites was employed by incorporating polydopamine (PDA) modified microcapsules into the PI matrix, with a focus on their tribological behavior. Microcapsules were prepared via solvent evaporation, with polysulfone (PSF) as the wall material. PDA modification of the microcapsules surface was exhibited to enhance thermal stability. The tribological performance of the resulting PI composites was systematically evaluated under varying conditions, including microcapsule contents, load and temperature, using ball-on-disk reciprocating friction test. The results was shown that the PI-based composites with PDA-modified microcapsules was presented the lowest friction and wear rate. The optimal tribological performance was achieved with 12 wt% microcapsules at the load of 30 N. The improved performance was attributed to forming of a lubricating transfer film, facilitated by the controlled release of base oil from the microcapsules during the friction process. Therefore, the developed self-lubricating materials exhibit significant potential for advanced engineering applications, notably where reduced friction and wear resistance are critical.