Mechanical and friction and wear properties of aramid fibrid-polydopamine/polyimide-phenolic resin composite films

The aramid fibrid-polydopamine/polyimide-phenolic resin (AF-PDA/PI-PF) composite films with 15wt% AF and 7.5wt% PDA were prepared by wet forming and hot-pressing curing technique using PDA modified PI fiber and PF as the matrix with the introduction of AF as reinforcement. The effects of the addition of AF and PDA modification on the mechanical properties and friction and wear properties of PI-PF composite films and wear mechanism were mainly studied. The results show that when adding AF and using PDA modified PI fiber simultaneously, the stress, the tensile index and the interlayer bonding strength of AF-PDA/PI-PF composite films are 47.54 MPa, 56.91 Nmg^-1 and 1 265.6 Jm^-2, respectively, which increase by 33.65%, 41.67% and 64.11% compared with PI-PF composite films. The wear rate of AF-PDA/PI-PF composite films is 1.01×10^-4 mm³ J^-1, which is 34.84% lower than PI-PF composite films. The main wear mechanism of AF-PDA/PI-PF composite films is proposed to be adhesive wear. The PI fiber and AF can form "interpenetrating networks" structure, and the PDA modification of PI fiber improves the surface activity of PI fiber, which plays a synergistic role in improving the interfacial bonding strength between PI fiber and PF, as well as the mechanical properties and friction and wear properties of AF-PDA/PI-PF composite films.