Polyimide/mesoporous silica nanocomposites: Characterization of mechanical and thermal properties and tribochemistry in dry sliding condition

Abstract

Mesoporous silica (MPS) with tunable mesopore channels can be used to reinforce polymers and has great potential in tribological applications, which is rarely investigated by research community. In this study, comprehensive properties of polyimide (PI)/MPS composites were investigated. Specially, the tribochemistry of PI/MPS composites in dry sliding against bearing steel was explicitly studied by the combined use of X-ray photoelectron spectroscopy (XPS) and Raman analysis. The results demonstrated a slightly decreased tensile strength but increased modulus, microhardness and thermal stability of the PI/MPS composites. The incorporation of 1.5 wt.% MPS increased the anti-wear resistance of PI by more than 14-fold. This was highly associated with the formation of high-quality transfer film on the bearing steel counterpart surface. Relevant tribochemistry was thoroughly revealed by XPS analysis on the transfer film and Raman analysis on the worn surfaces. This study confirmed the high efficiency of using MPS to reinforce PI polymer for tribological applications and elaborated tribochemistry to further better understand tribochemical reactions in polymer-metal rubbing systems.

Transfer film formation mechanism and tribochemistry evolution of a low-wear polyimide/mesoporous silica nanocomposite in dry sliding against bearing steel

“…Chang et al [30] correlated layer thickness of transfer films with tribological properties of polymer composites as a function of transfer film efficiency factor so that the friction and wear of the sliding system could be analyzed, resulting in a Stribeck type diagram. Nevertheless, while improved transfer film quality has been explained as one major reason for the enhancement of triobological properties of PI-matrix composites [1,2,[6][7][8][9][10], the transfer film formation mechanism of PI-matrix composites still remains neglected. In most cases, transfer films are regarded as a consequence of tribological behavior and studies considering the formation and evolution of the transfer film as a process of tribological behavior are rarely found.…”

“…In most cases, transfer films are regarded as a consequence of tribological behavior and studies considering the formation and evolution of the transfer film as a process of tribological behavior are rarely found. Our previous work [1,31] demonstrated excellent wear resistance of PI/MPS nanocomposites and the reinforcing mechanism arose from improved-quality transfer films induced by tribochemical reactions between mesoporous silica (MPS) and PI molecules. However, formation mechanism of such critical transfer film as well as accompanying tribochemistry evolution remain mysterious.…”

“…In a dry sliding process against a metal, large PI wear debris or plates are easily sheared off because the rigidity of main chains and some are transferred on surfaces of metal counterpart, causing high friction and wear of pure PI. Such triobofilms are generally thick, lumpy and weakly bonded with metal pieces [1,6]. The incorporation of different micro/nanofillers such as carbon fibers, glass fibers, aramid fibers, ceramics and solid lubricants has been reported to contribute to over 50% increase in the wear resistance of PI [7][8][9].…”

Effects of silica nanoparticles on tribology performance of poly(Epoxy Resin‐Bismaleimide)‐based nanocomposites

“…The friction coefficients of OSNPs‐filled composites were lower than those of unfilled EP‐BMI‐DDM copolymer and decreased with increasing OSNPs content. The lowest friction coefficient value (0.17) was observed at the OSNPs content of 2 wt%, and this result was partially due to the high number of OSNPs on the worn surface offering a larger contact area between the particles and wear pin, resulting in better wear resistance .…”

Improved tribological properties of polyimide composites by micro–nano reinforcement

“…Polymer and polymer composites were widely used as a mechanical and tribo‐materials due to its excellent properties, such as high strength, light weight, excellent thermal stability, as well as anti‐wear and solvent resistance . Polymer composites with desired physical and chemical properties could be reinforced with different fibers, filled with organic fillers and inorganic fillers to meet the different requirements . The common method and the best way to improve its strength was to add various kinds of fibers into the polymer matrix …”