With the development of modern industry, the requirements for mechanical equipment are increasingly stringent, and increasing attention has been paid to reducing wear or lubrication in the movement of mechanical structural parts. Polymers are widely used in the field of mechanical structural parts due to their high processing performance and comprehensive performance. However, the relatively weak mechanical and tribological properties of polymers limit their further application in mechanical equipment lubrication. Incorporation of fillers is a common method to improve the friction properties of polymers. Among various fillers, carbon nanotubes (CNTs) are considered the ideal fillers to significantly improve the tribological properties of polymers. Therefore, this paper reviews the tribological properties of carbon nanotube modified polymer materials. The tribological wear mechanism of polymers and the influence of friction-reducing fillers on the tribological properties of polymers and the related lubrication mechanism explanation are outlined, and the factors influencing the tribological properties of composites by carbon nanotubes and the related lubrication mechanism explanation are analyzed. The presented review will be beneficial for the production of high-performance polymer nanocomposites.

A C₆₀-PEI-rGO hybrid was prepared by incorporating the fullerene (C₆₀) on the surface of PEI-modified reduced graphene oxide (rGO) and then used to modify the epoxy (EP) resin. Subsequently, the structure of GO and C₆₀-PEI-rGO hybrid were well characterized, showing that the C₆₀ was homogenously anchored on the surface of PEI-rGO. The flame retardancy, mechanical properties, and thermal stability of as-prepared C₆₀-PEI-rGO/EP nanocomposites were systematically investigated. Results show that the C₆₀-PEI-rGO hybrid exhibits high flame retarding efficiency for EP. Specifically, the time to ignition of epoxy increases from 68 to 89 s with the addition of 1.0 wt% C₆₀-PEI-rGO, which are unusual in polymer nanocomposites. In the meantime, the peaks of the heat release rate and total heat release of the modified epoxy reduce by 40.0% and 15.6%, respectively. The synergistic flame retardant mechanism of C₆₀-PEI-rGO to EP is attributed to its unique structure combining both the high efficiency in capturing free radicals by C₆₀, the barrier effect of layered of rGO and increase of crosslinking density of epoxy. It is shown that the thermal stability and mechanical properties of epoxy are simultaneously improved with the addition of C₆₀-PEI-rGO. This work may pioneer a new and efficient method to fabricate fire retardant thermosetting resins with simultaneously other improved properties.

To mitigate the interlayer defects and weak interfacial adhesion inherent in FFF-printed parts, thereby facilitating subsequent supercritical foaming applications, a microwave-assisted interlayer healing strategy is developed for FFF-printed, supercritical CO₂-foamed thermoplastic polyurethane (TPU) by incorporating aminated helical multi-walled carbon nanotubes (AS-MWCNTs). Owing to their unique helical morphology, AS-MWCNTs exhibit enhanced microwave absorption and localized heating capability, enabling selective thermal activation at interlayer regions within the foamed architecture. Microwave irradiation induces localized softening of the TPU matrix and promotes polymer chain mobility and interdiffusion across layer interfaces, while preserving the cellular morphology and bulk foamed structure. By optimizing AS-MWCNT loading, substantial improvements in interlayer bonding strength, energy absorption, and overall mechanical performance are achieved. This work provides an effective strategy to restore interlayer integrity in supercritical CO₂-foamed, additive manufactured elastomers and offers insights into the design of microwave-responsive, self-healing cellular materials.