Achieving superior wear resistance in epoxy resin with novel graphitic carbon nitride/ polysulfone microcapsules

Abstract

Microcapsules that release lubricating oil within polymer materials can impart excellent tribological properties. However, conventional microcapsules still face challenges related to insufficient wear resistance. In this study, polysulfone microcapsules encapsulating Polyalphaolefin 10 (PAO 10) lubricating oil (MCPs) were synthesized via the solvent evaporation method. The MCPs were then modified by grafting graphitic carbon nitride (g-C₃N₄), yielding microcapsules with an oil content of 54.5 % and an average particle size of 1.6 ± 0.9 μm. The obtained microcapsules were embedded into an epoxy resin matrix to prepare high-performance self-lubricating composite materials demonstrating their excellent tribological properties. The optimal microcapsule content was determined to be 25 wt% through friction experiments. The timely release of lubricating oil, the high load-bearing capacity of g-C₃N₄, and the solid-liquid synergy between these components significantly enhanced the tribological performance of the composite. Compared with pure epoxy resin, the friction coefficient was reduced by 86.1 % (from 0.656 to 0.089), and the wear rate was reduced by 98.8 % (from 9.22 ×10⁻⁵ mm³/N·m to 0.168 ×10⁻⁵ mm³/N·m). Moreover, the modified microcapsules not only enhance the tribological properties but also improve the mechanical properties of the composite. The addition of g-C₃N₄ increased the tensile strength of the material by 7.7 %. Finally, the friction mechanism of microcapsules in the composite was thoroughly investigated. Overall, this study offers innovative insights into designing advanced microcapsules and developing low-friction, wear-resistant, self-lubricating composites.