Effect of Dispersion Morphology of Graphene in Polyoxymethylene/Polyurethane Multiphase System on Wear Resistance Properties

ABSTRACT Polyoxymethylene (POM) features inherent self‐lubrication, excellent chemical resistance, and low cost, making it a common matrix for wear‐resistant polymer composites. In the modification research of POM, the thermoplastic polyurethane elastomer (TPU) toughening of POM has been industrialized, yet it only slightly improves wear resistance. Therefore, in this study, solid‐state shear milling technology (S 3 M) was used to modify the multi‐phase system of POM/TPU with graphene, changing the dispersion degree of graphene in both phases to make a significant enhancement of wear‐resistant properties of the composites. The mechanism of its wear‐resistant properties was investigated. The results showed that, after graphene was decarboxylated via silane coupling agent KH‐570, S 3 M drives graphene to migrate from the TPU dispersed phase into the POM continuous matrix. The spherical POM/TPU hybrid microstructures are consequently formed on friction interfaces, acting as microscale ball bearings converting sliding friction into rolling friction. This structural evolution significantly lowers the friction coefficient and specific wear rate of composites. Additionally, due to the decarboxylation of graphene, the thermal properties of the multiphase composites relatively increase. The friction coefficient is reduced from 0.32 to 0.15, and the specific wear rate is reduced from 6.28 × 10 −6 mm 3 /(N·m) to 5.5 × 10 −6 mm 3 /(N·m), which greatly improves the wear performance.