Cryogenic mechanical properties and liquid oxygen compatibility of MXene/epoxy nanocomposites

Due to their great potential in saving weight, carbon fiber–reinforced epoxy composites are receiving great interests for the liquid oxygen (LOX) cryotank as the largest component in the spacecraft propulsion system. However, the application of epoxy resins as matrices in LOX composite cryotanks is severely constrained by their LOX incompatibility and poor cryogenic mechanical properties. To address these issues, two-dimensional MXene nanosheets as multifunctional fillers are introduced into an epoxy resin, and the effects of MXene on the cryogenic mechanical properties and liquid oxygen compatibility of the epoxy resin are comprehensively examined. It is interestingly observed that the mechanical properties at both room temperature (RT) and cryogenic temperature (90 K) of the epoxy resin, including tensile strength, elastic modulus, and fracture toughness, are significantly enhanced with the addition of low content MXene; and the MXene/epoxy nanocomposite with 0.10 wt.% MXene exhibits the optimal mechanical performances. MXene is also effective in enhancing the LOX compatibility of the epoxy, and the MXene/epoxy nanocomposite with 0.20 wt.% MXene completely passes the LOX impact test. In overall, the MXene/epoxy nanocomposite with simultaneously enhanced cryogenic mechanical properties and LOX compatibility is promising for applications in LOX composite tanks.