Liquid metal synthesis of two-dimensional aluminium oxide platelets to reinforce epoxy composites

A liquid metal synthesis process provides a new low energy pathway avenue to manufacture various low-dimensional nanomaterials in order to improve the mechanical properties of polymer composites. This paper presents an investigation of the strengthening and toughening performances of two-dimensional platelets of boehmite (γ-AlO(OH)) and alumina (γ-Al2O3). Using a liquid metal alloy reaction process, two-dimensional metal oxide hydroxide and oxide platelets were synthesised and then used for reinforcing epoxy polymer composites at different weight fractions up to 10%. Both boehmite and alumina platelets increased the tensile modulus, yield stress and fracture toughness of the epoxy composite by up to 40%, 35% and 320%, respectively. Of the two materials, the boehmite platelets were more effective than the alumina platelets in increasing the tensile modulus (up to 27%) and ultimate strength (up to 14%) of the epoxy. In contrast, the alumina platelets promoted a 50% greater improvement to the mode I fracture energy when compared to using boehmite platelets. The primary mechanisms responsible for the measured property improvements are identified.