Preparation of graphene oxide/epoxy nanocomposites with significantly improved mechanical properties

(2014) Preparation of graphene oxide/epoxy nanocomposites with significantly improved mechanical properties. Notice: Changes introduced as a result of publishing processes such as copy-editing and formatting may not be reflected in this document. For a definitive version of this work, please refer to the published source: The effect of graphene oxide (GO) on the mechanical properties and the curing reaction of Diglycidyl Ether of Bisphenol A/F and Triethylenetetramine epoxy system was investigated. GO was prepared by oxidation of graphite flakes and characterized by spectroscopic and microscopic techniques. Epoxy nanocomposites were fabricated with different GO loading by solution mixing technique. It was found that incorporation of small amount of GO into the epoxy matrix significantly enhanced the mechanical properties of the epoxy. In particular, model I fracture toughness was increased by nearly 50% with the addition of 0.1 wt% GO to epoxy. The toughening mechanism was understood by fractography analysis of the tested samples. The more irregular, coarse and multi-plane fracture surfaces of the epoxy/GO nanocomposites were observed. This implies that the two-dimensional GO sheets effectively disturbed and deflected the crack propagation. At 0.5 wt% GO, elastic modulus was ~35% greater than neat epoxy. Differential scanning calorimetry results showed that GO addition moderately affect the glass transition temperature (T g) of epoxy. The maximum decrease of T g by ~7 o C was shown for the nanocomposite with 0.5 wt% GO. DSC results further revealed that GO significantly hindered the cure reaction in the epoxy system.