Preparation of Novel Nanocomposites Modified with Hybrid Nano-Reinforcements

In this study, graphene nanoplatelets (GNP) and cup-stacked carbon nanotubes (CSCNT) were used to enhance the mechanical properties of carbon fibre epoxy composites. The principal challenge was to accomplish homogenous... [ view full abstract ]

In this study, graphene nanoplatelets (GNP) and cup-stacked carbon nanotubes (CSCNT) were used to enhance the mechanical properties of carbon fibre epoxy composites. The principal challenge was to accomplish homogenous dispersion and full exfoliation of the nanoparticles in the matrix. The combined techniques of sonication and ball milling were used to disperse the two types of nano-reinforcements into the epoxy matrix at various weight concentrations, ranging from 0 to 7wt.%. Characterisation of the nanocomposites was performed via mechanical testing on three types of epoxy nanocomposites: a) GNP/epoxy, b) CSCNT/epoxy, c) hybrid GNP -CSCNT/epoxy. The results showed that optimum mechanical strength was achieved after adding 5wt. % of GNP, 6wt. % of CSCNT and 4wt. % of hybrid nanofillers to the epoxy matrix; thus, the weight ratio of the hybrid nanofillers was equalised. The optimum weight concentration for each type of nanocomposites was subsequently used to improve the mechanical properties of carbon fibre reinforced composites. Three types of woven roving carbon fibre composite laminates using the abovementioned nanofilled epoxy formulations were produced via the impregnation route using the hand lay-up method with the following formulations: a) GNP /CF/epoxy, b) CSCNT/CF/epoxy, and c) hybrid GNP-CSCNT/CF/ epoxy. Flexural strength and interlaminar fracture toughness (mode I) tests were conducted on the laminates produced. The results revealed that the flexural strength and propagation energy toughness increased by approximately 20% and 15% in the GNP/CF/ epoxy respectively, and 25% and 104% in the CSCNT/CF/epoxy respectively (see Fig 1 & Table 1). In addition, there was a significant improvement of approximately 18% and 73% respectively in the hybrid GNP-CSCNT/CF/epoxy composite laminates. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEMs) were used to evaluate the dispersion of the nano-reinforcements into the epoxy matrix and the fracture mechanism of the epoxy composites (see Fig 2). The microstructural details demonstrated a uniform dispersion and optimum exfoliation of the nanoparticles, and strong bond between the nanofilled epoxy matrix and the carbon fibre reinforcement network