Strengthening of Bisphenol-A Epoxy Resin by the Addition of Multi-Wall Carbon Nanotubes

Multi-wall carbon nanotubes (MWCNTs) were prepared by chemical vapour deposition and purified by thermal oxidation. The purified MWCNTs were functionalized by nitric acid and hydrogen peroxide processes, and subsequently, the MWCNTs were added in bisphenol-A epoxy to prepare 0.1% CNT- nanocomposites. Transmission electron microscopy, fourier transform infrared spectroscopy, rheological and mechanical testing showed that the MWCNTs functionalized by hydrogen peroxide processes were comprehensively de-roped causing their better dispersion and curing of the epoxy, which consequently resulted in higher mechanical properties of the nanocomposite. During fractography of the fractured specimens, a transition of the fracture behaviour was observed; smooth brittle fracture with fissure-like features having parallel planes perpendicular to crack propagation (in neat epoxy specimens) is transformed into mixed type fracture comprising variable angle steps like and fish scale like features (in functionalized CNT and epoxy specimens), which is indicative of the improvement in the fracture toughness.