Mode II Interfacial Fracture Toughness of Multi-Walled Carbon Nanotubes Reinforced Nanocomposite Film on Aluminum Substrate

In this investigation, various loadings of multi-walled carbon nanotubes (MWCNTs) ranging from 0.3–1.0 wt % were incorporated into the epoxy to fabricate the nanocomposites. Nanocomposite film with a thickness of 0.2 mm was deposited on an aluminum substrate through a hot-pressing process. Theoretical expression of the model II strain energy release rate for the film/substrate composite structure was derived. End-notched flexure (ENF) tests were performed to characterize the mode II fracture energy of the composite structure. Experimental results indicate that the elastic modulus, ultimate strength, and mode II fracture energy increase as the MWCNT loading in the nanocomposite increases. In the case of nanocomposite film with 1.0 wt % of MWCNTs, the elastic modulus, ultimate strength, and mode II interfacial fracture toughness are increased by 20.6%, 21.1%, and 54.4%, respectively in comparison with neat epoxy. In addition, the dispersion of MWCNTs in the epoxy-based matrix was investigated using scanning electron microscope (SEM). The SEM images depict that MWCNTs are well dispersed leading to the enhancement of the mechanical properties of the nanocomposite.