Effect of CNTs addition on the fracture behaviour of neat epoxy and epoxy-carbon fiber reinforced composites

Considerably improved fracture resistance can be introduced to monolithic materials or even to the composites by introducing carbon fibers and carbon nanotubes (CNTs) as hybrid reinforcements. The present study describes the influence of amino functionalized multi walled CNTs (AMWCNTs) addition on the fracture behaviour of carbon fiber reinforced hybrid composite and neat epoxy matrix. AMWCNTs are introduced in thermosetting epoxy resin and then carbon fibers are reinforced in the matrix. A fixed quantity (0.5 weight %) of AMWCNTs are dispersed in the epoxy matrix. Amino functionalized MWCNTs were used for homogenous dispersion and synthesized by probe type sonicator. Fractograhic studies were carried out to know the distribution of AMWCNTs in epoxy matrix. The introduction of AMWCNTs in epoxy matrix significantly increases the overall fracture energy. It is speculated that AMWCNTs due to their large aspect ratio have a significant toughening effect since extra energy is needed in order to pull them out from the polymer epoxy matrix and start the crack propagation following a kinking out pattern at nanoscale.