Influence of the modification with MWCNT on the interlaminar fracture properties of long carbon fiber composites

This paper reports the processing of a carbon fiber reinforced epoxy composite with carbon nanotube integration and examines the potential improvement on the interlaminar toughness. Carbon nanotube enhanced composites were fabricated by spreading a solution of reinforcing nanoparticles between pre-preg layers with the aid of an airbrush. The influence of MWCNTs incorporation has been studied by the End Notched Flexure (ENF) test by means of a new test methodology named Beam Theory including Bending Rotation effects (BTBR) proposed recently. This method allows the determination of the critical energy release rate at each point of the test when stable crack advance occurs, obtaining the R-curve. A maximum increase of 22% in initiation fracture toughness was observed in the samples with functionalized CNTs. Moreover, the propagation fracture toughness increased 14%. (C) 2011 Elsevier Ltd. All rights reserved.