Experimental investigation on the effects of carbon nanotubes on mode I interlaminar fracture toughness of laminated composites

In this research, a small quantity of multiwalled carbon nanotubes was used in order to enhance the IFT and the tensile properties of glass fiber/epoxy composite laminates. For this purpose, the nanocomposite samples, which have 18 fiber-glass plain-weave layers were manufactured. The epoxy resin system is made of Epon828 resin with Epikure F205 as the hardener. The MWCNTs modified with hydroxide (-COOH) is also dispersed into the epoxy system as a reinforcement in a 0, 0.1, 0.5, and 1wt%. In addition, the tensile nanoresin and hybrid nanocomposite specimens were produced. In the tensile test of nanomatrixes, the maximum change in Young's modulus, ultimate strength, and fracture toughness of the samples is obtained in the 0.5 wt% sample, with a 31.2, 21.4, and 16.66% increase with respect to neat sample, respectively. Moreover, the results of the tensile test of hybrid nanocomposites show that the maximum change in fracture toughness, ultimate strength, and fracture strain of the samples is in the 0.5wt% sample, with a 12.6, 9.8, and 12.6% increase with respect to the neat sample, respectively. The result of the double cantilever beam test of hybrid nanocomposites indicates that the maximum change in value of the force and value of the energy of crack propagation in mode I interlaminar fracture is in 0.5wt% sample, with a 24.4 and 24.15% increase respect to the neat sample, respectively. Totally, it can be included that the 0.5wt% is the best value out of 3% of MWCNTs to be added. POLYM. COMPOS., 39:E797-E806, 2018. (c) 2016 Society of Plastics Engineers