Effects of Nanotube/Matrix Interface on Multi-Walled Carbon Nanotube Reinforced Polymer Mechanical Properties

In this paper, experimental and Finite Element Methods have been used to determine mechanical properties of nanocomposites. Standard tensile and compression samples with 0.0, 0.15, 0.25, 0.35, 0.45, and 0.55 weight fraction of Multi-Walled Carbon Nanotube (MWCNT) were prepared and tested. Nanotube weight fraction was varied to investigate the effects of nanotube weight fraction on nanocomposite mechanical properties. Mechanical properties such as: modulus of elasticity, yield strength, ultimate tensile strength, and fracture strain were determined experimentally. Experimental results showed that incorporation of carbon nanotubes improves modulus of elasticity, and yield and ultimate strengths of the epoxy resin under tension and compression. Results also showed that fracture strain decreases drastically with increasing nanotube weight fraction. Field Emission Scanning Electron Microscope (FESEM) was used to obtain images of the samples’ fracture surfaces. These images showed a good MWCNT dispersion in the matrix. Also, numerical simulations were conducted in Abaqus software. In these simulations, the effects of the interface between individual nanotubes and the outer nanotube and matrix were investigated. Two different models were used for these interfaces. Connector constraints were used in the first model and thin shells in the second model. The connector model predicted lower mechanical properties compared to the thin shell interface model. Finally, experimental and numerical results were compared and a good correlation was observed between the results.