Mechanical properties of multiwall carbon nanotube-Epoxy composites

Composites containing epoxy resin and functionalized multiwall carbon nanotubes with different mass concentrations were preparedby ultrasonic homogenization followed by curing at room temperature. Mechanical characterizations of composites reveal a general improvement of the flexural strength at tensile stress and Young’smodulus at low concentrations of nanotubes, the enhancement of mechanical properties compared to pure epoxy resin being observed for carbon nanotube concentrations up to 4 wt. %. The tensile strength at tensile stress decreases slowly with increasing the concentration of nanotubes. Numerical simulations of flexural behavior agree with experimental data for a lower-than-unity polymerization degree, the un-completed curing process hypothesisbeing also supported by electrical measurements. Electrical measurements reveala strong decrease of the resistivity of the composites with the MWCNT content with no reproducible values above room temperature in heating-cooling cycles.