Experimental evaluation of viscoelastic and mechanical properties of functionalized multi-walled carbon nanotube and carbon fiber-reinforced epoxy nanocomposite

Carbon nanotubes (CNTs) and carbon fibers are widely used to improve the mechanical and viscoelastic properties of epoxy composites. To achieve this, multiphase systems were used, which combine both and offer superior performance. Amino-functionalized multi-walled carbon nanotubes (MWCNTs) were dispersed in bisphenol-A epoxy using diethyl toluene diamine (DETDA) hardener via sonication and the matrix was reinforced with C8H satin carbon fabric (T-300) at a 65% fiber volume fraction in this study. MWCNTs (0.5, 1, and 2 wt.%) were incorporated to evaluate their influence on three-phase (CNT–epoxy–carbon fiber) composites. Dynamic mechanical analysis (DMA), SEM and micro-tensile testing were also conducted. DMA between room temperature to 190 °C with dual-cantilever and three-point bending was conducted to measure storage modulus (E′), loss modulus (E″) and tan δ. MWCNTs increased tensile strength (1130–1267 MPa) and improved stiffness at low temperatures. E′ decreased and E″ increased with temperature. T_g shifted from 80 °C to 150 °C with frequency. SEM confirmed good MWCNT dispersion, supporting improved mechanical and damping behavior.