Controlling off-axis stiffness and stress-relaxation of carbon fiber-reinforced polymer using alumina nanoparticles

This investigation experimentally examines the effect of incorporating alumina nanoparticles on the off-axis stiffness and stress-relaxation of carbon fiber-reinforced polymer composites. Four epoxy–alumina nanoparticle nanocomposites incorporating 0.0, 1.0, 2.0, and 3.0 wt% alumina nanoparticles of the total weight of epoxy are examined. Off-axis tension stiffness and stress-relaxation tests were performed on carbon fiber-reinforced polymer coupons fabricated with alumina nanoparticles–epoxy nanocomposites. Dynamic mechanical analysis testing of neat epoxy and epoxy nanocomposites incorporating alumina nanoparticles was used to identify the stiffness and relaxation behavior of the alumina nanoparticles–epoxy nanocomposite matrix. Fourier transform infrared spectroscopy was used to observe chemical changes when alumina nanoparticles are mixed with epoxy. It is shown that using alumina nanoparticles at a concentration close to 2.0 wt%, can reduce the off-axis stiffness by ∼30% and increase the off-axis str...