Nano-Reinforcement effects on damping properties of polymeric composite materials under different environmental conditions

Silica, alumina and carbon nanoparticles were dispersed into epoxy resin with anultrasonic liquid processor at 0.5, 1.5 and 3wt% content. Hardness, tensile anddynamic tests were carried out on these nanocomposites in comparison to neatepoxy. The hardness test shows that the addition of nanoparticles to epoxy resinincreases the hardness over neat epoxy. The hardness and tensile strength areimproved by adding 0.5wt% silica, 0.5wt% alumina and 1.5wt% carbonnanoparticles. The tensile modulus increases as the nanoparticle contentincreases. Further comparison of the theoretical predictions with experimentalmoduli show acceptable prediction models. The effect of adding nanoparticles inaddition to the effect of varying moisture content on the dynamic behavior ofnanocomposites was investigated.Results indicate that addition of nano powders tends to lower moistureabsorption of epoxy except for the 1.5wt% and 3 wt% alumina and silicananocomposites. Damping results show that dry silica and aluminananocomposite have lower damping capability than dry neat epoxy at highfrequencies. At half saturation, the loss factor of nanocomposites is higher thanthose determined under dry and saturated conditions. As the moisture reachesthe saturation level the loss factor reduces. However, the damping behavior ofsome epoxy nanocomposites improves as a result of water absorption especiallyat high frequencies.