Effect of water absorption on the mechanical and dielectric properties of nano-alumina filled epoxy nanocomposites

Spherical alumina (Al2O3) nanoparticles were incorporated into diglycidyl ether of bisphenol A (DGEBA) epoxy resin. The objective of this study is to investigate the effect of water absorption on the mechanical and dielectric properties of the Al2O3/epoxy nanocomposites. The results from tensile tests indicate that the incorporation of the Al2O3 nanoparticles into the epoxy can improve the stiffness of the matrix. DMA results show that the stiffness improvement is more pronounced at the rubbery state of the matrix. The Al2O3 nanoparticles can increase the dielectric constant of the epoxy resin due to the increase in the total interfacial area. Upon water absorption, the mechanical properties of the Al2O3/epoxy nanocomposites decrease evidently, because of the damage of water on the epoxy resin. However, the ductility can be improved by the water absorption process. In addition, both dielectric constant and dielectric loss of the Al2O3/epoxy nanocomposites increases greatly after water absorption treatment.