Epoxy nanocomposites with different wt% of alumina was prepared by use of high-speed shear mixer and high-frequency sonicator process, and the electrical and mechanical properties of the materials were investigated. Surface potential variation and trap distribution analysis were carried out with epoxy nanocomposites. Space charge analysis was carried out through Pulsed Electro Acoustic (PEA) technique. The dielectric constant and tan (δ) values of epoxy alumina nanocomposites were measured at different frequencies and temperatures. Contact angle and corona inception voltage caused by a water droplet showed a direct correlation. The viscoelastic properties of the epoxy nanocomposite material were examined through DMA studies. It was concluded that an increase in the supply frequency increases the storage modulus and loss modulus of the epoxy alumina nanocomposites. Glass transition temperature and activation energy increase with an increase in wt% of alumina content in epoxy resin. LIBS analysis indicates that the plasma temperature calculated increases with an increase in the wt% of alumina content in epoxy resin. Also, the measured plasma temperature and hardness of the material showed a direct correlation. © 2020 The Author(s). Published by IOP Publishing Ltd.