Development of new toughening modified dielectric epoxies

In this paper, the epoxy is toughening modified by adding polyester (PET) and nano-Al₂O₃ particles, both dielectric and mechanical properties of the modified epoxies are examined. The influence of the frequency of electric field and temperature on dielectric loss, and the effect of the nano-particles addition on impact strength, tensile strength and modulus are investigated. The experimental results showed that: the impact toughness, tensile strength and modulus of the modified epoxies are remarkable greater than those of pure epoxy resin. Dielectric losses of the modified epoxies are of the order of 10^-4 in magnitude when temperature is less than 393K. A peak phenomenon appears when the testing temperature is increased between 393-413K. The dielectric loss is dramatically reduced and becomes a constant with increasing of electric field's frequency.