Influence of humidity on the dielectric behaviour of BaTiO3-epoxy composites

Epoxy resin and their particulate composites are widely used in different industries, as aeronautical, automotive, microelectronics and coatings. The water absorption can deteriorate the properties on these materials when they are used in service. Many factors influence in water absorption process, as the quantity of hydroxyls groups, the glass transition temperature of the resin or the presence of a dispersed second phase. Thus, the objective of this work is to determine the dielectric behavior of BaTiO3-epoxy composites in different humid environments (controlled moisture of 80, 50 and 30%) and at room temperature. Results of pure resin samples show that dielectric permittivity increases with the percentage of absorbed water and that this increase is greater for the samples exposed to more humid environments. Interestingly, the addition of ceramic particles not only increases the composite dielectric properties but also reduces the water absorption in all the cases.