Dielectric and thermal properties of epoxy resins with TiO₂ nanowires

Epoxy based composites with reinforced dielectric properties were successfully synthesized by using TiO₂ nanowires as inorganic filler. TiO₂ nanoparticle/epoxy composites were also prepared as a contrast. TiO₂ nanowires were synthesized by a hydrothermal method, with an average diameter of 50 nm and a length of 5 µm. TiO₂ nanoparticles were purchased with average diameter of ~60 nm. Scanning electron microscopy images show that two types of fillers are both homogeneously dispersed in the matrix. Although the specific surface area of TiO₂ nanoparticles is about twice of that of TiO₂ nanowires, remarkable improved dielectric constant, enhanced electrical and thermal conductivity, higher space charge accumulation and stronger charge carrier mobility were observed in nanowire filled epoxy resin at the same filler content. Meanwhile, nanowires composites exhibit excellent glass transition temperature and thermal stability. These results indicated that the geometry of filler had a profound impact on the performance of epoxy composites, and nanowire filling is more effective than nanoparticle filling to enhance the properties of epoxy resin.