The thermally stimulated currents of SiO2/ low-density polyethylene micro- and nanocomposites

Composite samples of low-density polyethylene (LDPE)/ nano-SiO₂ and LDPE/ micro-SiO₂ were prepared with a method of double-solution mixture, respectively. Depolarization currents of all samples were investigated with thermally-stimulated current. It is found that the currents of both composites increase with the loading level of nano-SiO₂ and/or micro-SiO₂, and the peak width of each composite is greater than that of pure LDPE. In addition, the peak location of the nanocomposite shifts as the loading level increases, while that of the microcomposite does not shift significantly. For the sake of understanding activation energy of both composites and pure LDPE, a method of initial rise method was used to analyze the depolarization current. It is found that LDPE has the greatest activation energy among all samples and the activation energy of both composites decreases with the increase of the loading level. Moreover, the activation energy of the nanocomposite is less than that of the microcomposite at the same loading level. As the nano-SiO₂ loading level reaches 5.0% wt, the nanocomposite has the least activation energy of 0.25 eV.