Space charge and electric treeing resistance properties of MgO/LDPE nanocomposite

Magnesium oxide (MgO)/low density polyethylene (LDPE) nano-composite was prepared by laboratory blending process after MgO nano-powder was treated by silane coupling agent. MgO particles with diameters of about 100 nm were observed to be well dispersed in LDPE by means of high composition contrast scanning electron microscope (SEM) image. The results of space charge distribution measurement by the pulse electro-acoustic (PEA) method revealed that the space charge injection of MgO/LDPE nano-composite was effectively suppressed at 4% MgO in the composite. Meanwhile, at this concentration of MgO, a much higher threshold of space charge injection was found in MgO/LDPE nano-composite by the current voltage characteristic. Electrical treeing breakdown tests indicated a higher tree inception voltage and a restrained tree propagation process in the composite. Interfacial electric charge in the boundary of the nano particles and the polymer matrix was suggested to be responsible for the improvement of electrical properties.