Effect of space charge in nanocomposite of LDPE/TiO2

Nanocomposite of low density polyethylene (LDPE)/TiO₂ was prepared via solution blending method. The disperse performance of TiO₂ in LDPE was observed with Scanning Electron Microscope. It is shown that TiO₂ could be dispersed uniformly in LDPE through controlling temperature and content of the solution of LDPE, and the largest conglomeration diameter of TiO₂ in LDPE is less than 80 nm. At the same time, space charge distribution of samples with and without nano TiO₂ was measured with Pulsed Electroacoustic Method. Hetero-polar space charge near electrodes is much less in sample of nanocomposite of LDPE/TiO₂ than that in pure LDPE under lower direct current (DC) stress (no more than 40 kV/mm), and space charge in the central of sample of LDPE/TiO₂ is much more uniform than that in pure LDPE. Thus electrical stress concentration is improved under DC stress in LDPE/TiO₂. After being pre-stressed under stress of 50 kV/mm for 1h, samples with and without nano TiO₂ were short-circuited, and space charge in these samples was measured. It is shown that decaying rate of the remnant of space charge in LDPE sample containing TiO₂ increases with increasing of the TiO₂.