Effect of nano-additive size on the space charge behaviour in LDPE/SiO2 nanocomposite

The distribution of space charge in polymer nanocomposite material is related to the properties of nano-additive, such as size. In this paper, nanocomposites of low-density polyethylene (LDPE) and nano-SiO₂ with different size were prepared, respectively. The space charge behaviors of all samples were investigated with pulsed electro-acoustic method (PEA). After pre-stressing under an electric stress of 50 kV/mm for 1 h, samples filled with different size of nano-SiO₂ were shorted, and space charge was measured. It is shown that the distribution and amount of space charge in the nanocomposites has a strong relation relation with the size of nano-SiO₂. The potential barrier between nanocomposite and electrodes materials attenuates with decreasing of nano-SiO₂ size. And the mean attenuation rate of space charge decreases when the pure LDPE is filled with nano-SiO₂. However, the mean attenuation rate of LDPE/SiO₂ rises with increasing of nano-SiO₂ size.