Research on space charge distribution in composite of Low Density Polyethylene and Nano Silver

Double-solution mixture method was employed in the preparation of the composite of Low Density Polyethylene/Nano-silver. Space charge distributions in samples with different nano-silver concentrations were measured using the pulsed electro-acoustic (PEA) method. In the experiment, samples were tested under three different levels of electrical stress, respectively: 10kV/mm, 30kV/mm and 50kV/mm. Discharge characteristics of the samples were examined as well. Test results show that the involvement of nano-silver in LDPE causes larger space charge accumulation on the surface of composite samples than pure LDPE sample does. Within the extent of concentrations studied in this paper, it is interesting that concentrations of nano-silver up to 0.04%wt can further enhance interface charge, while lower ones can not. Meanwhile, characteristics of bulk charge in composites are impacted by the introduction of nano-silver. According to the data of the discharge experiment, it is found that the sample with a nano-silver ratio of 0.02%wt has a larger amount of heterocharge near cathode than the sample with a nano-silver ratio of 0.01%wt does. Additionally, samples filled with nano-silver retain about twice more bulk charge than pure LDPE samples, which shows that nano-silver can enhance the depth of traps in composites.

INTRODUCTION

Compared with traditional materials, nano materials have a set of special characteristics, such as surface effect, small size effect, quantum size effect, macroscopic quantum tunneling effect and dielectric confinement effect. Attracted by these outstanding characteristics, a large number of researchers in the field of dielectrics and electric insulation have attempted to add nano materials into polymers in order to improve dielectric and insulating characteristics of polymers. It has already been found that nano-sized fillers can improve some key properties of polymers to a certain extent [1].