| The rapidly growth of grid promotes the development of cable industry. As the main components of the DC power cable insulation materials, the properties of PE play an important role in the service life and the environmental suitability of the cable. During the process of dc cables, cross-linking agent and antioxidant are added into the material. Cross-linking process improves the working temperature and antioxidant delays the aging time of oxidation. In this paper, SiO2/LDPE nanocomposite with different addictive were prepared, in order to compare the effect of different fillings, cross-linking agents and antioxidant on dielectric properties at variety temperatures. To study the dependence of materials and impact factors, conductivity characteristics, space charge and dc breakdown strength were discussed.Nine kinds of materials were prepared by melt blending method. The samples were processed via plate vulcanizing machine. The physical structure and chemical composition of the materials were characterized and analyzed by SEM, FTIR and X-ray diffraction.To discuss the influence of filler concentration of SiO2/LDPE, it adopts the filler concentration 0%?1%?2% and 3% in this paper. Along the increase of temperature the conductivity of four materials are gradually increased. The results showed that the conductivity of nanocomposites is smaller than the LDPE, with the increase of adding the conductivity decreases significantly. Especially in high electric field at high temperature, for example 90 under 40 k V/mm, the conductivity of 1wt%SiO2/LDPE is an order of magnitude higher than 3wt%SiO2/LDPE. Compared with LDPE, the inhibition of space charge of nanocomposites is higher, which 1wt%SiO2/LDPE has the strongest inhibition. What's more, the adding of nano SiO2 improves the dc breakdown strength. Loading from 1% to 2%, the dc breakdown strength is reduced, while loading from 2% to 3%, the dc breakdown strength increases. But four kinds of material have the same dc breakdown strength at 90??In order to study the influence of DCP and antioxidants on dielectric properties of 1wt% SiO2 nanocomposite, six kinds of materials were prepared by melt blending method. Firstly, it can improve the conductivity of the material and aggravate the accumulation of space charge with the adding of cross-linking agent. But the effect of DCP can enhance the dc breakdown strength obviously, especially at high temperature. Secondly, the effect of antioxidant shows two kinds of results: one is from XLPE, which conductivity and space charge increase and dc breakdown strength reduces, the other is from SiO2/LDPE and SiO2/XLPE. The influence on conductivity is little, which also on space charge inhibition. But the effects on dc breakdown strength is obvious. The results show that SiO2/XLPE with antioxidant has the strongest dc breakdown strength. To figure out the reason of such increase, it is believed that crosslink process help boost positive effect compared to SiO2/LDPE, and the introduction of nano SiO2 enhanced the strength compared to XLPE. |
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