中文摘要：

为研究纳米颗粒填充浓度对复合介质内部空间电荷特性的影响，以低密度聚乙烯（10w．density polyethylene，LDPE）为基料，纳米二氧化硅（Silica）为填充颗粒，制备了浓度在0％-5％范围的纳米LDPE／Silica复合介质，并测试了复合介质的准稳态直流电导和空间电荷分布。当LDPE内填充不同浓度的纳米silica后，复合介质内部的平均体空间电荷密度均得到有效抑制，且其平均衰减速度随填充浓度的升高而下降，但复合介质的准稳态直流电导在填充浓度低于0．5％时比纯LDPE时要大，当填充浓度高于0．5％时，准稳态直流电导随着填充浓度的升高而快速下降。结果表明试样内部的空间电荷分布存在3种趋势：当纳米silica填充浓度为0％～0．1％时，试样内表面侧的异极性空间电荷量随填充浓度升高而下降；当填充浓度为0．5％～2％时，试样内表面侧积累同极性电荷，并随填充浓度升高而增大；当填充浓度高于2％时，同极性空间电荷量下降。最低空间电荷密度和准稳态直流高场电导对应的纳米填充浓度分别为0．5％和5％，表明在应用纳米颗粒对聚合物的绝缘性能改良时，为获得最佳的介电性能，应根据实际需求来选择适当的填充浓度。

英文摘要：

The nano-filler concentration effect on space charge behavior is investigated through the measurement of high field conduction and space charge distributions in low-density polyethylene （LDPE） and LDPE/silica nanocomposites filled with nanosilica from 0 to 5.0%. It is found that the amount of mean volume density of space charge reduces after filled with nanosilica in LDPE and the mean attenuation rate of space charge reduces with increasing of nanosilica concentration. However, the high field conduction distinctly increases in nanocomposites filled with low concentration nanosilica, below 0.5%. And then it decreases with the increase of filler concentration. Three different trends of space charge distribution are confirmed in nanocomposites. In low concentrations from 0 to 0.1%, the amount of these heterocharge reduces with the increase of fillers concentration. In the concentrations from 0.5% to 2%, homocharge accumulates close to anode and cathode. When the concentration increases to 2%, the amount of homocharge reaches a maximum and then reduces with the increase of concentration. The concentration for the lowest high field conduction current density and minimum amount of space charge formed in nanocomposite is different, i.e. 5% and 0.5%, respectively. It is considered that the optimum nanosilica concentration should be selected based on the designing target.