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为研究纳米颗粒填充对复合介质阈值电场特性的影响,以低密度聚乙烯(low-density polyethylene,LDPE)为基料、纳米二氧化硅(silica)为填充颗粒,制备了填充粒径分别为7和16 nm、填充浓度在0~5.0%范围的LDPE/silica纳米复合介质,并测试了复合介质的准稳态直流电导。研究表明:低电场下纳米颗粒对复合介质直流电导的影响不大;在高电场下,低填充密度(1.0%附近)时复合介质的电导比纯LDPE的值大,阈值电场均低于纯LDPE的值;仅当填充浓度较高时,复合介质的电导才下降,并且阈值电场高于纯LDPE的值。纳米颗粒填充粒径7和16 nm时,纳米复合介质的阈值电场特性基本一致,但在高电场下,填充粒径7 nm时的复合介质电导小于填充粒径为16 nm的值,且填充粒径7 nm时复合介质的阈值电场都高于填充粒径为16 nm时的值,表明填充粒径越小的纳米颗粒越能提升复合介质的阈值电场。另外,基于空间电荷限制电流理论(space charge limitedcurrent,SCLC)分析可知:纳米颗粒填充浓度较低时,纳米复合介质中总陷阱浓度H相对于纯LDPE都明显下降,仅当填充浓度进一步升高时,总陷阱浓度H才高于纯LDPE中的值。填充浓度在0.1%~5.0%时,纳米复合介质内部总陷阱浓度H随填充浓度的升高而升高,这主要与纳米颗粒引入颗粒/基料界面结构的增多有关。
In order to study the effect of nanoparticle filling on the threshold electric field properties of composite media, low-density polyethylene (LDPE) as base material and silica as filler were prepared. And 16 nm, filled with LDPE / silica nanocomposite at a concentration of 0 ~ 5.0%, and the quasi-steady-state DC conductance of the composite was tested. The results show that under low electric field, the nanoparticles have little effect on the DC conductance of the composite medium. Under low electric field, the conductance of the composite medium is higher than pure LDPE at low packing density (around 1.0%), and the threshold electric field is lower than pure LDPE The conductance of the composite medium only decreases when the fill concentration is higher and the threshold electric field is higher than the value of pure LDPE. At 7 and 16 nm, the threshold electric field properties of nanocomposite were basically the same. However, under the high electric field, the conductivity of the composite medium with the diameter of 7 nm was smaller than that of the filled particle with a diameter of 16 nm. The threshold electric field of the composite at 7 nm was higher than that at 16 nm, which indicated that the smaller the filled particle size, the more the threshold electric field of the composite could be promoted. In addition, based on space charge limited current (SCLC) analysis, it is found that the total trap concentration H in nanocomposite decreases significantly compared with pure LDPE when the concentration of nanoparticle is low, and only when the concentration is further increased , The total trap concentration H is higher than in pure LDPE. The concentration of total trap H in the nanocomposite medium increases with the concentration of the filler at the concentration of 0.1% -5.0%, which is mainly related to the increase of the particle / binder interface structure introduced by the nanoparticles.