交联行为对纳米复合电介质电导特性和电气强度的影响

Effect of Crosslinking Behavior on Conductivity Characteristics and Electric Strength of Nanocomposite Dielectrics

为了研究交联行为对纳米复合材料电导特性和电气强度的影响,采用熔融共混法分别制备了聚乙烯/蒙脱土(PE/OMMT)和交联聚乙烯/蒙脱土(XLPE/OMMT)纳米复合材料,研究了有机化蒙脱土(OMMT)在聚合物中的层间距变化和分散状态,对复合材料的体积电阻率和工频电气强度进行了测试。结果表明:OMMT在聚乙烯(PE)基体中的层间距大于在交联聚乙烯(XLPE)中的层间距。当OMMT质量分数为2%时,蒙脱土在聚乙烯中呈现出良好的剥离分散状态。纳米复合材料的体积电阻率随温度升高而减小,其活化能的大小与有机化蒙脱土的插层效率有关。OMMT的加入明显提高了PE的电气强度。而交联后由于三维网状结构的建立,较强的分子间作用力减小了OMMT的层间距,使OMMT的分散均匀性变差,导致交联后复合电介质的电气强度相比交联前有所降低。

In order to study the effect of crosslinking behavior on the conductivity characteristic and electric strength of nanocomposites, polyethylene/montmorillonite(PE/OMMT) and crosslinked polyethylene/montmorillonite(XLPE/OMMT) nanocomposites were prepared by melting blending method, respectively.The interlayer spacing variation and dispersion state of organic montmorillonite(OMMT) in polymer were studied. The volume resistivity and AC electric strength of the composites were tested. The results show that the interlayer spacing of OMMT in polyethylene(PE) is larger than that in crosslinked polyethylene(XLPE). When the mass fraction of OMMT is 2%, the OMMT can be well dispersed in the polyethylene. The volume resistivity of nanocomposites decreases with the increase of temperature, and their activation energy are related to the intercalation efficiency of OMMT. With the addition of OMMT, the electric strength of PE increases significantly. While after PE is crosslinking and the three-dimensional network structure is built, the interlayer spacing of OMMT decrease because of the strong intermolecular force, making the dispersion uniformity of OMMT become worse, leading to the electric strength of composite dielectrics decrease after crosslinking.