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耐电树枝老化特性是表征聚合物绝缘材料介电性能的重要参数之一.聚丙烯(PP)是典型半结晶聚合物,其复杂的非均匀聚集态结构影响电树枝的生长.本文对PP及加入成核剂的PP试样进行了耐电树枝化性能实验,通过偏光显微镜(PLM)及差示扫描量热法(DSC)分析加入成核剂前后PP的结晶形态、结晶度以及结晶结构对电树枝生长特征的影响.以相界面自由能的热驱动作用以及放电雪崩理论为基础,对电树枝生长的热力学和动力学机理进行分析,阐明电场分布对电树枝生长的重要作用.根据半结晶材料的结晶相和非晶相的物理性能,建立材料内部电场分布计算模型,模拟针-板电极条件下聚合物材料内部的局域电场分布情况,分析了电树枝通道的动力学生长特征,探讨了成核剂改变PP的结晶结构抑制电树枝沿电场生长的作用.
The aging resistance of electrical tree is one of the important parameters to characterize the dielectric properties of polymer insulating materials.Polypropylene (PP) is a typical semicrystalline polymer whose complex non-uniform aggregated structure affects the growth of electrical branches.In this paper, The PP samples with nucleating agent were tested for their resistance to electrical dendrites. The morphology, crystallinity and crystalline structure of PP before and after addition of nucleating agent were analyzed by polarized light microscopy (PLM) and differential scanning calorimetry (DSC) The influence of electric field on the growth characteristics of electrical branches is studied.The thermodynamic and kinetic mechanism of electrical branch growth is analyzed based on the thermal driving of free energy at the interface and the avalanche theory of discharge.According to the important role of electric field distribution in the growth of electrical branches, Material crystalline phase and amorphous phase physical properties, the establishment of the internal electric field distribution model of the material to simulate the needle-plate electrode under the local distribution of electric field polymer materials, electric channel dynamics analysis of the characteristics of growth, to explore Nucleating agents alter the crystalline structure of PP to inhibit the electrical tree growth along the electric field.