聚乙烯陷阱特性对真空直流沿面闪络性能的影响

介绍在低密度聚乙烯中添加成核剂酚酞,研究半结晶聚合物的结晶行为、显微结构、陷阱参数以及真空直流沿面闪络性能之间的关联。扫描电镜及差式扫描量热测试结果表明,酚酞掺杂明显改变了低密度聚乙烯的结晶行为及显微结构,增加了结晶度及片晶厚度,减小了球晶尺寸,并使球晶分布更加均匀。热刺激电流结果表明,酚酞掺杂在低密度聚乙烯中引入了更多的深陷阱,增加了α及γ陷阱的深度。分析聚乙烯结晶行为与陷阱之间的关系表明,低密度聚乙烯的陷阱深度随球晶尺寸减小而增大,陷阱密度随结晶度增大而减小。酚酞改性后试样的真空沿面闪络电压整体有所提升,最高提升了48.42%。分析陷阱深度及陷阱密度与闪络电压之间的“U”型关系,认为陷阱深度及陷阱密度在影响闪络性能过程中起着相互协调、配合及转化的作用。

Influence of Trap Characteristics on DC Surface Flashover Performance of LDPE in Vacuum

the paper studies the relationship between crystallization behavior,microstructure,trap parameters,and vacuum surface flashover performance of semi-crystallinity polymers through adding phenolphthalein in LDPE as nucleating agent.Scanning electron microscope(SEM)and scanning calorimeter(DSC)results show that phenolphthalein modification greatly changes the crystallization behavior and microstructure of LDPE,that is increasing the crystallinity and lamella thickness,decreasing the spherulite size and making grains distribute more uniformly.Thermally stimulated depolarization current(TSDC)results indicate that both the shallow trap(γpeak)and the deep trap(αpeak)become deeper with the increase of phenolphthalein concentration.Relationship between structure and trap indicates that smaller spherulite size indicates the deeper trap,and larger crystallinity means smaller trap density.Surface flashover performance has been improved after phenolphthalein modification,and the highest value is increasing by 48.42%.Finally,it is concluded that trap level and trap density play complementary,cooperation and mutual transformation roles in improving the surface flashover performances after analysis the U-shaped relationship between trap parameters and flashover voltage.