【摘要】 绝缘材料的电树枝生长特性分析是评估其绝缘性能的重要方法之一。采用熔融插层复合法制备了一种低密度聚乙烯–蒙脱土纳米复合材料,设计制作了纳米复合材料的电树枝生长试样及实验系统,在实验中观测了恒定电压下试样中电树枝生长过程及电树枝形态,测量了试样中电树枝的生长速度与扩散系数,分析了电树枝的局部放电统计特性。通过分析低密度聚乙烯–蒙脱土纳米复合材料的结晶行为,说明了纳米蒙脱土对该纳米复合材料中电树枝的抑制机制。实验与分析结果表明:纳米蒙脱土粒子有效提高了低密度聚乙烯的结晶度并减小了晶粒尺寸。同时,纳米蒙脱土粒子有利于降低纳米复合材料电树枝局部放电量与放电重复率,延缓了电树枝的引发与生长。更多还原

【Abstract】 Analysis on growth properties of electrical trees in insulation material is an important approach to evaluate its performances. This paper presents a type of low-density polyethylene (LDPE)-montmorillonite (MMT) nano-composite prepared by a melting intercalation process. A testing system and specimens of electrical trees growing in the nano-composite were designed and made. Growth process and morphology of electrical trees in these specimens were observed in the experiments under a constant voltage stress. Growth rates and expansion coefficients of the electrical trees in the specimens were measured and statistical characteristics of partial discharges (PDs) in electrical trees were analyzed. The mechanism of electrical trees in the LDPE-MMT nano-composites restrained by MMT nano-particles was illustrated through analysis of crystallization behavior of the nano-composites. Experiments and analysis results showed that MMT nano-particles improve the crystallinity degrees and decrease the grain sizes of LDPE. Meanwhile,MMT nano-particles are helpful to reduce quantities and repetition rates of PDs in electrical trees of the nano-composite and to postpone inception and growth of the electrical trees.更多还原