【作者】 王颖；

【Author】 Ying Wang;State Key Laboratory of Rare Earth Resource Utilization,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences;

【机构】 中国科学院长春应用化学研究所；

【摘要】 交联聚乙烯（XLPE）绝缘材料在高压电缆行业得到广泛应用,电树枝老化是导致高压电缆XLPE绝缘性能劣化的主要因素之一,限制了XLPE绝缘电缆的应用。据文献报道,添加SiO2、MgO、ZnO、Al₂O₃、TiO₂、C₆₀和PCBM等可以有效地防止电树枝化和提高击穿强度。但是,由于实验手段的限制,纳米粒子的作用机理尚不明晰。因此,本论文应用紧束缚密度泛函理论计算方法,研究了一系列金属和非金属氧化的电离能、电子亲和势和相对的跃迁难易程度等电学性质,并采用基于紧束缚密度泛函理论的量子化学分子动力学模拟,以Si O2和聚乙烯混合的体系为代表,研究了纳米粒子与聚乙烯之间的微观分子反应机理,揭示了纳米粒子由于电负性的不同优先捕获电子的能力,阐明了尺寸效应的影响,指出了纳米粒子填充提高聚乙烯电树枝化初始时间和初始速度的本质原因,为XLPE在500 k V以上电缆中的应用提供可靠的理论依据。更多还原

【Abstract】 Quantum chemical molecular dynamics（QM/MD） simulations on SiO₂ filling in the polyethylene（PE） showed that: in the absence of SiO₂, the PE was quickly charged by the high-energy electrons, which resulted in C-C or C-H bonds breaking; On the contrary, in the presence of SiO₂ nanoparticles, electrons trapping and accumulating were dominated by SiO₂ nanoparticles, which made polyethylene be preferentially protected and the initial time of electrical treeing was increased. Furthermore, compared with all investigated nanoparticles, SiO₂ was regarded as the most promising candidate attributing to the highest electron affinity. We further observed that once the high-energy electrons were supersaturated in the nanoparticles, the polyethylene chains would be unavoidably charged and C-H bonds breaking occurred. Following that the polyethylene chains decomposing and cross-linking were involved into the initial growth of electrical treeing. The current observation can be potentially used in power cable insulation.更多还原