外电场对硅烷交联聚乙烯电介质材料分子空间结构影响的分子模拟研究  

Molecular Simulation on Effect of External Electric Field on Molecular Space Structure of Silane Crosslinked Polyethylene Dielectric Material

作　　者：李亚莎[1] 花旭[1] 代亚平[1] 沈星如 王成江[1] LI Yasha, HUA Xu, DAI Yaping, SHEN Xingru, WANG Chengjiang(College of Electrical Engineering and New Energy, China Three Gorges University, Yichang 443002, China)

机构地区：[1]三峡大学电气与新能源学院,湖北宜昌443002

出　　处：《绝缘材料》2018年第10期38-44,共7页Insulating Materials

基　　金：国家自然科学基金资助项目(51577105);三峡大学学位论文培优基金项目(2017YPY038)

摘　　要：为了从分子层面上揭示外电场作用下硅烷交联聚乙烯电缆材料内部分子结构特性的变化情况,采用计算量子化学模拟方法构建硅烷交联聚乙烯分子模型。沿聚乙烯主链方向施加不同大小的电场,分析硅烷交联聚乙烯分子的稳态总能量、偶极矩、分子极化率、电荷分布、能隙和红外光谱变化规律。结果表明:随着电场强度的增大,硅烷交联聚乙烯分子结构发生明显变化。当电场强度达到一定值后,分子稳定结构遭到破坏进而出现断键现象。硅烷交联聚乙烯分子在强电场作用下,主链两端的C-C键和C-H键最先断裂形成自由基。分子内部电荷在电场作用下发生转移,使得聚乙烯链端部C、H原子带电量最大且不断增加,最终导致断键后的C、H自由基带有较高电荷量。这些游离的自由基会形成空间电荷,外电场越大,空间电荷量越大。这些电介质内部微观特性的变化对研究交联聚乙烯电缆的电树枝老化机理具有重要意义。In order to reveal the internal molecular structural property changes of silane crosslinked polyethylene（XLPE） cable material under external electric field at molecular level, a molecular model of silane XLPE was built by computational quantum chemical simulation method. Different intensities of electric field were applied along the main chain of polyethylene, and then the change law of the steady-state total energy, dipole moment, molecular polarizability, charge distribution, energy gap, and infrared spectrum of the silane XLPE were analyzed. The results show that the molecular structure of silane XLPE has obvious change with the increase of electric field intensity. When the electric field intensity reaches to a certain value, the stable molecular structure is destroyed and the bonds break. Under high electric field, the C-C bonds and C-H bonds at the both ends of silane XLPE main chain break at first.and then form free radicals The intramolecular charge would transfer under the effect of electric field, results in the C and H atoms at the ends of polyethylene chain have the largest charge which increase continuously, and finally the C and H free radicals have higher charges after bond breaking. The free radicals would form space charge, and the amount of space charge increases with the increase of external electric field. These resluts have great significance to study the mechanism of electrical tree ageing in XLPE cables.

关 键 词：交联聚乙烯材料 外电场 空间电荷 自由基 分子模拟 

分 类 号：TM215.1[一般工业技术—材料科学与工程]