不同交联度下复合绝缘子用环氧树脂热力学性能分子动力学模拟

Molecular Dynamics Simulation of Thermo dynamic Properties of Epoxy Resin for Composite Insulator Under Different Crosslinking Degrees

复合绝缘子已在我国交直流输电工程中得到广泛应用,然而运行过程中冷热冲击、极端温度、机械应力都会加速其绝缘老化,并且芯棒部分易出现微小缺陷成为绝缘薄弱环节。交联度是影响环氧树脂内部交联结构的重要因素之一,研究交联结构与环氧树脂热力学性能之间的关系,对于提升其绝缘可靠性具有重要意义。因此本研究基于分子动力学的方法,构建了不同交联度的双酚A环氧树脂模型,从微观角度分析了交联度对环氧树脂热学力学性能的影响。结果表明,随着交联度的不断提高,其热学力学性能提升较为明显。从分子角度来讲,交联度的增大提升了环氧树脂内聚能密度,降低体系的均方位移与自由体积占比。结构参数的改变不仅从分子角度解释了不同交联度对环氧树脂热力学性能的影响,更为探究复合绝缘子老化机理提供了理论基础。

Composite insulators have been widely used in AC and DC transmission projects in China.However,during operation,cold and heat shock,extreme temperature and mechanical stress will accelerate their insulation aging,and small defects are easy to appear in the core rod,which becomes the weak link of insulation.Crosslinking degree is one of the important factors affecting the internal crosslinking structure of epoxy resin.The study on the relationship between crosslinking structure and thermodynamic properties of epoxy resin is of great significance to improve its insulation reliability.Therefore,based on the method of molecular dynamics,the bisphenol A epoxy resin model with different crosslinking degrees was constructed,and the effects of different crosslinking degrees on the thermodynamic properties of epoxy resin were studied from the molecular point of view.The results show that with the increase of crosslinking degree of epoxy resin model,its thermal and mechanical properties are obviously improved.From the microscopic point of view,the increase of crosslinking degree improves the cohesive energy density and reduces the ratio of mean square displacement and free volume.The change of structural parameters explains the influence of different crosslinking degrees on the thermodynamic properties of epoxy resin,providing a theoretical basis for exploring the aging mechanism of composite insulators.