聚乙烯/双环戊二烯自修复材料的修复行为特性研究

There are surface defects and micropores in insulation of XLPE cables. The surface defect is caused by the external surface damage of cable joint’s insulation layer and the micropore is caused by electrical, thermal and mechanical damage and distributed in internal insulation layer. These surface defects or micropores may cause partial discharge and even some serious accidents when the cable is in service. However, it is difficult to recognize and eliminate these small defects through existing technology. Therefore, borrowing self-healing ideals of smart materials, this program will prepare microcapsules filled with a healing agent, dicyclopentadiene (DCPD), study the performance improvement method of polyethylene /DCPD self-healing material, and the polyethylene/DCPD self-healing samples will be prepared. By comparing with the XLPE, the trigger modes and conditions, the self-healing ability and the dielectric characteristics at the repair point of polyethylene/DCPD samples will be studied, the law of self-healing behavior and the dielectric characteristics affected by wall of microcapsules will be also researched. Under different concentration, dispersion degree and surface structure of microcapsules, the mechanical properties and electrical insulation properties of the sample will be studied. In combination with molecular modeling method, the micro behavior characteristics of the microcapsule rupture, the DCPD diffusion in polyethylene and the interface characteristics between polyethylene and DCPD will be revealed on the molecular level. The optimization formulation and preparation process of the self-healing polyethylene/DCPD will be proposed. Achievements of this program will promote the development of self-healing materials used in XLPE cables and give brand new ideas for the development of intelligent insulation materials.

XLPE电缆绝缘层内部的微孔和接头处绝缘外表面的划痕，在长期工作条件下容易引发局部放电，甚至导致严重事故。现有检测技术难以发现这类微小缺陷；即使能够发现，目前也无法有效消除。本项目拟借鉴自修复材料理念，以双环戊二烯(DCPD)为修复剂制备纳米/亚微米级微胶囊，进而制备聚乙烯/DCPD自修复材料，研究其性能提升方法；开展对比试验，研究自修复行为的触发机制、修复点处的自修复能力和介电匹配特性，获得微胶囊壁材、壁厚等因素对自修复行为和介电性能的影响规律；研究不同微胶囊浓度、分散程度和表面结构条件下，修复前后试样的机械和电气性能；结合分子模拟，从分子层面揭示修复过程中微胶囊破裂、DCPD在聚乙烯中的扩散和固化、DCPD和聚乙烯间的界面特性等微观行为特性，提出聚乙烯/DCPD自修复材料的优化配方及制备工艺。研究成果将对自修复XLPE电缆的研制具有直接意义，为新型智能电绝缘材料的研制提供全新思路。

聚乙烯电缆在制造、安装及运行过程中，材料内部难免会产生微小损伤缺陷，该类损伤难以被检测及修复，导致电场畸变、材料性能劣化，严重威胁供电安全。因此，本项目以微胶囊及聚乙烯复合材料为研究对象，通过理论分析、试验和仿真等技术手段，研究了聚乙烯/微胶囊复合材料的理化、机械、电气和自修复性能，获得了微胶囊对聚乙烯性能的影响和复合材料的自修复特性，揭示了复合材料典型性能的变化规律和自修复行为的触发机制，探究了复合材料电气性能的修复特性。主要工作和成果有：①通过仿真，获得了微胶囊各项参数对聚乙烯/微胶囊复合材料的应力、裂纹扩展等自修复触发行为的影响规律，确定了合适的微胶囊粒径（100μm左右）和壁厚（2~4μm）等关键参数。改进了微胶囊制备工艺，成功制备出适用于自修复聚乙烯复合材料微胶囊。②探究了聚乙烯/微胶囊绝缘复合材料的制备方案。通过仿真和实验，获得了微胶囊掺杂浓度对聚乙烯复合材料理化、热、机械和电气性能的影响特性，从微胶囊本身及其与基体间的界面特性等方面，揭示了复合材料电气、机械等主要性能的变化机理。③针对聚乙烯电缆典型损伤类型，从机械损伤和电损伤两方面，验证了复合材料的自修复性能。提出了综合材料划痕、电树枝损伤形态结构和击穿场强、极化特性等性能参数的复合材料自修复性能评估方法。④获得了修复产物和聚乙烯之间的界面特性，明确了复合材料的自修复行为及触发机制。研究成果有助于完善自修复材料制备和性能提升方法，为提高供电可靠性提供新思路，并可为聚烯烃类新材料的研发提供有益的借鉴。