The dispersion state of nanoparticles affects the properties of composites, and the crosslinking process of polymers affects the dispersion state of nanoparticles. In order to investigate the effects of crosslinking behaviour on the water-tree ageing characteristics of nanocomposite dielectrics at the molecular level, polyethylene/organic-montmorillonite (PE/organic montmorillonite (OMMT)) and crosslinked polyethylene/organic-montmorillonite (XLPE/OMMT) nanocomposites were prepared by the melt blending method, after which the accelerated water-tree ageing experiments were conducted using a needle electrode. Fourier transform infrared spectroscopy, differential scanning calorimetry, successive self-nucleation annealing and scanning electron microscope (SEM) tests were conducted to characterise the properties of the samples before and after water-tree ageing. The results indicate that the initiation probability and the length of water trees in XLPE/OMMT are less than those in PE/OMMT. The carbonyl index in the water-tree area of the two nanocomposites increases, indicating that the water-tree ageing is the result of electrochemical degradation. The crystallisability of the water-tree area degrades, decreasing the crystallinity and the lamellar thickness. The growth of water trees destroys molecular chains and crystal structures, which results in local cracks. There are many holes for the water tree growth in the PE/OMMT specimen. However, the crosslinked meshwork not only restricts the movement of macromolecular chains but also increases the stability of the lamellar barrier effect of OMMT. The combination of the two effects significantly improves the water-tree resistance of the XLPE/OMMT nanocomposite.

中文翻译：

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聚乙烯/有机蒙脱石及交联聚乙烯/有机蒙脱石纳米复合材料的水树老化特性研究

纳米粒子的分散状态影响复合材料的性能，聚合物的交联过程影响纳米粒子的分散状态。为了在分子水平上研究交联行为对纳米复合电介质水树老化特性的影响，聚乙烯/有机蒙脱石（PE/有机蒙脱石（OMMT））和交联聚乙烯/有机蒙脱石（XLPE/OMMT）通过熔融共混法制备纳米复合材料，然后使用针电极进行加速水树老化实验。傅里叶变换红外光谱、差示扫描量热法、进行了连续的自成核退火和扫描电子显微镜（SEM）测试，以表征水树老化前后样品的性能。结果表明，XLPE/OMMT 中水树的起始概率和长度小于 PE/OMMT 中的水树。两种纳米复合材料的水树区域的羰基指数增加，表明水树老化是电化学降解的结果。水树区域的结晶能力降低，降低了结晶度和层状厚度。水树的生长破坏了分子链和晶体结构，从而导致局部裂缝。PE/OMMT 标本中有许多供水树生长的孔。然而，交联的网状结构不仅限制了大分子链的运动，还增加了OMMT层状屏障效应的稳定性。这两种效应的结合显着提高了 XLPE/OMMT 纳米复合材料的抗水树性。