Zhang Yuanyuan, Hou Zongke, Wu Kangning, Wang Shihang, Li Jianying, Li Shengtao
State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China.
Materials (Basel). 2020 Apr 29;13(9):2056. doi: 10.3390/ma13092056.
Thermal ageing of cross-linked polyethylene (XLPE) cable insulation is an important issue threatening the safe operation of power cables. In this paper, thermal ageing of XLPE was carried out at 160 °C in air for 240 h. The influence of oxygen diffusion on thermal ageing of XLPE was investigated by Ultraviolet-visible spectrophotometer (UV-Vis), tensile testing, and Fourier transformed infrared spectroscopy (FTIR). It was observed that the degradation degree not only depended on ageing time but also on sample positions. The thermally aged samples were more oxidized in the surface region, presented a darker color, more carbon atoms appeared in the conjugate cluster, had smaller elongation at break and tensile strength, and a larger carbonyl index. As ageing time increased, the non-uniform oxidation of the XLPE samples became more prominent. The degree of non-uniform oxidation caused by oxygen diffusion was quantitatively studied by first order oxidation kinetic. The calculated results demonstrated that carbonyl index measured by FTIR was more sensitive to non-uniform oxidation with a shape parameter in the range of 1-2. The result shown in this paper is helpful for interpreting and predicting the non-uniform ageing behavior of high voltage XLPE cables.
交联聚乙烯（XLPE）电缆绝缘的热老化是威胁电力电缆安全运行的一个重要问题。本文中，XLPE在空气中160℃下进行热老化240小时。通过紫外可见分光光度计（UV-Vis）、拉伸试验和傅里叶变换红外光谱（FTIR）研究了氧扩散对XLPE热老化的影响。观察到降解程度不仅取决于老化时间，还取决于样品位置。热老化样品在表面区域氧化程度更高，颜色更深，共轭簇中出现更多碳原子，断裂伸长率和拉伸强度更小，羰基指数更大。随着老化时间增加，XLPE样品的不均匀氧化变得更加突出。通过一级氧化动力学定量研究了由氧扩散引起的不均匀氧化程度。计算结果表明，FTIR测量的羰基指数对不均匀氧化更敏感，形状参数在1-2范围内。本文所示结果有助于解释和预测高压XLPE电缆的不均匀老化行为。
