Ahmed Muneeb, Zhong Lisheng, Li Fei, Xu Nuo, Gao Jinghui
State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China.
Materials (Basel). 2022 Aug 25;15(17):5857. doi: 10.3390/ma15175857.
In this research, crosslinked polyethylene (XLPE) is developed with selective content of dicumyl peroxide (DCP), and the influence of microstructural properties and chemical composition on the mechanical and direct current (DC) dielectric properties are investigated. The measurements for the microstructural analysis are taken by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), gel content test and Fourier transform infrared (FTIR). The mechanical properties of XLPE are evaluated by hot-set test. The results of microstructural and chemical composition show that the increase in DCP content increases the crosslinking degree from 74.3% to 81.6%, reduces the crystallinity/lamella thickness from 36.8% to 35.5%/7.6-7.1 nm, reduces the average molecular weight between two crosslinks by 0.01 kg/mol and reduces the oxidation level/carbonyl index. The increase in DCP in XLPE samples decreases the permanent elongation from 2.2% to 0% and elongation rate from 300% to 80% of the cable insulation. The rise in DCP content increases the crosslinking degree due to which the DC resistivity and activation energy is increased. The DC breakdown strength at 30-90 °C is increased due to the increase in crosslinking degree and reduction in carbonyl index/oxidation level. The space charge accumulation is measured at 30 °C under 20-60 kV/mm, resulting in less homo-charges and hetero-charges with the increase in DCP. It is proven that the role of appropriate DCP content is vital in increasing the DC dielectric performance, internal material characteristics and mechanical performance of XLPE.
在本研究中，制备了含有特定含量过氧化二异丙苯（DCP）的交联聚乙烯（XLPE），并研究了微观结构特性和化学成分对其力学性能和直流（DC）介电性能的影响。通过凝胶渗透色谱法（GPC）、差示扫描量热法（DSC）、凝胶含量测试和傅里叶变换红外光谱法（FTIR）对微观结构进行分析测量。通过热定型试验评估XLPE的力学性能。微观结构和化学成分的结果表明，DCP含量的增加使交联度从74.3%提高到81.6%，使结晶度/片晶厚度从36.8%降低到35.5%/7.6 - 7.1 nm，使两个交联点之间的平均分子量降低0.01 kg/mol，并降低了氧化水平/羰基指数。XLPE样品中DCP含量的增加使电缆绝缘的永久伸长率从2.2%降低到0%，伸长率从300%降低到80%。DCP含量的增加提高了交联度，从而提高了直流电阻率和活化能。由于交联度的提高和羰基指数/氧化水平的降低，30 - 90°C下的直流击穿强度有所增加。在30°C、20 - 60 kV/mm条件下测量空间电荷积累，结果表明随着DCP含量的增加，同电荷和异电荷减少。结果证明，适当的DCP含量对于提高XLPE的直流介电性能、内部材料特性和力学性能至关重要。
