中压聚丙烯和交联聚乙烯绝缘材料的结构与性能对比

Comparison of Structure and Performance of Medium Voltage Polypropylene and Cross-linked Polyethylene Insulation Material

热塑性聚丙烯材料具有优异的电气性能和热性能,用于生产电力电缆绝缘,其生产过程中无需交联和脱气,能耗低、可回收,与交联聚乙烯相比具有良好的环境友好性。本文以中压聚丙烯电缆和交联聚乙烯电缆绝缘为研究对象,通过差示扫描量热分析、傅里叶红外光谱分析、X射线衍射分析方法对直接合成的聚丙烯和交联聚乙烯的结构进行研究对比,并对其力学性能、介电常数和介质损耗、电气强度等宏观性能进行测试。结果表明:直接合成的聚丙烯分子链上穿插了乙烯链段,导致聚丙烯材料的熔点降低,但仍远高于交联聚乙烯的熔点。乙烯链段会参与到聚丙烯的结晶过程中,但不会单独结晶。聚丙烯的断裂伸长率为712%,高于交联聚乙烯的564%,优异的力学性能更有利于电缆的运输和安装施工。90℃下聚丙烯的电气强度为91.5 kV/mm,是相同温度下交联聚乙烯电气强度的123%,并且聚丙烯的电气强度对温度具有更好的稳定性。综合力学性能和电气性能来看,直接合成的聚丙烯性能不逊色于交联聚乙烯,可作为中压电缆的绝缘材料。

Thermoplastic polypropylene material has excellent electrical and thermal properties.It does not require cross-linking and degassing in the production process of power cable insulation,has low energy consumption and good environmental friendliness,and can be recycled compared with cross-linked polyethylene.In this paper,medium-voltage polypropylene cable and cross-linked polyethylene cable insulation were used as the research object.The directly synthesized polypropylene and cross-linked polyethylene were analyzed by differential scanning calorimetry,Fourier infrared spectroscopy,and X-ray diffraction analysis,and their mechanical tensile properties,dielectric constant and loss,breakdown strength,and other macroscopic properties were tested.The results show that the structure of the directly synthesized polypropylene is interspersed with ethylene segments,which leads to the melting temperature of polypropylene material decrease,but its melting temperature is still much higher than that of the cross-linked polyethylene.The ethylene segment will participate in the crystallization process of polypropylene,but will not crystallize alone.The elongation at break of polypropylene is 712%,which is higher than that of the cross-linked polyethylene(566%),which is more conducive to the transportation and installation of cable.The breakdown strength of polypropylene at 90℃ is 91.5 kV/mm,which is 123% higher than that of the cross-linked polyethylene at the same temperature,and the breakdown strength of polypropylene has better stability with respect to temperature.In terms of comprehensive mechanical properties and electrical properties,the performance of directly synthesized polypropylene is not inferior to cross-linked polyethylene,which can be used as an insulating material for medium voltage cables.