伽玛线辐射对LDPE表面电导率的影响.docVIP

  伽玛线辐射对 LDPE 表面电导率的影响# 高宇，门业堃，杜伯学* （天津大学电气与自动化工程学院，天津 300072） 5 10 15 20 25 30 35 40 摘要：应用于核电站、宇宙航天器等辐射环境中的聚乙烯绝缘材料因表面电荷积聚而易于引 发放电事故，掌握高能辐射对聚乙烯表面电导率的影响规律对抑制表面电荷积聚、保障核设 施绝缘安全具有重要意义。选取厚 2 mm 的低密度聚乙烯薄板为试样，采用 60Co 伽玛射线 源以 10 kGy/h 的辐射率对其进行辐射，总辐射量分别为 100 kGy 和 1000 kGy。基于三电极 法测量不同相对湿度下试样的表面电导率，结合衰减全反射傅立叶变换红外光谱和凝胶含 量，分析总辐射量的影响。结果表明：表面电导率随总辐射量的增加而增大；随相对湿度从 45%增大至 75%，表面电导率增大约 5 个数量级。论文认为，伽玛线辐射引发的氧化反应使 低密度聚乙烯表层形成羰基，可作为浅能级载流子陷阱或吸附水分子，促进电荷迁移，从而 导致表面电导率提高。 关键词：绝缘技术；低密度聚乙烯；表面电导率；伽玛线辐射；衰减全反射傅立叶变换红外 光谱；凝胶含量 中图分类号：TM852 Effect of gamma-ray irradiation on surface conductivity of LDPE GAO Yu, MEN Yekun, DU Boxue (School of Electrical Engineering and Automation, Tianjin University,Tianjin 300072) Abstract: In this work, the effect of gamma-ray irradiation on surface conductivity of LDPE has been investigated. The sample was previously irradiated at room temperature in air to 100 kGy and then to 1000 kGy with a dose rate of 10 kGy / h by using a 60Co gamma-source. Surface conductivity was measured by means of an insulation resistance meter (Model PC 68) at various relative humidity. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectrum and gel fraction were utilized to estimate the change in molecular structure of LDPE. Obtained results show that the surface conductivity tends to increase with the growth of the total dose. An increase in the relative humidity from 45% to 75% leads to the enhancement of surface conductivity from the order of 10-17 S to 10-12 S. It is suggested that the surface conductivity is mainly dependent upon the gamma-ray irradiation induced oxidation in surface layer of the material. Key words: insulation technology; low density polyethylene; surface conductivity; gamma-ray irradiation; ATR-FTIR; gel fraction 0 引言 聚乙烯(Polyethylene, PE)绝缘材料广泛应用于核电站、宇宙航天器等辐射环境下的电气 电子设备中[1]。受到电子束、伽玛线等高能辐射的作用，PE 发生电离、激发并引发断键、 氧化、交联等物理、化学变化，导致其分子结构改变，影响材料的绝缘性能[2]。K. H. Stark 等人采用能量为 4 MeV 的电子束对 PE 进行辐射，发现总辐射量 2000 kGy 时 PE 的击穿场 强为总辐射量 1500 kGy 时的 2 倍[3]。G.