纳米掺杂对环氧复合绝缘材料不均匀热老化特性的影响  

Effect of nano-doping on inhomogeneous thermal ageing characteristics of epoxy composite insulating material

作　　者：任志刚 潘泽华 郭卫 陈平 及洪泉 REN Zhigang;PAN Zehua;GUO Wei;CHEN Ping;JI Hongquan(State Grid Beijing Electric Power Research Institute,Beijing 100075,China)

机构地区：[1]国网北京市电力公司电力科学研究院,北京100075

出　　处：《绝缘材料》2023年第12期92-97,共6页Insulating Materials

摘　　要：本文制备了改性纳米氧化铝掺杂质量分数分别为0%、1%、10%的环氧复合绝缘材料,对其在150℃下开展了热老化试验,并通过动态机械(DMA)测试、扫描电子显微镜(SEM)测试和线性热膨胀测试研究其热老化特性及机理。结果表明:环氧复合绝缘材料在热老化过程中形成了不均匀的老化结构,且表面老化层厚度与纳米氧化铝的含量有关。当纳米氧化铝掺杂质量分数为1%时,试样的表面老化层厚度最小,此时纳米颗粒分散性良好且紧密地镶嵌在环氧基体中。结合玻璃化转变的自由体积理论,计算发现纳米氧化铝掺杂质量分数为1%时,试样的自由体积分数最小,且对应的环氧基体α主松弛时间最长,分子链活动性最低。在环氧树脂中加入适量改性纳米氧化铝可以提高分子链的交联程度,降低体系的自由体积,进而削弱氧气在材料内部的扩散能力,最终降低环氧复合绝缘材料的不均匀热老化程度。Epoxy composite insulating materials doped with 0%,1%,and 10% of modified nano Al_(2)O_(3) were prepared and conducted thermal ageing tests at 150℃,and their thermal ageing characteristics and mechanism were studied through dynamic thermal mechanical testing,scanning electron microscopy testing,and linear thermal expansion testing.The results show that an inhomogeneous ageing structure is formed in epoxy composite insulating material during thermal ageing,and the thickness of surface ageing layer is related to the content of nano Al_(2)O_(3).When the doping mass fraction of nano Al_(2)O_(3) is 1%,the thickness of surface ageing layer is the smallest,and the nanoparticles are well dispersed and closely embedded in the epoxy matrix.According to the free volume theory of glass transition,it is found that the free volume fraction of sample is the smallest when the doping mass fraction is 1%,the corresponding α main relaxation time of the epoxy matrix is the longest,and the molecular chain activity is the lowest.Adding an appropriate amount of modified nano Al_(2)O_(3) into the epoxy resin can improve the cross-linking degree of molecular chain and reduce the free volume of system.Thereby the diffusion of oxygen in the material is weakened,and finally the inhomogeneous thermal ageing degree of the epoxy composite insulating material is reduced.

关 键 词：纳米氧化铝 环氧树脂 热老化 自由体积 

分 类 号：TM215[一般工业技术—材料科学与工程]