功能化SiO_(2)/UV-XLPE纳米复合材料的交流介电性能研究

AC dielectric properties of functionalized SiO_(2)/UV-XLPE nanocomposites

针对纳米SiO_(2)材料在XLPE基体中容易团聚的问题,采用巯基-双键点击化学原理和纳米材料的表面改性技术,将纳米SiO_(2)引入到了紫外光交联聚乙烯的网状结构中,提高了纳米SiO_(2)在XLPE基体中的分散性。同时引入了更多的深陷阱,改变了功能化纳米SiO_(2)与XLPE基体之间的界面特性,从而提高了功能化SiO_(2)/UV-XLPE纳米复合材料的介电性能。对材料进行核磁共振氢谱、红外光谱以及扫描电镜等实验进行结构表征。在线性升温条件下测试材料在工频下的介电常数ε_(r)和损耗角正切值tanδ,探讨功能化纳米SiO_(2)的表面高介电壳层对纳米复合材料的变温介电特性的影响;通过TSC测试探究材料内部的陷阱能级分布情况,并在不同温度下测试了材料的交流击穿特性。随着温度的提高,复合材料内部杂质分子热运动加剧,使得相对介电常数ε_(r)随温度提高减小,而偶极子转向在介电损耗中的贡献逐渐增大,所以损耗角正切值tanδ呈现出变大的趋势。另外功能化纳米SiO_(2)在界面中引入了许多俘获电子的深陷阱,这些深陷阱限制了载流子的迁移,使得高温交流击穿强度有了显著提高,其中1.5wt%TMPTA-s-SiO_(2)交流击穿场强最高,80℃时相对于纯XLPE的特征击穿场强要高出5.8%,在高温下具有最优良的耐击穿稳定性。

Aiming at the problem that nano-SiO_(2) materials are easy to agglomerate in XLPE matrix,nano-SiO_(2) was introduced into the network structure of UV-XLPE by using sulfhydryl double bond click chemistry and surface modification technology of nano materials,which improves the dispersion of nano-SiO_(2) in XLPE matrix and introduces more deep traps;The polar groups on the surface of functionalized nano-SiO_(2) also change the interface characteristics between it and XLPE matrix,so as to improve the dielectric properties of functionalized SiO_(2)/UV-XLPE nanocomposites.The structure of the material was characterized by 1 H NMR,FTIR and SEM.The dielectric constant of the material at power frequency was measured under the condition of ε_(r) and tanδ.The effect of high dielectric shell on the temperature dependent dielectric properties of functional nano-SiO_(2) was discussed.The distribution of trap energy levels in the material was explored by TSC test,and the AC breakdown characteristics of the material were tested under a certain temperature gradient.With the increase of temperature,the thermal motion of impurity molecules in the composites intensifies,making the relative dielectric constant ε_(r) decreases with the increase of temperature,and the contribution of dipole steering to dielectric loss increases gradually,so the tangent of loss angle tanδshowing a growing trend.In addition,the functionalized nano-SiO_(2) introduces many deep traps that capture electrons in the interface.These deep traps limit the migration of carriers and significantly improve the high-temperature AC breakdown strength.Among them,the AC breakdown field strength of 1.5wt%TMPTA-s-SiO_(2) is the highest,and the characteristic breakdown field strength is 5.8%higher than that of pure XLPE at 80℃,with the best breakdown resistance stability at high temperature.