紫外辐射加速老化高温硫化硅橡胶的X射线光电子能谱研究

Study on X-Ray Photoelectron Spectroscopy of High-Temperature Vulcanized Silicone Rubber Accelerated Aging by Ultraviolet Radiation

高温硫化硅橡胶具有优良的电气性能、机械性能、憎水性而广泛应用于特高压输电线路,但亦会受外界环境的影响而老化,其抗紫外老化性能受到关注。课题组模拟户外紫外辐射环境,设计搭建了可调式紫外辐射加速老化试验箱,对A、B两个厂家的高温硫化硅橡胶样品进行了紫外辐射(0,500和1000 h)加速老化实验,重点对辐射前后的试样进行X射线光电子能谱全谱扫描和窄区谱分析、确定元素化学位移及相对含量,分析紫外辐射对高温硫化硅橡胶表面化学态的影响,进而判断紫外辐射加速高温硫化硅橡胶老化机制。结果表明:高温硫化硅橡胶主要元素为O_(1S),C_(1S),Si 2p,其中O_(1S)主要以O—Si—O(532.4 eV)的形式存在,紫外辐射后,拟合分峰观察到534 eV的—OH的小峰,积分面积随辐照时间延长而增加;C_(1S)为C—H,C—C(284.8 eV)或C—O(286.3 eV),随着辐射时间的延长,C—H和C—C结合能峰积分面积减小,C—O结合能峰的积分面积略微增加;Si_(2p)为Si—C(102.39 eV),紫外辐射后新增SiO_(x)(x=3~4)结合能峰(103.6 eV)且积分面积随辐射时间延长而增加。分析认为紫外辐射加速老化的机理是紫外线切断硅橡胶中键能较低的部分Si—C,C—C和C—H键,裂解后的自由基可相互结合发生交联反应形成SiO_(x)(x=3~4);辐射产生高活性的臭氧氧化自由基生成—COOH。XPS技术能够探究高温硫化硅橡胶的表面化学态从而促进其老化机理的研究。

High temperature vulcanized(HTV)silicone rubber composite insulators are widely used in UHV transmission lines,and its ultraviolet aging resistance has been paid more and more attention.In this paper,the samples of high temperature vulcanized silicone rubber come from two manufacturers,X-ray full spectrum scanning and narrow zone spectrum analysis were carried out on the radiated samples to analyze the influence of ultraviolet radiation on the surface chemical properties of high temperature vulcanized silicone rubber,and then to determine the aging mechanism of high temperature vulcanized silicone rubber.The results are as follows:the main elements of high temperature vulcanized silicone rubber are O,C and Si,among which O_(1S) mainly exist in the form of O—Si—O(532.4 eV).After ultraviolet radiation,the COOH peak of 534 eV was increased,and the integral area increased with the extension of irradiation time.C_(1S) was C—H,C—C(284.8 eV)or C—O(286.3 eV).With the extension of rad iation time,the integral area of C—H and C—C binding energy peak decreased,while that of C—O binding energy peak increased slightly.Si_(2p) was Si—C(102.39 eV),the binding energy peak of SiO_(x)(x=3~4)was increased aft er ultraviolet radiation(103.6 eV),and the integral area increased with the extension of radiation time.The mechanism of accelerated aging caused by UV radiation is that part of Si—C and C—C bonds with a low bond energy of silicone rubber are cut off by ultraviolet radiation.After cleavage,free radicals can combine with each other and cross-link to form SiO_(x)(x=3~4);Free radicals are oxidized by ozone to COOH.X-ray photoelectron spectroscopy(XPS)plays an important role in the study of aging mechanism of high temperature vulcanized silicone rubber.