硅橡胶复合绝缘子在架空输电线路上运行时会发生绝缘子温度升高和环氧芯棒腐蚀断裂的故障。为了了解和解释这两类故障发生的原因，本文针对高温硫化硅橡胶的吸水性、吸湿性和透水性、透湿性，以及水、湿气对硅橡胶和芯棒-护套界面性能的影响机理进行了理论分析和实验研究。制备了不同无机填料特性的多种硅橡胶样品；揭示了无机填料特性、溶液种类、溶液浓度、温度、拉应变和交流电场对硅橡胶吸水性的影响规律，以及无机填料特性、拉应变、温度、湿度和交流电场对硅橡胶吸湿性的影响规律；分析了吸水、吸湿后的硅橡胶在干燥环境中的脱水性、脱湿性；利用正电子湮没技术研究了硅橡胶的自由体积特性，通过比较吸水前、后的自由体积特性阐释了硅橡胶的吸水机理，得出了吸水的本质原因：吸水在于其内存在自由体积，吸收的水会储存在自由体积内；并从自由体积的角度解释了硅橡胶单位体积饱和吸水量随填料含量的变化规律。通过研制硅橡胶透水量和透湿量的测量装置，研究了硅橡胶的透水性和透湿性，获得了无机填料特性、溶液种类、溶液浓度、温度和厚度对硅橡胶透水量的影响规律，以及无机填料特性、湿度和厚度对硅橡胶透湿量的影响规律；通过分析水分子在硅橡胶内的扩散规律，得出了透水、透湿时水分子在硅橡胶内的渗透时间与其厚度之间的半定量关系表达式。揭示了水、溶液和湿气对硅橡胶体积电阻率、相对介电常数、介质损耗角正切值、工频击穿场强、吸收电流和极化电荷等电气性能的影响规律；并通过“水壳”模型阐释了硅橡胶吸水、吸湿后极化现象增强的微观机理；通过活化能的计算揭示了水和溶液浸渍对硅橡胶热稳定性的影响规律；通过表面硅氧烷含量的测量及表面微观形貌的观察阐释了水和溶液浸渍对硅橡胶憎水性的影响机制，实验证实了微观形貌改变导致的表面粗糙度增加提高了硅橡胶的憎水性。最后研究了芯棒-护套界面有水或湿气时的性能，通过水扩散泄漏电流实验研究了硅烷偶联剂的涂覆次数对芯棒-护套界面耐水侵害能力的影响，提出了基于芯棒与护套径向粘结力测量的评价界面强度及其耐水侵害能力的定量方法，初步探讨了界面未偶联或硅烷偶联剂脱落现象的检验方法，且通过复合绝缘子泄漏电流的研究证实了水确实能直接透过护套进入该初始界面缺陷内。

Two operation troubles including the temperature rise of the insulator and the decay-like fracture of the epoxy resin core have occurred in the outdoor silicone rubber composite insulators on overhead transmission lines. In order to get knowledges of and explain the inducement reasons of these two troubles, the theoretical analyses and experimental researches on water and moisture absorptivity and water and moisture permeability of high-temperature vulcanized silicone rubber and the influences of water and moisture on the properties of the silicone rubber and the core-sheath interface are conducted in this thesis.The silicone rubber samples with various inorganic filler characteristics were prepared. The influence laws of inorganic filler characteristics, kind and concentration of aqueous solutions, temperature, mechanical tensile strain and alternating electric field on the water absorptivity of silicone rubber and those of inorganic filler characteristics, mechanical tensile strain, temperature, humidity and alternating electric field on its moisture absorptivity were revealed. Also, the dehydration and dehumidification properties in dry environment of the silicone rubber after water and moisture absorption were preliminarily analyzed. The free volume characteristic of silicone rubber was researched using Positron Annihilation Technique. And the water absorbing mechanism of silicone rubber, as a fundamental issue, was interpreted by comparing the free volume characteristic of silicone rubber before and after water absorption, and the essential reason of water absorption that water absorption is owing to the free volume in silicone rubber and absorpted water will store in the free volume was obtained. The variation law of the saturated water absorption per unit volume of silicone rubber with filler content was explained from the point of free volume.The influence laws of filler characteristics, kind and concentration of aqueous solutions, temperature and sample thickness on the water permeation flux of silicone rubber and those of filler characteristics, humidity and sample thickness on its moisture permeation flux were obtained by developing the experimental facility used to measure the water and moisture permeation flux and studying water and moisture permeability of silicone rubber. The semiquantitative relational expression between the penetration time of water molecule in silicone rubber at water and moisture permeation and its thickness was given by analyzing the diffusion rule of water molecule in silicone rubber.The influence laws of water and aqueous solutions and moisture on the electrical performances of silicone rubber including volume resistivity, relative dielectric constant, tanδ, power frequency breakdown strength, absorption current and polarization charge were revealed. And the micromechanism of the polarization strengthening of silicone rubber after water and moisture absorption was explained using “water shell” model. The influence law of water and solutions immersion on the thermostability of silicone rubber was revealed by studying the activation energy. The influencing mechanism of water and solutions immersion on the hydrophobicity of silicone rubber was explained by studing the surface siloxane content and surface microtopography of silicone rubber, and the surface roughness increase due to surface microtopography change improved the hydrophobicity of silicone rubber.The properties of the core-sheath interface at the water and moisture environment were finally researched. The influence of the coating times of the silane coupling agent on the water resistant ability of the core-sheath interface was investigated by water diffusion leakage current experiment. The quantitative evaluation method of the interfacial strength and its water resistant ability based on the measurement of the radial adhesion stress of the core-sheath was put forward. The method used to detect the initial interface defects (no adhesion or de-adhesion of silane coupling agent at the interface) was preliminary discussed. The phenomenon that water can indeed directly permeate through the sheath into the initial interface defects was confirmed by studying the leakage current of composite insulator.