Electrical and Environmental Aging of Silicone Rubber

本文对SIR的老化和憎水性恢复进行了实验室研究。紫外线辐射，电晕放电，酸雨，干带电弧作为老化的来源。化学和形态分析用于检测来自这些应力的表面化学和结构变化。高度移动的低分子量（LMW）链的性质实现了快速恢复的疏水性仔细检查。研究了应力引起的SIR的产生和消失，发现应力和环境应力引起的SIR的疏水迁移是研究SIR老化和寿命的线索。紫外线辐射，电晕放电和干带电弧老化过程中的作用是明确的。结果表明，氧化反应是导致PDMS交联、支化、交换的主要化学反应。此外，高移动的LMW链（4至6个碳原子的环状硅氧烷低聚物）可用于制备高分子量聚硅氧烷。 ...更多信息 分子单元）在重新获得因电和环境应力而暂时丧失的疏水性方面起着重要作用。然而，随着氧化的发展，形成硅烷醇基团，其是氧化的副产物，并且它们阻止高度移动的LMVV链迁移到亲水层上。此外，高移动的LMW链由于交联和它们的蒸发而减少。当回收SIR时，应发生上述化学反应。然而，在这种情况下，ESCA能够分析非常浅的材料表面层（<10 nm）将是无用的，因为移动的LMW链隐藏了老化的表面。采用高加速电压的EDX能很方便地深入样品（小于1 μm）。橡胶中环状硅氧烷低聚物的量也是预测寿命的重要信息。从所有的信息，他们的老化到现在，这项研究可以得出一个典型的情况下，所有的生活SIR用于户外高压绝缘。提出的方案将通过未来的现场老化试验结果进行验证。少

This is a laboratory study on the aging of SIR and hydrophobicity recovery. UV radiation, corona discharges, acid rain, dry-band arcing are employed as sources of the aging. Chemical and morphological analysis is used to detect the surface chemical and structural changes derived from these stresses. The nature of highly mobile low molecular weight (LMW) chains achieving a quick recovery of the hydrophobicity is carefully examined. Their generation and extinction caused by these stresses are investigated.It is found that hydrophobic transfers of SIR resulting from electrical and environmental stresses are investigated as a clue to draw their aging scenarios and estimate their lifetimes. Roles of UV radiation, corona discharges and dry-band arcing during the aging is clearly identified. It is shown that oxidation that induces crosslinking, branching, interchanging in PDMS are the most dominant chemical reactions. Furthermore, highly mobile LMW chains (cyclic silicone oligomers of 4 to 6 … More molecular units) play a significant role to regain the hydrophobicity temporarily lost by electrical and environmental stresses. However, with the development of oxidation, silanol groups are formed, which are byproducts of oxidation, and they prevent highly mobile LMVV chains from migrating onto hydrophilic layers. Moreover, highly mobile LMW chains decrease due to crosslinking and their evaporation. When the recovery of SIR worsens, the above chemical reactions should take place. Hence, the atomic presence of oxygen at the surface can be a helpful indication to determine the aging level of SIR.However, in this case, ESCA able to analyze very shallow layer of material surfaces (<10 nm) would not be useful because mobile LMW chains hide the aged surfaces. EDX with high accelerating voltage to penetrate deeply into the sample (mere than 1 μm) would be convenient. The amount of cyclic silicone oligomers in the rubber is also significant information to predict the lifetimes. From all the information regarding their aging up to now, this study could draw a typical scenario of all lives of SIR used for outdoor HV insulation. This scenario proposed will be verified by the future test results of field aging. Less