Abstract We have recently shown [1,2] that one component room temperature vulcanized (RTV-1) silicone rubbers (SIR) based on polydimethylsiloxane (PDMS) can be rapidly degraded by low voltage (LV) energized aqueous salt solutions by previously unreported aging mechanisms related to the formation of hypochlorous acid in high voltage (HV) transmission line applications. In this study, we are showing how to improve the resistance of the rubbers to extreme environmental aging by embedding TiO2 micro-particles. Molecular dynamics (MD) simulations were conducted to determine the combined effect of TiO2 and different concentrations of hydrophobic PDMS methyl groups on surface hydrophobicity of a TiO2/PDMS composite. In addition, the effects of both TiO2 and silica on the diffusivities of LV aqueous salt components in the PDMS were predicted and related to unique interfacial interactions between the particles and the methyl groups of the PDMS. Rutile TiO2 reoriented methyl groups away from the particles reducing the diffusivities of water and hypochlorous acid. This effect shielded the PDMS network against environmental chain scissions. On the other hand, silica attracted the groups accelerating acid and water migrations and thus enhancing damage to the network. In the experimental part, TiO2/RTV was subjected independently to hypochlorous acid and electrolyzed LV aqueous salt. As expected, TiO2 greatly increased the contact angle, reduced the surface energy and improved the hydrophobicity of the composite, mitigating the negative effect of the reduced concentrations of methyl groups. As a result, aging damage to the rubber was dramatically reduced by about 50% in highly oxidative environments.

中文翻译：

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耐老化TiO 2 /硅橡胶复合材料

摘要 我们最近表明 [1,2] 基于聚二甲基硅氧烷 (PDMS) 的一种组分室温硫化 (RTV-1) 硅橡胶 (SIR) 可以通过低压 (LV) 赋能的盐水溶液快速降解高压 (HV) 输电线路应用中次氯酸形成的相关机制。在这项研究中，我们展示了如何通过嵌入 TiO2 微粒来提高橡胶对极端环境老化的抵抗力。进行分子动力学 (MD) 模拟以确定 TiO2 和不同浓度的疏水性 PDMS 甲基对 TiO2/PDMS 复合材料的表面疏水性的综合影响。此外，预测了二氧化钛和二氧化硅对 PDMS 中 LV 盐水溶液组分扩散率的影响，并与颗粒和 PDMS 甲基之间独特的界面相互作用有关。金红石 TiO2 使甲基远离颗粒，从而降低了水和次氯酸的扩散率。这种效应使 PDMS 网络免受环境断链的影响。另一方面，二氧化硅吸引了加速酸和水迁移的基团，从而增强了对网络的破坏。在实验部分，TiO2/RTV 独立地经受次氯酸和电解的 LV 水盐。正如预期的那样，TiO2 大大增加了接触角，降低了表面能并提高了复合材料的疏水性，减轻甲基基团浓度降低的负面影响。结果，在高度氧化的环境中，橡胶的老化损坏显着降低了约 50%。