The term “structuring” used in silicone rubber describes a phenomenon of the increase in the viscosity of polydimethylsiloxane filled with silica during storage, which limits the applications of the room temperature vulcanized (RTV) silicone rubber in the field of aerospace and military. In this pursuit, the present study was envisaged to solve the problem of structuring of the RTV. A solvent-free method was used to hydrophobize the hydrophilic silica with hexamethyldisilazane. An RTV composition prepared using eight parts of hydrophobic silica with 2.91% C content exhibited a viscosity of less than 100 Pa s, with no significant change in 21 days. In contrast, eight parts of the hydrophilic fumed silica showed an initial viscosity of RTV to be greater than 2,000 Pa s. Silica samples with different adsorbed water content were used to prepare the RTV compositions. It was found that the viscosity of the RTV prepared using the sufficiently dried silica was 5.6 times lower than that of the wet silica. The “dissolution” model of the silica–silica hydrogen bonds in water was proposed. Furthermore, the change in the viscosity of the RTV compositions at different temperatures in the range of −15°C to 30°C was studied. The viscosity of RTV stored at –15°C for 34 days did not change significantly, whereas that stored at room temperature increased from 100 to 1,710 Pa s within 21 days.

中文翻译：

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气相法二氧化硅填充的端羟基聚二甲基硅氧烷的结构

硅橡胶中使用的术语“结构化”描述了在存储过程中填充有二氧化硅的聚二甲基硅氧烷的粘度增加的现象，这限制了室温硫化（RTV）硅橡胶在航空航天和军事领域的应用。在这种追求下，设想了本研究来解决RTV的结构化问题。使用无溶剂方法用六甲基二硅氮烷疏水化亲水性二氧化硅。使用八份具有2.91％C含量的疏水性二氧化硅制备的RTV组合物的粘度小于100 Pa s，在21天内没有明显变化。相反，八份亲水性气相二氧化硅显示的RTV初始粘度大于2,000 Pa s。使用具有不同吸附水含量的二氧化硅样品来制备RTV组合物。发现使用充分干燥的二氧化硅制备的RTV的粘度比湿二氧化硅的粘度低5.6倍。提出了二氧化硅-二氧化硅氢键在水中的“溶解”模型。此外，研究了RTV组合物在-15℃至30℃范围内的不同温度下的粘度变化。在–15°C下保存34天的RTV的粘度没有明显变化，而在室温下保存的RTV的粘度在21天内从100 Pa升至1,710 Pa s。此外，研究了RTV组合物在-15℃至30℃范围内的不同温度下的粘度变化。在–15°C下保存34天的RTV的粘度没有明显变化，而在室温下保存的RTV的粘度在21天内从100 Pa升至1,710 Pa s。此外，研究了RTV组合物在-15℃至30℃范围内的不同温度下的粘度变化。在–15°C下保存34天的RTV的粘度没有明显变化，而在室温下保存的RTV的粘度在21天内从100 Pa升至1,710 Pa s。