ISO 18473-3：2018 Fumed silica for silicone rubber application
ISO 23157:2021 was officially published on July 13th, 2021. Guangzhou Huifu Research Institute Co., Ltd., wholly-owned subsidiary of Hubei Huifu, is the leading setting body of this international standard. And this is another international standard project completed by Guangzhou Huifu after ISO 18473-3：2018.
ISO 23157:2021 was registered as PWI at the 10th plenary session in Germany in Oct,2018. Doctor Wang Yuelin, Chairman of Hubei Huifu, is in charge of this project, and Doctor Wu Chunlei as co-director, who is general manager of Guangzhou Huifu Research. With the support of Beijing Physical & Chemical Instrumental Analysis Center and other units, ISO 23157:2021 successfully published after three years’ endeavor.
Fumed silica (pyrogenic silicon dioxide) has a relatively high concentration of silanol groups formed during high-temperature flame hydrolysis and the following cooling process. This specified property enables fumed silica to be widely used as a reinforcing filler, thickener, thixotropy-increasing and anti-sagging additive in numerous industries, for example silicone rubber, coating materials, adhesives and sealants.
The determination of the silanol group content on the surface of fumed silica is essential for both manufacturers and users to develop a high-performance, surface modified fumed silica and improve existing products. Further, it also facilitates the communication among interested parties.
In practice, methods of titration, thermogravimetry (TG), infrared spectroscopy (IR) and reaction gas chromatography can be a choice for the determination of the silanol group content on the surface of fumed silica. Among these methods, the method of reaction gas chromatography is preferred by users due to the advantage of higher sensitivity and better reproducibility.
ISO 23157:2021 is a vital and meaningful supplement to ISO 18473-3：2018. The determination of the silanol group content on the surface of fumed silica is essential for processing properties, mechanical properties, transparency and dielectric properties of silicone rubbers. The release of this method also has a positive impact on the optimization of the overall performance of silicone rubber and the promotion of the development of the silicone rubber industry.
