Precipitated silica (white carbon black) is an inorganic filler widely used in silicone rubber, coatings, plastics, and electronic materials. However, the surface of untreated silica contains a large number of hydroxyl groups, making it prone to moisture absorption and agglomeration, which impairs its dispersion performance.

Hexamethyldisilazane (HMDS) is a highly effective surface modifier. It reacts chemically with the hydroxyl groups on the silica surface, transforming it from hydrophilic to hydrophobic and thereby significantly enhancing the filler's properties.

HMDS treatment markedly reduces the silica's moisture absorption while improving its flowability and dispersibility. In silicone rubber systems, the modified silica disperses more uniformly within the matrix, boosting the product's mechanical strength, wear resistance, and processing stability.

Furthermore, HMDS treatment helps minimize equipment fouling and dust generation, leading to increased production efficiency. Consequently, HMDS has become a key choice for the hydrophobic treatment of silica in applications such as high-performance silicone rubber, sealants, and electronic packaging materials.