Types and characteristics of silicon dioxide

The reinforcing filler for silicone rubber mainly refers to synthetic silicon dioxide, also known as silicon dioxide. Silica is divided into fumed silica and precipitated silica.

The size, specific surface area, surface properties and structure of fumed silica particles are related to the proportion of feed gas, combustion speed, residence time in the combustion chamber and other factors.

The finer the fumed silica particles are, the larger their specific surface area is, and the better the enhancement effect is, but the worse the operating performance is. On the contrary, the thicker the particles are, the smaller the specific surface area is, so the reinforcement effect is poor, but the operability is good.

Fumed silica is one of the commonly used reinforcing agents for silicone rubber. The rubber compound reinforced by it has high mechanical strength and good electrical properties. The fumed silica can also be used together with other reinforcing agents or weak reinforcing agents to prepare rubber materials with different use requirements.

Precipitated silica The properties of precipitated silica are affected by precipitation conditions, such as acidity, temperature, etc.

Compared with fumed silica reinforced silicone rubber, precipitated silica reinforced silicone rubber has lower mechanical strength and poor dielectric properties, especially after being affected by moisture, but has better thermal aging performance and lower cost. When the mechanical strength of the product is not required, precipitated silica can be used or mixed with fumed silica.

Silica can be treated with appropriate compounds to produce surface hydrophobic substances. The treatment methods mainly include liquid phase method and gas phase method. The conditions of the liquid phase method are easy to control, the product quality is stable, and the treatment effect is good, but the process is complex, and the solvent needs to be recovered; The gas phase process is simple, but the product quality is not stable enough and the treatment effect is poor.