Types and characteristics of silica

The reinforcing filler used in silicone rubber mainly refers to synthetic silica, also known as white carbon black. White carbon black is divided into gas phase white carbon black and precipitated white carbon black.

a, fumed silica

The size, specific surface area, surface properties, structure, etc. of silica particles are related to factors such as the ratio of raw material gas, combustion speed, and residence time of SiO2 nuclei in the combustion chamber.

The finer the gas-phase white carbon black particles, the larger its specific surface area, the better the reinforcing effect, but the worse the operational performance. On the contrary, its particles are thicker and the specific surface area is smaller, the reinforcement effect is poor, but the operability is better.

Fumed silica is one of the most commonly used reinforcing agents for silicone rubber. The rubber compound reinforced by it has high mechanical strength and good electrical properties. Fumed white carbon black can be used together with other reinforcing agents or weak reinforcing agents to prepare rubber compounds with different application requirements.

b. Precipitated silica

The performance of precipitated silica is affected by precipitation conditions such as acidity and temperature.

Compared with the silicone rubber compound reinforced with fumed silica, the rubber compound reinforced with precipitated silica has lower mechanical strength and poor dielectric properties, especially after being damp, but heat-resistant aging The performance is better, and the cost of the rubber compound is much lower. When the mechanical strength of the product is not high, precipitated white carbon black can be used or used together with gas-phase white carbon black.