Precipitated silica should be used well, and surface modification is indispensable Rubber products are very common in people's lives, and the demand is gradually expanding with the development of the national economy. In order to prolong the service life of these rubber products, it is necessary to enhance their aging resistance, wear resistance, high and low temperature resistance, acid and alkali resistance, insulation and other properties.


Reinforcing agent is an important type of rubber auxiliaries. It mainly plays the role of reinforcing the mechanical properties and aging resistance of rubber. Precipitated silica is one of its representatives. White is usually white powder or granule, non-toxic. , Large specific surface area, stable properties, high dispersion, good electrical insulation, high temperature resistance, insoluble in common acids and so on.


Generally speaking, the reinforcing effect of precipitated silica is enhanced by the small particle size and large specific surface area. Since the molecular chain of the rubber compound usually exists in an irregular state, showing high tensile force and tear resistance, when the reinforcing agent is mixed into the rubber compound, the molecular chain of the rubber compound is attached to the surface of the reinforcing agent, in order to make the particles become Neatly arranged and loses some elongation. Precipitated silica has a large specific surface area and surface activity, so it can effectively attach the molecular chain of the rubber to achieve the maximum reinforcement effect.


However, although precipitated silica is good, it cannot be used directly. The synthesis process of precipitated silica is essentially the process of converting dense crystalline quartz sand into loose amorphous hydrated silica, that is, SiO2→SiO2·nH2O. The surface of the resulting precipitated silica will contain a large amount of silicon. Hydroxyl groups, these silyl hydroxyl groups have high activity, which makes the surface of silica appear hydrophilic, poor in dispersibility, and prone to agglomeration between particles, which affects its application in polymer matrices. Therefore, in order to broaden the application field, it is necessary to hydrophobically modify silica to reduce the silanol content and enhance its dispersibility in organic materials.