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. 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. To achieve this, the help of the reinforcing agent must not be reduced.

　　The reinforcing agent is an important kind of rubber additive, which mainly plays the reinforcing role of rubber mechanical properties and aging resistance. Precipitated white carbon black is one of its representatives. White is usually a white powder or granular, non-toxic, the specific surface area is large, the property is stable, and it has the characteristics of high dispersibility, good electrical insulation, high-temperature resistance, insoluble in common acids, etc.

　　Generally speaking, the reinforcing effect of precipitated white carbon black is enhanced due to small particle size and large specific surface area. Since sizing materials molecular chain usually exists in an irregular state, showing high tensile force and tear resistance, when the reinforcing agent is mixed into sizing materials, sizing materials of molecular chain is attached to the surface of the reinforcing agent, to arrange the particles neatly, some elongation is lost. Precipitated silica has a large specific surface area and surface activity, so it can make the molecular chain of rubber adhere effectively and achieve the maximum reinforcing effect.

　　However, although the precipitated white carbon black is good, it cannot be used directly. The synthesis process of precipitated white carbon black is essentially the process of converting dense crystal type quartz sand into loose amorphous hydrated silica, namely, SiO_2 →sio_2 · nH2O, finally, the surface of the precipitated white carbon black will contain a large number of Silicon hydroxyl groups, which have high activity, making the surface of white carbon black appear hydrophilic, poor dispersibility, easy to agglomerate among particles and other phenomena, it affects its application in the polymer matrix. Therefore, to broaden the application field, hydrophobic modification of white carbon black is needed to reduce the content of silicon hydroxyl and enhance its dispersibility in organic materials.