1. Chemical structure of silica
The composition of 95~99% of silica is SiO2. It has been confirmed by X-ray diffraction that the structure of silica is different due to the different preparation methods of silica. The internal structure of fumed silica is almost completely a three-dimensional network structure of silicic acid that is closely arranged. This structure makes the particles less hygroscopic, strong surface adsorption, and strong reinforcement. In the structure of precipitated silica, in addition to silicic acid with a three-dimensional structure, there are still more silicic acid with a two-dimensional structure, resulting in a loose structure and many capillary structures, which are easy to absorb moisture, thus reducing its reinforcement. active.

2. The structure of silica
The structure of silica is like carbon black, and its basic particles are spherical. During the production process, these elementary particles collide with each other at high temperature to form a branch-like structure linked by chemical bonds, which is called elementary aggregates. The chain-like structures are adsorbed by hydrogen bonds to form a secondary aggregate structure, which is easily destroyed during processing and kneading.