As an excellent white reinforcing agent in rubber industry, Silica can significantly improve the performance of rubber. Its reinforcement mechanism mainly involves the following aspects:

1. Physical adsorption and chemical bonding

Physical adsorption:

Silica particles are amorphous and crystallized in disorder. When their surface contacts with rubber macromolecules, physical adsorption will occur. This adsorption enables Silica particles to adhere tightly to the rubber molecular chain, thereby enhancing the mechanical properties of rubber.

Chemical bonding:

There are active groups such as siloxy, isolated hydroxyl, and hydrogen chain connection on the surface of Silica, especially the Si-O bond in the center of its structure is polar and can produce strong binding ability. This makes the surface activity of Silica particles large and can form a strong chemical bond with the rubber molecular chain. This chemical bonding further enhances the reinforcing effect of Silica on rubber.

2. Hydrogen bond and spatial network structure

Hydrogen bond formation:

The active hydroxyl groups on the surface of Silica can form hydrogen bonds with hydrogen atoms on the rubber macromolecule chain. The presence of hydrogen bonds makes the interaction between silica and rubber molecules closer, thereby improving the strength and toughness of rubber.

Spatial network structure:

The interaction between silica particles and the bridge chain between silica-polymer-silica constitute a spatial network structure. This structure enables the rubber molecular chain to better disperse stress when subjected to external forces, thereby improving the tear resistance and wear resistance of rubber.

3. Effect of particle size and specific surface area

Particle size:

The smaller the particle size of silica, the larger the specific surface area, the larger the contact surface with rubber, and therefore the better the reinforcement effect on rubber. Generally speaking, nano-sized silica has the most significant reinforcement effect on rubber.

Specific surface area:

Silica with a large specific surface area can provide more active sites to interact with rubber molecular chains, thereby enhancing the mechanical properties of rubber.

4. Surface properties and dispersibility

Surface properties:

The active groups such as hydroxyl groups on the surface of silica not only affect its interaction with rubber molecules, but also affect its dispersibility in water. Hydrophilic silica has poor dispersibility in rubber, and needs to be modified to improve its hydrophobicity and dispersibility.

Dispersibility:

Silica with good dispersibility can be more evenly distributed in the rubber matrix, so as to give full play to its reinforcing effect. Therefore, in practical applications, coupling agents, dispersants and other additives are often used to improve the dispersibility of silica in rubber.

5. Precautions in practical applications

Vulcanization speed:

The pH value of silica will affect the vulcanization speed of rubber. Therefore, it is necessary to understand the pH value of silica before use and make corresponding adjustments to ensure that the vulcanization speed is moderate.

Mixing conditions:

During the mixing process, it is necessary to pay attention to controlling the mixing temperature and time to avoid agglomeration of silica or destruction of its structure. At the same time, it is also necessary to pay attention to the selection of other components in the formula to give full play to the reinforcing effect of silica.

In summary, the reinforcement mechanism of silica in the rubber industry involves physical adsorption, chemical bonding, hydrogen bonding and spatial network structure, the influence of particle size and specific surface area, and surface properties and dispersibility. In practical applications, these factors need to be considered comprehensively to give full play to the reinforcing effect of silica and improve the performance of rubber.