Silica (silicon dioxide) is a commonly used reinforcing filler in silicone rubber, which can significantly improve the mechanical properties of silica gel, especially the tensile strength. The tensile strength of silica gel can be further improved by optimizing the selection, surface treatment, dispersion process and silica matrix formula of silica. The following are specific improvement strategies:

1. Choose the right type of silica
Specific surface area and particle size: Silica with high specific surface area and small particle size usually has a higher reinforcement effect. For example, fumed silica (specific surface area is usually 100-400 m²/g) has higher activity than precipitated silica, and can more effectively improve the tensile strength of silica gel.
Surface activity: Silica with higher surface activity is more likely to interact with silicone rubber molecular chains, forming a stronger interface bond, thereby improving the reinforcement effect.

2. Surface treatment of silica
Hydrophobic treatment: Surface hydrophobic treatment of silica with silane coupling agent (such as hexamethyldisilazane, vinyltrimethoxysilane, etc.) can reduce the agglomeration between silica particles, improve its dispersibility in silica gel, and enhance the interfacial bonding with silicone rubber.
Graft modification: Grafting functional groups (such as vinyl, epoxy, etc.) on the surface of silica can further improve its compatibility and reactivity with silicone rubber, thereby enhancing the reinforcement effect.

3. Optimizing the dispersion process of silica
High shear mixing: Use high shear mixing equipment (such as internal mixer, double-roll open mill) to evenly disperse silica in the silicone rubber matrix to avoid agglomeration.
Pre-dispersion: Pre-mixing silica with part of silicone rubber or plasticizer to make a masterbatch, and then mixing it with the main rubber material, which helps to improve the dispersibility of silica.

4. Adjust the silicone matrix formula
Increase the molecular weight of silicone rubber: Using a high molecular weight silicone rubber matrix can provide more molecular chain entanglement points, thereby enhancing the interaction between silica and silicone rubber.
Add plasticizer: Adding a proper amount of plasticizers such as low molecular weight silicone oil or phenyl silicone oil can improve the processing performance of silicone rubber, while reducing the friction between silica particles, which helps to improve the tensile strength.
Optimize the vulcanization system: Select appropriate vulcanizers (such as peroxide vulcanizers) and vulcanization aids (such as cross-linking aids, antioxidants, etc.) to ensure that the silicone rubber is fully vulcanized and forms a uniform cross-linked network structure, thereby improving the tensile strength.

5. Control processing conditions
Mixing temperature and time: Appropriate mixing temperature and time can promote the uniform dispersion of silica while avoiding over-vulcanization or degradation of silicone rubber.
Vulcanization temperature and time: Accurately control the vulcanization temperature and time to ensure that the silicone rubber is fully vulcanized and avoid performance degradation caused by insufficient vulcanization or over-vulcanization.

6. Application of nano-silica
Nano-scale silica: Nano-scale silica has a higher specific surface area and smaller particle size, which can more effectively improve the tensile strength of silicone rubber. For example, the particle size of nano-silica is usually in the range of 10-100 nm, which can significantly enhance the mechanical properties of silicone rubber.

7. Composite filler system
Synergy between silica and other fillers: The composite use of silica with other fillers (such as carbon black, calcium carbonate, clay, etc.) can further improve the tensile strength of silicone rubber through the synergistic effect between fillers. For example, the use of silica and a small amount of carbon black can simultaneously improve the tensile strength and wear resistance of silicone rubber.

8. Use of structure control agent
Preventing structuring: Adding structure control agents (such as diphenylsilanediol, hydroxy silicone oil, etc.) to silicone rubber can prevent silica from structuring during storage (i.e., the rubber hardens due to hydrogen bonding between silica particles), thereby maintaining the processing performance and mechanical properties of silicone rubber.

9. Post-treatment process
Heat treatment: Appropriate heat treatment of the vulcanized silicone (such as secondary vulcanization) can further optimize the cross-linked network structure and improve the tensile strength and heat resistance of the silicone.

10. Development of new silica
Functionalized silica: Developing silica with special functions (such as antibacterial, self-healing, etc.) can not only improve the mechanical properties of silicone, but also give it additional functional properties.

11. Experimental optimization and characterization
Tensile test: The tensile strength of silicone under different formulations and process conditions is evaluated through tensile tests, and the formulation and process parameters are optimized.
Microstructure characterization: Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and other means are used to observe the dispersion state and interface bonding of silica in silicone, providing a basis for further optimization.