Silica mainly plays the role of flame retardant enhancement and physical property enhancement in silicone flame retardant. The following is a specific analysis of its role:

1. Flame retardant enhancement

Increasing oxygen index:

As an inorganic substance, silica has the property of being non-flammable. When added to silicone rubber, it can reduce the content of combustibles in the composite material, thereby increasing the oxygen index of the material. For example, the oxygen index of pure silicone rubber is very low, only 19.4%, and it is very easy to ignite. After adding silica, the oxygen index of the composite material will increase accordingly. When 50 parts of silica are added, the oxygen index of the composite material can reach 25.0%.

Improving thermal stability:

Adding silica can increase the initial decomposition temperature of the composite material and improve the thermal stability of the material. In thermogravimetric analysis, with the addition of silica, the TG curve shifts to the right as a whole, and T5 and T50 (reaching the maximum decomposition temperature and 50% decomposition temperature, respectively) show an upward trend. This shows that silica can increase the thermal stability of silicone flame retardant, making it more difficult to decompose at high temperatures, thereby slowing down the combustion process.

2. Enhance physical properties

Improve mechanical properties:

Silica in silicone rubber can significantly improve tensile strength, hardness, wear resistance and tear resistance. At the same time, it can also improve the compressive properties of silicone rubber, improve compression deformation rate and elastic recovery. The improvement of these mechanical properties helps silicone flame retardants maintain structural stability when subjected to external forces, thereby more effectively preventing the spread of flames.

Improve processing performance:

The addition of an appropriate amount of silica can improve the processing properties of silicone flame retardants, making them easier to mold and process. However, it should be noted that the amount of silica added needs to be controlled within a certain range, otherwise it may reduce the processability and elasticity of silicone and affect its comprehensive performance.

3. Practical application and effect

Application field:

Silica flame retardants are widely used in wires and cables, building materials, vehicles and other fields, requiring materials to have excellent flame retardant properties and physical properties. The addition of silica can meet these requirements and improve the safety and reliability of products.

Effect evaluation:

Experiments and practical applications have proved that silicone flame retardants with the addition of silica have significantly improved both flame retardant properties and physical properties. At the same time, the addition of silica can also reduce production costs and improve the cost performance of products.

In summary, silica plays an important role in flame retardant enhancement and physical performance enhancement in silicone flame retardants. By reasonably controlling the addition amount and dispersibility of silica, silicone flame retardants with excellent flame retardant properties and physical properties can be prepared to meet the needs of various application fields.