Reinforcing fillers not only significantly improve the mechanical strength in silicone rubber, but also improve the overall performance of the material through a variety of mechanisms. The specific effects are as follows：


1. Improve processing performance
Rheological regulation: The nanoscale particles of reinforcing fillers (such as fumed silica) can form a three-dimensional network structure and regulate the viscosity and fluidity of silicone rubber.For example, adding a small amount of silica can reduce the fluidity of the rubber compound and prevent it from collapsing during molding; and surface modification (such as silane coupling agent treatment) can balance the processability and reinforcement effect.
Optimization of mold release: Some fillers (such as zinc stearate) can be used as lubricants to reduce the adhesion of silicone rubber to the mold and improve production efficiency.
2. Enhanced thermal stability
Inhibition of thermal decomposition: Reinforcing fillers (such as silica and carbon black) have high thermal stability, can form a physical barrier, and delay the thermal oxidation and degradation of the main chain of silicone rubber (Si-O-Si).For example, adding 40 parts of silica can increase the initial decomposition temperature (T5) of silicone rubber from 450℃ to 495℃.
Thermal conductivity adjustment: Metal oxide fillers (such as alumina and zinc oxide) can improve the thermal conductivity of silicone rubber, which is suitable for heat dissipation scenarios (such as LED packaging).
3. Improve aging resistance
Ultraviolet shielding: Fillers such as carbon black and titanium dioxide can absorb or reflect ultraviolet rays to prevent the silicone rubber from yellowing and cracking due to light oxidation.For example, adding 5 parts of carbon black can extend the outdoor service life of silicone rubber by 3-5 times.
Ozone resistance: Carbon black filler can adsorb ozone molecules, inhibit their attack on the double bond of silicone rubber, and significantly improve the durability of the material in dynamic sealing scenarios.
4. Give special functions
Conductivity: Adding conductive carbon black, graphene or metal powders (such as silver and copper) can make silicone rubber conductive and used in electromagnetic shielding, flexible electrodes and other fields.For example, the volume resistivity of silicone rubber filled with conductive carbon black can be as low as 102 Ω·cm.
Magnetism: Magnetic fillers such as ferrite and neodymium iron boron can impart magnetic responsiveness to silicone rubber, which is suitable for sensors and magnetic seals.
Flame retardant: Inorganic fillers such as aluminum hydroxide and magnesium hydroxide decompose and absorb heat at high temperatures, and release flame-retardant gases (such as water vapor) to make silicone rubber reach UL94 V-0 flame retardant standards.
5. Optimize dynamic performance
Fatigue resistance: The reinforcing filler can reduce the molecular chain slip of silicone rubber during repeated deformation, and reduce the dynamic fatigue and heat generation.For example, adding 30 parts of silica can reduce the compression permanent deformation rate of silicone rubber from 40% to 15%.
Wear resistance: Hard fillers such as nano-silica and silicon carbide can improve the hardness of the surface of silicone rubber and reduce wear.For example, adding 20 parts of silicon carbide to silicone rubber can reduce wear by 60%.
6. Cost reduction and resource utilization
Filler substitution: Some fillers (such as diatomaceous earth and calcium carbonate) can replace part of the silicone rubber matrix to reduce the cost of raw materials.For example, adding 50 parts of calcium carbonate can reduce the cost of silicone rubber by 30% while maintaining basic performance.
Utilization of renewable resources: industrial waste such as rice husk ash and fly ash can be used as reinforcing fillers after treatment to realize resource recycling.
7. Enhanced environmental adaptability
Chemical resistance: Fillers (such as mica and talcum powder) can fill the gaps between the molecular chains of silicone rubber to prevent the penetration of chemical media.For example, adding 20 parts of mica can increase the solvent resistance of silicone rubber by 50%.
Low temperature resistance: By adjusting the type of filler (such as low phenyl silicone oil) and particle size distribution, the flexibility of silicone rubber at low temperatures can be improved and brittleness can be avoided.