How to add silica nanoparticles into rubber materials?

The mechanical strength of pure rubber is quite low. However, the tensile strength of vulcanized rubber can be improved from 0.35MPa to 14MPa and reinforcement rate can be 40 times higher than common rubber when the rubber is mixed with nano silica to reinforce mechanical strength.

Nano silica is the best filler which can reinforce high temperature vulcanized silicone rubber. After adding our nano silica for rubber use, silica nanoparticles aggregates on the silicone rubber to form microcrystalline with silicon dioxide as nucleation zone, which increases the physical cross linking points and make it easier for crystallization. By adding nano SiO2,the rubber strength can be increased 40 times.

1. As a reinforcing agent, anti-aging agent, nano silica can be used in rubber products to increase strength, toughness, anti-aging, anti-friction of rubber products and prolong life and other functions
2. Nano silica is an effective reinforcing filler of RTV silicone rubber, which can significantly improve their strength. On one hand, it is because of the small particle size and large surface area of SiO2 nanoparticles. On the other hand, the surface of silica nanoparticles contain a lot of –SiOH groups and these particles can form a network structure through hydrogen bonding and van der Waals forces. In the meantime, silica nanoparticles will have a strong interaction with polysiloxane molecules to improve the interface condition. The reinforcement effect on silicone rubber depend on particle size, specific surface area and structure of SiO2 nanoparticles. Usually, SiO2 nanoparticles with smaller particle size will have larger specific surface area, better structure and reinforcing effect, which help imrpove vulcanized rubber with higher strength and hardness.

Silicone rubber: 3.0-30%;
Polysulfide rubber: 0.1-5%;
Polyurethane: 3.0-25%;
Acrylate rubber: 0.5-3.5%

Evenly mix raw rubber, hydroxyl silicone oil and silica nanopowder in a two-roll mixing mill according to the formula ratio until get a thin film. Treat the film at 170 ℃ for 2 hours and put it in the mixing mill for a second mixing until a thin film by adding vulcanizing agent. Next day, modeling the film on the vulcanization molding machine. The vulcanizing condition is 175 ℃ × t90. T90 is measured curing time for LH-90 type of vulcanized rubber vulcanization

When add silica nanopowder, its dispersion degree in a polymer must be paid attention to. The degree of SiO2 dispersion will have a great effect on rubber properties. In transparent rubber material system, higher transparency indicates better dispersion of silica nanoparticles.