Evonik re-launched the product AEROSIL® 300 SP. The use of AEROSIL® SP fumed silica can improve the transparency of silicone rubber without sacrificing mechanical properties.
The AEROSIL® SP fumed silica grades exhibit properties of pyrogenic and morphology colloidal silicas. Still made through the pyrogenic process, the aggregate/agglomerate structure is altered and the particle size distribution is narrower than standard grades of similar surface area. This process also results in an agglomerate structure that requires less shear force to be applied to achieve equal dispersion. As this force is typically predetermined by the available equipment, this will reduce the time to properly disperse this grade of fumed silica as compared to similar surface area materials.
AEROSIL® 200 SP and AEROSIL® 300 SP have similar physicochemical properties as our established products, AEROSIL® 200 and AEROSIL® 300. There is no change in BET surface area, LoD or tapped density.
The transparency of silicone formulations mainly depends on two factors: particle size distribution of the silica and refractive index of the polymer and filler. Our structure modification process at a given particle size and BET surface area can further improve transparency of various silicone systems such as HTV, LSR and two-component silicone rubbers significantly.