AEROSIL® fumed silica – Beneficial for rheological propertie

Get in the flow with AEROSIL® fumed silica:

  • Viscosity

  • Extrudability

  • Rigidity

  • Thixotropy

  • Flowability

  • Storage stability

Silicone rubber and AEROSIL® fumed silica - and no thickening?
Rheological properties

AEROSIL® products allow for the precise adjustment of rheological properties (e.g. low thickening) of silicone applications. This is particularly important for very low-viscosity and flow-enabled systems such as liquid silicone rubber (LSR) or RTV-2C systems (casting and impression compounds). Low viscosity is not only required during processing, but extended storage times must also be possible without a significant increase in viscosity. 

Thanks to its special modification processes of hydrophilic fumed silica, Evonik Industries AG is able to offer strongly hydrophobic (e.g. AEROSIL® R 812 S) or even strongly hydrophobic and structurally modified products (e.g. AEROSIL® R 8200) that meet these demanding requirements.

Thickening control of silicone rubber thanks to AEROSIL® fumed silica!

The accurate application of RTV-1C silicone sealing compounds requires a certain level of viscosity, an exactly defined extrusion rate (extrusion capacity) and a certain stability (flow limit or yield point) to ensure that the sealant remains in the desired place (e.g. in a wall joint) during application. 
These effects generated by AEROSIL® fumed silica are called as thixotropy. Evonik offers hydrophilic AEROSIL® products such as e.g. AEROSIL® 150 for RTV-1C silicone sealant. The use of hydrophobic types such as AEROSIL® R 972 also allows for generating neutral-curing silicone sealants (e.g. alcoxy cured systems) with a good storage stability (shelf-life). Hydrophobic products with larger surface area such as AEROSIL® R 106 or AEROSIL® R 812 S are particularly suitable for transparent silicone sealants.