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Thanks to AEROSIL® fumed silica, silicone rubber is colorless and highly transparent. This has resulted in the material being used in a wide range of applications for purely esthetic reasons. Silicone rubber can be pigmented to almost any color, but highly transparent formulations are also commercially available. These are used for medical applications, such as tubes and catheters, but are also preferred in products for daily use such as nipples for baby bottles and diving goggles.
The transparency of such formulations is controlled essentially by two factors: the particle size of the silica and the refractive index of the polymer or filler. AEROSIL® grades such as AEROSIL® 300 have a relatively high specific surface area are especially suitable for highly transparent silicone systems. By modifying the fumed silica surface with silanes or silicones, the refractive index can be adjusted so that it is similar to that of silicone rubber, therefore improving the transparency of the silicone system.
AEROSIL® R 106 and AEROSIL® R 812 S are examples of extremely hydrophobic materials that make is feasible for high-transparency products.
Additionally Evonik offers a wide range of functional silanes under the brand name Dynasylan®. If you would like to get more information about our Dynasylan® grades, please use the following link: Dynasylan®
Industry Information 2247: Materials for the Silicone Rubber Industry
Technical Information 1148: AEROSIL® R 104 and AEROSIL® R 106 for silicone rubber applications
Technical Information 1209: AEROSIL® R 8200 for Silicone Rubber
Technical Information 1253: AEROSIL® and AEROXIDE® for Liquid Silicone Rubber (LSR/LIMS)
Technical Information 1374: Products for 1-component RTV silicone sealant compounds
Product- as well as safety data sheets (SDS) of our various AEROSIL® fumed silica grades, can be found at our product recommendationsmore