XYSIL® fumed silica for silicone rubber

XYSIL® fumed silica is an efficient reinforcement and rheology control additives for silicone rubber.

Benifit from the unique particle characteristics, XYSIL® fumed silica delivers superior reinforcement while having a relatively minor impact on transparency. The silicone rubber performance is impacted by primary particle size, aggregate size, and surface chemistry.


Xunyu offers a range of untreated fumed silica for optimum performance in silicone applications including:

  • Room Temperature Vulcanizing (RTV) Silicone Sealant
  • High Temperature Vulcanizing (HTV) Silicone Rubber
  • Liquid Silicone Rubber (LSR)

In RTV silicone sealant

XYSIL® fumed silica provides thixotropy and reinforcement for RTV silicone sealants, while its shear-thinning property provides thickening and sag resistance at rest or low shear and thinning at high shear for easy application.

In HTV silicone rubber and LSR

XYSIL® fumed silica strengthens the cured rubber, increasing hardness, modulus, tensile strength and tear strength. Unlike other reinforcing fillers, XYSIL® fumed silica can be used in transparent or clear applications.

silicone rubber in cellphone case and watch belt

As the surface area of fumed silica increases, so does thickening and reinforcement. However, high surface area XYSIL® fumed silica requires high shear dispersion equipment to achieve optimal performance. In general, XYSIL® 150 is used in RTV silicone sealant; XYSIL®200 and XYSIL®300 are used in HTV silicone rubber and LSR.

Fumed Silica XYSIL® for Silicone Rubber

Sytem XYSIL® Grade Concentration in wt.% Effect
RTV-1 Silicone Sealant XYSIL®150
3.0-30 Reinforcement, Thixotropy
RTV-molding compound(2 components) XYSIL®200 3-30 Reinforcement, Thixotropy
HTV Silicone Rubber XYSIL®200 5.0-35 Reinforcement, sag resistance, dispersability, surface quality, life duration
Liquid Silicone Rubber XYSIL®200
5-30 Rheology control, sag resistance, reinforcement, anti-settling