Plastics & Polymers / Solution Family

Precipitated & Treated Silica

Precipitated and surface-treated synthetic amorphous silicas for rubber reinforcement, polymer thickening, and anti-settling u2014 hydrophilic and hydrophobic grades for filled and liquid systems.

Overview

Treated and precipitated silicas are fine synthetic amorphous silicas used innpolymers to reinforce, thicken, and control settling. Precipitated silica is thenworkhorse reinforcing filler for rubber; surface-treated (hydrophobic) fumed silica is thenrheology and anti-settling additive for filled and liquid systems. The dividing line isnsurface chemistry: a hydrophilic surface bonds water and polar groups, while ansilane-treated hydrophobic surface disperses into non-polar resins and rubber. Match thensurface to the polymer, not just the particle.

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Precipitated silica (CAS 112926-00-8) is the reinforcing filler behind silica-tirentechnology and a wide range of technical rubber goods. It raises tensile strength, tearnresistance, and abrasion resistance, and in tire treads it lowers rolling resistance versusncarbon black. The honest trade-off: its hydrophilic surface resists dispersion in non-polarnrubber and pushes compound viscosity up, so it is almost always run with a sulfur-functionalncoupling silane such as TESPT. Specify it where wet grip and rolling resistance matter.

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Surface-treated fumed silica (CAS 68909-20-6) carries the same reinforcing structure withna silane-modified, water-repelling surface. That treatment lets it disperse into resins,nadhesives, and liquid silicones without absorbing atmospheric moisture, where it buildsnthixotropic viscosity and stops fillers and pigments from settling. Treated grades cost morenthan untreated silica and interact less with polar binders. Reserve them for non-polar ornmoisture-sensitive systems; for aqueous or polar formulations, an untreated hydrophilic gradenis usually the better and cheaper choice.

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Where it's used
  • Reinforcing filler for tire treads, technical rubber goods, and elastomer compounds
  • Thixotropic rheology and anti-sag control in adhesives, sealants, and liquid resins
  • Anti-settling and pigment-suspension aid in filled polymer and coating systems
  • Reinforcement of liquid silicone rubber (LSR) and high-consistency silicone compounds
  • Anti-caking and free-flow additive in polymer powders and masterbatch
Frequently asked questions
What is the difference between precipitated silica and treated fumed silica?
Precipitated silica is a hydrophilic reinforcing filler used mainly in rubber, where it raises strength and (in tires) lowers rolling resistance. Treated fumed silica has a silane-modified, water-repelling surface, so it disperses into resins and liquid silicones and builds thixotropic viscosity without absorbing moisture. Choose precipitated silica for rubber reinforcement and treated fumed silica for rheology and anti-settling in non-polar systems.
Why is precipitated silica used with a coupling silane in rubber?
Precipitated silica's hydrophilic surface does not bond well to non-polar rubber and raises compound viscosity. A sulfur-functional coupling silane such as TESPT chemically links the silica to the rubber network, which improves dispersion, lowers viscosity during mixing, and is what makes silica-tire treads deliver low rolling resistance with good wet grip.
When should I choose a hydrophobic (treated) silica over an untreated grade?
Use a hydrophobic, surface-treated silica in non-polar or moisture-sensitive systems u2014 solvent-borne resins, adhesives, sealants, and liquid silicones u2014 where it disperses cleanly and resists moisture pickup. For aqueous or polar formulations an untreated hydrophilic grade usually performs as well at lower cost. Treated grades carry a price premium, so match the surface to the polymer.
Does RawSource supply precipitated and treated silica in bulk?
Yes. RawSource sources precipitated silica, hydrophobic surface-treated fumed silica, and dimethyl-silylated silica to bulk RFQ. Send the surface type (hydrophilic or hydrophobic), target surface area or thickening behavior, and packaging, and our procurement team will quote against your specification.
Disclaimer. Information on this page is provided for general reference and compiled from authoritative public sources (e.g. PubChem/ECHA). Values are typical and are not a guaranteed specification; the Certificate of Analysis (CoA) for the lot you purchase governs. Products are sold for industrial and professional use only. Nothing here is a medical, health, or efficacy claim. Always consult the current Safety Data Sheet (SDS) before handling, and confirm regulatory status, classification, and suitability for your application and jurisdiction.
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