Description

Fumed Silica CAS NO 99439-28-8 is a high-purity, synthetic amorphous silicon dioxide produced by the vapor-phase hydrolysis of silicon tetrachloride in a hydrogen-oxygen flame. This material is critical for its exceptional ability to act as a versatile rheology modifier, thixotropic agent, and reinforcing filler. It is an essential component for formulators and manufacturers in industries such as adhesives & sealants, coatings, composites, pharmaceuticals, and personal care, where precise control over viscosity, anti-settling, and mechanical properties is required.

Application

• Adhesives & Sealants: Provides thixotropy, prevents sagging, and reinforces the matrix.
• Coatings & Inks: Acts as an anti-settling agent, controls flow and leveling, and enhances durability.
• Silicone Rubber & Elastomers: Serves as a primary reinforcing filler to dramatically improve tensile strength and tear resistance.
• Pharmaceuticals: Used as a tablet disintegrant, glidant, and viscosity-increasing agent in topical preparations.
• Personal Care & Cosmetics: Functions as a thickener, anti-caking agent, and provides a silky feel in creams, lotions, and powders.
• Unsaturated Polyester Resins (UPR) & Gel Coats: Imparts thixotropy to prevent drainage on vertical surfaces.
• Food & Feed: Acts as an anti-caking and free-flow agent for powdered ingredients (food-grade grades available).
• Industrial & Chemical Processes: Used as a carrier for catalysts, a viscosity modifier in lubricating greases, and in defoamer formulations.

Basic Information

Product Name	Fumed Silica
CAS No.	99439-28-8
Molecular Formula	SiO₂
Molecular Weight	60.08 g/mol
Synonyms	Pyrogenic Silica; Colloidal Silicon Dioxide; Amorphous Fumed Silica; Silica, Fumed; Aerosil® (common trade name); Cab-O-Sil® (common trade name); Hydrophilic Fumed Silica; Synthetic Amorphous Silica (SAS)
EINECS	Contact for details

Quality Control

Our Fumed Silica is manufactured under a stringent quality management system. Each batch undergoes rigorous testing for key parameters including purity, surface area, bulk density, and loss on drying to ensure consistent performance. Certificates of Analysis (COA) are provided with every shipment. We can supply grades compliant with relevant standards such as USP/NF for pharmaceutical applications and FCC for food contact, upon request.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, and well-ventilated area at room temperature (15-25°C). This product is hygroscopic (moisture-sensitive); keep the container tightly sealed when not in use to prevent moisture absorption and caking.

Specification

Item	Specification
Appearance	White, fluffy powder
Assay (SiO₂)	≥ 99.8%
Surface Area (BET)	50 - 400 m²/g (grade dependent)
Loss on Drying (105°C)	≤ 1.5%
pH (in 4% suspension)	3.5 - 4.5
Tamped Density	30 - 100 g/L (grade dependent)
Sieve Residue (45μm)	≤ 0.05%
Heavy Metals (as Pb)	≤ 10 ppm

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.