Fumed Silica Reinforcement: Particle Size 7-40 nm

Component Specifications

Definition

Fumed silica reinforcement, also known as pyrogenic silica, is produced through the hydrolysis of silicon tetrachloride in a hydrogen-oxygen flame, resulting in amorphous silicon dioxide nanoparticles with high surface area and purity. In fumed silicone rubber applications, it acts as a thixotropic agent and reinforcing filler, significantly improving tensile strength, tear resistance, hardness, and thermal stability while controlling viscosity and preventing sag during processing.

Working Principle

Fumed silica reinforces silicone rubber through physical adsorption and hydrogen bonding between its surface silanol groups and the polymer chains. The nanoscale particles form a three-dimensional network within the rubber matrix, creating a pseudo-crosslinked structure that enhances mechanical properties without chemical bonding. This network provides reinforcement, improves dimensional stability, and imparts thixotropic behavior (shear-thinning) for better processing.

Materials

Amorphous silicon dioxide (SiO₂) with purity >99.8%, surface area 50-400 m²/g, primary particle size 7-40 nm, aggregated into chain-like structures. Surface may be treated with silanes (hydrophobic) or left untreated (hydrophilic).

Technical Parameters

Parameter	Typical range	Notes & selection driver
PH Value	3.6-4.3 (hydrophilic), 5.0-7.5 (hydrophobic)
Bulk Density	30-60 g/L
Surface Area	50-400 m²/g
Ignition Loss	<2.0% (hydrophilic), <5.0% (hydrophobic)
Particle Size	7-40 nm
Loss On Drying	<1.5%
SiO₂ Content	>99.8%

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 3262-20, ISO 787-11, DIN 55923, ASTM D1993

Parent Products

This component is used in the following industrial products

Fumed Silicone Rubber

A high-performance silicone rubber reinforced with fumed silica, offering enhanced mechanical strength and thermal stability.

View Product Details

Engineering Analysis

Risks & Mitigation

Dust explosion hazard during handling
Respiratory irritation from inhalation
Moisture absorption affecting dispersion
Over-reinforcement leading to brittleness

FMEA Triads

Trigger: Inadequate dispersion during mixing
Failure: Reduced mechanical properties, inconsistent viscosity
Mitigation: Use high-shear mixing equipment, pre-disperse in plasticizer, optimize mixing time/temperature

Trigger: Moisture contamination
Failure: Viscosity increase, processing difficulties, bubble formation
Mitigation: Store in sealed containers, use desiccants, pre-dry material if necessary

Trigger: Excessive loading
Failure: High hardness, reduced elasticity, poor compression set
Mitigation: Optimize formulation through DOE, balance with other fillers/plasticizers

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±5% on specified surface area and pH values

Test Method

Surface area by BET nitrogen adsorption (ISO 9277), particle size by laser diffraction (ISO 13320), pH by suspension method (ISO 787-9)

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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Manufacturers of Fumed Silica Reinforcement

Manufacturer profiles associated with Fumed Silica Reinforcement.

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Related Components

Mold Release Coating

Specialized coating applied to molds to facilitate easy release of silicone seal rings during manufacturing.

Silicone Polymer Base

Silicone polymer base is a high-temperature resistant polymer material used as the foundational component in silicone rubber compounds for industrial applications.

Reinforcing Filler

Reinforcing filler is a material added to silicone rubber compounds to enhance mechanical properties, thermal stability, and durability in high-temperature applications.

Processing Aids

Processing aids are specialized additives used to improve the manufacturability and performance of high-temperature silicone rubber compounds during industrial processing.

Frequently Asked Questions

What is the difference between hydrophilic and hydrophobic fumed silica?

Hydrophilic fumed silica has untreated surface silanol groups, making it compatible with polar systems. Hydrophobic fumed silica is surface-treated with silanes, reducing moisture sensitivity and improving dispersion in non-polar polymers like silicone rubber.

How does fumed silica improve silicone rubber processing?

It provides thixotropic behavior, preventing sag during extrusion or molding while allowing easy flow under shear. This improves shape retention, reduces defects, and enhances productivity.

What are the typical loading levels in silicone rubber?

Typically 5-30 phr (parts per hundred rubber), depending on desired hardness, viscosity, and reinforcement. Higher loadings increase strength but may reduce elongation.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Fumed Silica Reinforcement