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When a silicone rubber or sealant manufacturer considers a new hydrophobic fumed silica supplier, the main concern is often not simply the price.
The bigger question is:
Can the new silica provide comparable processing and final-performance behavior without forcing a major formulation change?
A structured qualification process can reduce this risk.
BET surface area is important, but it does not describe the complete behavior of hydrophobic fumed silica.
When evaluating a replacement grade, it is useful to compare:
Two products with similar BET values may still behave differently in an actual formulation.
Hydrophobic fumed silica is surface-treated to modify its interaction with the surrounding formulation.
The type and degree of surface treatment can affect:
Therefore, when qualifying a new supplier, ask for information about the surface-treatment technology rather than comparing only the product name.
A practical qualification method is to keep the existing formulation unchanged during the initial comparison.
Compare the new silica against the current material under the same conditions.
For example:
Current silica → New silica
Then compare:
This makes it easier to identify whether any performance difference comes from the silica itself.
Different applications may require different silica characteristics.
Hydrophobic fumed silica can be used in areas such as:
For example, IOTA HB7135 is a hydrophobic fumed silica produced by surface treatment of hydrophilic silica. It is designed for applications including silicone rubber, adhesives and sealants, defoamers and toner.
The appropriate grade still depends on the formulation and processing requirements.
A useful supplier qualification package should include:
More importantly, the supplier should be able to discuss the application rather than only provide a product specification sheet.
Not always. Even similar grades can produce different processing or rheological behavior. A controlled trial is recommended.
No. BET is an important parameter, but surface treatment and actual application performance should also be considered.
Differences in surface treatment, structure, dispersion and other material characteristics can influence formulation behavior.
It is often useful to keep the existing formulation unchanged during the initial comparison. This makes the performance difference easier to evaluate.
Compare technical data, obtain samples and conduct side-by-side testing using the existing formulation and processing conditions.
Final grade selection should be based on the actual formulation, processing conditions and finished-product requirements.
