The use of GENIOSIL® GF 31 as a coupling agent in glass fiber-reinforced or filler-modified plastics improves filler dispersibility while reducing the filler's sedimentation tendency. It also results in a major reduction in the melt viscosity of casting resins, as well as a marked improvement in the mechanical properties of glass-fiber-reinforced or mineral-filled plastics. In addition, use of GENIOSIL® GF 31 in these materials leads to a sizable increase in moisture (vapor) resistance as well as greater resistance to acids and bases. Used as a co-monomer in polymers, GENIOSIL® GF 31 produces binders that exhibit much improved wet scrub, abrasion and scratch resistance thanks to crosslinking and strong adhesion to the base. As a component of free-radical curable adhesives and sealants, GENIOSIL® GF 31 leads to improved mechanical properties and enhanced substrate adhesion.

GENIOSIL® GF 31 is an alkoxysilane with a methacrylic organofunctional group. It´s a clear, colorless, light and heat sensitive liquid with a characteristically sweet odor. The silane hydrolyzes in the presence of moisture (methanol is released) to form silanols, which can then react with themselves to produce siloxanes. As a bifunctional, organically unsaturated molecule, GENIOSIL® GF 31 can be incorporated into organic polymers, e.g. via radical grafting.

1. General processing information

GENIOSIL® GF 31 is highly miscible with standard organic solvents, such as alcohols, toluene and acetone.
GENIOSIL® GF 31 is practically insoluble in neutral water.
However, by adjusting the pH to between 3 and 4 with a hydrolysis catalyst (e.g. acetic acid), an aqueous solution of up to 5 percent by weight can be obtained. The resulting clear solution should be used as soon as possible (within 1-2 days), before siloxane formation has proceeded too far. Deactivation of GENIOSIL® GF 31 by siloxane formation is signalized by clouding of the aqueous solution.

2. GENIOSIL® GF 31 in glass-fiber reinforced or mineral-filled polymers

Fillers are treated either with pure GENIOSIL® GF 31 or a solution thereof. It may be necessary to pretreat the substrate with water and/or a catalyst.
Subsequent binding of the treated filler to unsaturated polyester resins, for example, is preferably effected via peroxide or radiation initiated copolymerization or grafting.
In an alternative procedure referred to as "blending", GENIOSIL® GF 31 is added directly to the polymer - either before the organic materials is compounded with the filler or at the same time.
A prerequisite for the blending process is that GENIOSIL® GF 31 and the polymer are compatible and that the resin and GENIOSIL® GF 31 do not react prematurely.

3. GENIOSIL® GF 31 as a surface modifier

Used as a primer, GENIOSIL® GF 31 is applied as an aqueous or organic solution to an inorganic substrate (e.g. metal or glass surfaces). Once GENIOSIL® GF 31 has dried and bonded to the surface, an organic coating may be applied using a standard technique (e.g. spraying or knife coating).

4. GENIOSIL® GF 31 as a polymer building block

To incorporate GENIOSIL® GF 31 in organic polymers, it is added as a co-monomer - along with typically used monomers and free-radical initiators such as diazo compounds or peroxides - during production of the solution or emulsion polymer. Promoters (e.g. cobalt compounds) can give additional impetus to the radical grafting of GENIOSIL® GF 31 to organic polymers. The polymers obtained in this way can be formulated as coatings, adhesives or sealants.

GENIOSIL® GF 31 is mainly used in glass fiber or glass fabric-reinforced polyester and polyolefin molded components.
In addition, GENIOSIL® GF 31 is used as a surface modifier for fillers and pigments used in thermosetting plastics (e.g. polyacrylates, polyesters), thermoplastics (polyesters, polyolefins) and elastomers, as well as a polymer component in surface coatings.
Further important areas of application are heat and/or radiation-curable adhesives and sealants.


Information on available container sizes is obtainable from WACKER subsidiaries.


The 'Best use before end' date of each batch is shown on the product label.

Storage beyond the date specified on the label does not necessarily mean that the product is no longer usable. In this case however, the properties required for the intended use must be checked for quality assurance reasons.

Sales and support

Wacker Chemical Corporation
3301 Sutton Road
Adrian, MI 49221-9397
United States
+1  888  922-5374 (Phone)

How can we help you?

  • Do you need help in choosing a product or do you require technical support? If so, please contact our experts.
Ask a question


My media

My favorites

My products