3-Glycidoxypropyltrimethoxysilane (A-187 / KH-560)

3-Glycidoxypropyltrimethoxysilane (GPS, A-187/KH-560) is the standard silane coupling agent for epoxy resin systems. Its glycidyl ether functional group is directly compatible with epoxy chemistry, reacting with amine, anhydride, and phenolic hardeners during cure to form chemical bonds between the epoxy matrix and glass or mineral filler surfaces. This compatibility makes GPS the optimal choice for epoxy-based adhesives, coatings, and fiber-reinforced composites.

In glass-fiber-reinforced epoxy laminates (used extensively in aerospace, wind energy, and electronics), GPS sizing on glass fiber significantly improves dry and wet interlaminar shear strength (ILSS), flexural strength, and resistance to delamination under hydrothermal aging. Improved interfacial toughness from the GPS coupling also reduces microcracking under thermal cycling, which is critical in aerospace structural composites subjected to wide temperature ranges.

For mineral filler treatment in epoxy systems, GPS treatment of ATH (for halogen-free FR epoxy), silica, wollastonite, and calcined kaolin dramatically improves mechanical performance, particularly in hot-wet environments. The treatment prevents hydrolytic failure at the filler-matrix interface that untreated fillers are susceptible to. GPS is also used as an adhesion promoter in epoxy coatings on glass, metal, and ceramic substrates, and as a crosslinker in waterborne epoxy systems.