N-(2-Aminoethyl)-3-Aminopropyltrimethoxysilane (A-1120)

A-1120 is a diamine-functional organosilane coupling agent containing both a primary amine and a secondary amine in its functional chain. This diamine structure provides two reactive sites per molecule for reaction with epoxy groups, yielding a higher crosslink density at the filler-resin interface compared to monoamine silanes like A-1100. The higher amine functionality per molecule makes A-1120 a more potent coupling agent for demanding epoxy applications.

The diamine structure of A-1120 contributes significantly higher basicity compared to A-1100, making it the preferred silane for glass fiber sizing in high-performance epoxy composites where maximum wet strength retention is critical. In wind turbine blade composites and aerospace structures, A-1120-sized glass fiber typically outperforms A-1100-sized fiber in long-term hydrothermal aging, providing better interlaminar shear strength retention after extended hot-wet conditioning.

For mineral filler and substrate treatment, A-1120 provides enhanced reactivity with epoxy systems, producing more fully crosslinked interfacial zones. This can improve impact resistance and fatigue life of filled epoxy composites beyond what monoamine silanes achieve. A key consideration is the higher viscosity of A-1120 compared to A-1100 and its strong tendency to form self-condensation products in the presence of moisture — careful storage and handling in sealed containers under nitrogen are essential.