In glass fiber reinforced unsaturated polyester composites, interfacial bonding strength is often the key factor determining overall performance. Poor interfacial bonding allows moisture to easily penetrate, leading to a sharp decline in material performance in humid environments. IOTA-5563 is precisely the "molecular glue" that solves this problem.

Its mechanism of action can be divided into two steps:

1. Hydrolysis and condensation: The methoxy group (–OCH₃) of IOTA-5563 hydrolyzes to silanol (–SiOH) in the presence of trace amounts of moisture, subsequently condensing with the hydroxyl groups (–OH) on the glass fiber surface to form stable Si–O–Si covalent bonds;

2. Epoxy ring-opening reaction: The epoxy group at the other end of its molecule reacts with the carboxyl or amine initiators in the unsaturated polyester during curing, embedding itself into the organic resin network.

This structure, which "grabs inorganic matter on one end and connects to organic matter on the other," upgrades the interface from physical adsorption to chemical bonding, thereby significantly improving:

- Interlaminar shear strength (ILSS)
- Wet flexural strength retention rate
- Electrical insulation stability (especially in high humidity environments)

Experiments show that composite materials with the addition of 0.5–2% IOTA-5563 can improve their wet mechanical properties by more than 30%, significantly extending product lifespan.