Vinyltrimethoxysilane (A-171 / KH-171)

Vinyltrimethoxysilane (VTMS, A-171/KH-171) is a fast-hydrolyzing organosilane coupling agent with a vinyl group for co-reaction with unsaturated polymer systems and three methoxy groups for rapid bonding to glass, silica, and mineral substrates. The trimethoxysilane groups hydrolyze 5–10× faster than the corresponding triethoxysilane (A-151), making A-171 the preferred choice for aqueous fiber sizing applications, fast-cycling composite processes, and any system where rapid silane-substrate interaction is required.

The faster hydrolysis rate of VTMS makes it particularly effective in aqueous sizing solutions applied to glass fiber rovings and woven fabrics. In sizing, A-171 provides excellent fiber-resin coupling in UPR, VER, and styrene-based thermoplastic composites, improving wet interlaminar shear strength, flexural strength retention, and resistance to fatigue in cyclic loading. At equivalent application concentration, A-171 typically gives marginally better short-term performance than A-151 due to more complete surface coverage from faster hydrolysis.

A-171 is also widely used as a crosslinking agent in moisture-crosslinked polyethylene (XLPE) cable insulation. When grafted onto polyethylene and exposed to atmospheric moisture, the vinyl-silane-grafted PE undergoes Si-O-Si crosslinking, creating a three-dimensional thermoset-like network without requiring peroxide curing equipment. This application makes VTMS one of the highest-volume organosilanes globally.