Vinyltrimethoxysilane (VTMS) CAS 2768-02-7

Introduction to Vinyltrimethoxysilane

Vinyltrimethoxysilane (VTMS) is a low-viscosity reactive silane with a polymerizable vinyl group bonded to a silicon atom bearing three methoxy substituents. In two-step silane crosslinking, the vinyl group grafts onto polyethylene chains under peroxide initiation, while methoxy groups hydrolyze and condense to form a stable Si-O-Si network. It is widely used to convert thermoplastic PE into thermoset materials with upgraded thermal and mechanical performance.

Its fast methoxy hydrolysis kinetics significantly shorten warm-water cure cycles. The material is highly moisture sensitive: trace water reacts with methoxy groups to release methanol and form siloxane oligomers, causing cloudiness and reduced reactivity. Store under nitrogen blanket at 10–25 °C, keep drums tightly sealed and use opened containers within 48 hours.

Vinyltrimethoxysilane Chemical & Physical Properties

Applications of Vinyltrimethoxysilane

Silane-crosslinked polyethylene pipes
Used in crosslinked PE plumbing and heating pipe production. It grafts onto the polymer backbone and forms a three-dimensional network during curing, raising heat distortion temperature and improving long-term hydrostatic strength of finished pipes.

Wire and cable insulation
Added to polyethylene insulation compounds for wire and cable products. The crosslinked structure preserves dielectric performance and mechanical integrity under thermal stress, supporting halogen-free insulation solutions.

Fiberglass sizing & composite treatment
Applied in fiberglass sizing formulations. It bonds to glass fiber surfaces and co-reacts with resin matrices during composite molding, improving flexural strength and wet performance of reinforced materials.

Sealant & coating adhesion promoters
Incorporated into silicone and polyurethane sealants and coatings. It improves adhesion to metal, glass and other substrates, enhancing peel strength and long-term humidity resistance.

Storage & Safety Precautions for Vinyltrimethoxysilane

• Store tightly sealed under nitrogen at 10–25 °C, away from moisture, acids and oxidizers. Use opened drums within 48 hours to prevent premature hydrolysis and reactivity loss.
• Classified as flammable liquid with acute inhalation hazard. Wear chemical-resistant gloves, splash goggles and organic vapor respirator during handling. Ensure explosion-proof ventilation in work areas.
• Classified as UN 1993, Class 3 for transport. Ship in approved containers with proper dangerous goods labeling.
• Verify purity and water content upon receipt. Reject cloudy material or lots with elevated water content, which indicate premature hydrolysis.

Vinyltrimethoxysilane FAQ

Q: Why does VTMS turn cloudy inside the drum?

A: Moisture ingress triggers premature hydrolysis of methoxy groups, forming siloxane oligomers. Cloudy VTMS has reduced grafting efficiency. Store under nitrogen and reject out-of-spec material.

Q: How does VTMS perform in PE crosslinking cure speed?

A: Its methoxy groups hydrolyze rapidly, cutting cure time by 30–40% at 90 °C compared to slower silanes, which fits high-speed production lines.

Q: What dosage range works for PE-Xb pipe production?

A: Standard loading falls in a moderate range. Too little reduces gel content; too much adds cost without strength gains and may cause die buildup.