Vinyltrimethoxysilane, is used as a polymer modifier via grafting reactions. The resulting pendant trimethoxysilyl groups can function as moisture-activated crosslinking sites. The silane grafted polymer is processed as a thermoplastic and crosslinking occurs after fabrication of the finished article upon exposure to moisture.
Crosslinking of Silane-Grafted Polymers:
The reaction of Silane-grafted polyethylene to form a crosslinked or vulcanized polyethylene uses water to form the crosslinks. This technology is widely used around the world for commercial applications in wire and cable insulation, tubing, and other similar uses.
The basic reaction sequence is as follows:
polyethylene is reacted (grafted) with vinyltrimethoxysilane, using a peroxide initiator, in an extruder. The grafted polyethylene is then formed into a finished product, such as cable jacketing, wire insulation, or pipe. The forming step is usually done by a second extrusion, during which a catalyst for the moisture-cure step is added. Finally, the formed article is exposed to moisture or hot water to cause hydrolysis of the silane and condensation to form crosslinks via Si-O-Si bond formation.
This product can be applied to polythene and copolymer with various complex shapes in all densities, and also can be used in the large processing technique tolerance and composites filler etc. It is with high operating temperature, excellent compressive resist memory function, abrasion resistance and shock resistance. It can be grafted to the main chain of the polymer to modify polyethylene and other polymers, and then the side chain would get the ester group, as the active point of warm water crosslink. The grafted polyethylene can be made into mature products, such as cable insulations, tubes or other extruding and pressing products etc.