he vulcanization reaction of RTV one
is initiated by moisture in the air. The commonly used cross-linking agent is methyl triacetoxysilane, whose Si-O-C bond is easily hydrolyzed. Acetoxy and hydrogen groups in water are combined to form acetic acid, and hydroxyl groups in water are moved to the original acetoxy position to become trihydroxymethyl silane. Ordinarily, organosilicon raw rubber containing terminal group of silanol, fillers, catalysts, cross-linking agents and other complexes are put into sealed hoses. When used, they are extruded from containers, vulcanized into elastomers using moisture in the air, and low molecular weight substances are released at the same time. When crosslinked with an alkoxy group, alcohols are released, which is called a dealcoholic RTV one
. When crosslinked with the oxime group, oxime is formed, which is called dioxide room temperature vulcanized silicone rubber. Therefore, with the different cross-linking agents, RTV one
can be used as deacidification, dioxide, dealcoholization, diamine, deamidation, and diketone, but deacidification is the most widely used one at present.
The curing time of RTV one
depends on the curing system, temperature, humidity and the thickness of the silicone rubber layer. Increasing the temperature and humidity of the environment can accelerate the curing process. Under typical environmental conditions, the surface of silicone rubber can be non-sticky after 15-30 minutes, and the rubber layer with a thickness of 0.3 cm can be cured in one day. The curing depth and strength will gradually increase in about three weeks.
has excellent electrical properties and chemical inertia, as well as heat resistance, natural aging resistance, flame resistance, moisture resistance, air permeability, and other properties. They can keep elasticity for a long time in the range of - 60 - 200 C. It does not absorb heat and exothermic when curing and has small shrinkage rate after curing, and good adhesion to materials. Therefore, it is mainly used as adhesives and sealants. Other applications include in-situ forming gaskets, protective coatings, and seam materials.
The vulcanization reaction of RTV one
proceeds from the surface to the depth gradually. The thicker the rubber
layer, the slower the curing. When the deep part also needs to be cured rapidly, the gradual vulcanization method of layered irrigation can be adopted, and some rubber can be added at a time, etc. after vulcanization, the total vulcanization time can be reduced. Magnesium oxide can accelerate the vulcanization of a deep rubber.