Room temperature vulcanized silicone rubber (RTV) is a new type of silicone elastomer developed in the 1960s. The most remarkable feature of RTV is that it can be cured in place at room temperature without heating or pressing, and it is extremely convenient to use. Therefore, as soon as it came out, it became an important part of the whole silicone products. Now RTV silicone rubber has been widely used as adhesives, sealants, protective coatings, potting and molding materials in all walks of life.


Room temperature vulcanized silicone rubber is known as liquid silicone rubber because of its low molecular weight. Its physical form is usually flowable fluid or viscous paste, and its viscosity is between 100 and 1000000 centistokes. According to the requirements of use, the rubber compound before vulcanization can be mixed into automatic leveling filling material or non flowing putty which can be applied. The filler used in RTV silicone rubber is similar to that used in HTV silicone rubber. The vulcanizate is reinforced with silica, so that the tensile strength of the vulcanizate is 10-60 kggcm2. Adding different additives can make the compound have different specific gravity, hardness, strength, fluidity and thixotropy, and make the vulcanizate have various special properties such as flame retardant, electric conductivity, thermal conductivity and ablation resistance.


RTV silicone rubber can be divided into single component and two-component RTV silicone rubber according to its packaging method, and can be divided into condensation type and addition type according to its curing mechanism. Therefore, RTV silicone rubber can be divided into three types according to composition, vulcanization mechanism and application process, namely one component RTV silicone rubber, two-component condensation RTV silicone rubber and two-component addition RTV silicone rubber.


The raw rubber of one component and two-component RTV silicone rubber is the same α,ω- Dihydroxypolysiloxane; The addition room temperature vulcanized silicone rubber is a polysiloxane containing alkenyl and hydrogen side groups (or end groups). Because it can achieve good curing effect at a temperature slightly higher than room temperature (50-150 ℃), it is also called low temperature vulcanized silicone rubber (LTV).


The three series of RTV silicone rubber have their own advantages and disadvantages: one component RTV silicone rubber is easy to use, but it is difficult to cure in depth; The advantages of two-component RTV silicone rubber are no exothermic during curing, small shrinkage, no expansion and no internal stress. The curing can be carried out inside and on the surface at the same time and can be deep vulcanized; The curing time of addition room temperature vulcanized silicone rubber mainly depends on the temperature, so the curing speed can be controlled by adjusting the temperature.