RTV silicones
RTV silicones are a type of silicone sealant that has a single-component system and dries at room temperature (room temperature vulcanizing). These silicones have a wide viscosity range; RTVs contain a combination of organic and inorganic materials, making it one of the most stable organic adhesive products on the market. These adhesives and sealants are resistant to high temperatures and are very flexible compared to other industrial adhesives.
RTV silicones use water and a drying agent to form an adhesive or coating. When these materials combine during crosslinking, a chemical process occurs. Depending on what agent you are using, this chemical process may be in the form of an acetoxy, an amine, or a neutral methyl and ethyl alkoxy or oxime. The drying agent will determine the final properties of your adhesive. The relative humidity and temperature of the surrounding environment will directly determine the drying rate, in general, RTV silicone will dry within 72 hours, although the adhesive may still gain strength up to two weeks after curing.
These adhesives have several characteristics; Their only limitation is that they cannot be painted with water-based paint. These adhesives are very flexible (depending on temperature) and have a wide operating temperature range. They are resistant to harsh weather conditions, moisture and fungus and mold, and also have excellent electrical properties. RTV silicone has a lifespan of 40 years and has a high degree of tensile strength; Even at low temperature, these adhesives have high UV resistance and excellent thermal stability.
Fillers such as citric acid can provide faster drying times, while oxides and nitrides can provide better thermal conductivity.
Usually, RTVs include acetoxy-cured silicone and neutral-cured silicone (oxime). Acetoxy silicones have a relatively fast drying speed and a short tack-free time that provides good quality adhesion, although they are corrosive to metals. This type of RTV silicone releases acid and will smell like vinegar.
On the other hand, oxime or silicone with neutral curing is non-corrosive and has excellent oil properties and temperature resistance. This type of silicone produces a neutral product that takes longer to dry and has a longer tack-free.