The main functional uses of silicone rubber
Silicone dioxide (Silicon dioxide) alias: Silicone rubber is a highly active adsorption material, an amorphous substance, and its chemical formula is mSiO2·nH2O.It is insoluble in water and any solvent, non-toxic, tasteless, chemically stable, and does not react with any substances except strong alkali and hydrofluoric acid.Various types of silica gel form different microporous structures due to different manufacturing methods.The chemical composition and physical structure of silica gel determine that it has many characteristics that are difficult to replace with other similar materials: high adsorption performance, good thermal stability, stable chemical properties, high mechanical strength, etc.Silica gel is divided into macroporous silica gel, coarse pore silica gel, B-type silica gel and fine pore silica gel according to its pore size.
Silicone
The basic structural unit of organic silica gel products is composed of silicon-oxygen chain links, and the side chains are connected to various other organic groups through silicon atoms.Therefore, the structure of silicone products contains both "organic groups" and "inorganic structures". This special composition and molecular structure allows it to combine the characteristics of organic substances and the functions of inorganic substances.Compared with other polymer materials, the outstanding properties of silicone products are:
1. Temperature resistance characteristics
Silicone products have a main chain structure of silicon-oxygen (Si-O) bonds. The bond energy of the CC bond is 82.6 kcal/g. The bond energy of the Si-O bond in organic silicon is 121 kcal/g. Molecules, so silicone products have high thermal stability, and the chemical bonds of molecules will not break or decompose under high temperatures (or radiation exposure).Silicone is not only resistant to high temperatures, but also to low temperatures and can be used in a wide temperature range.Whether it is chemical properties or physical and mechanical properties, the changes with temperature are very small.
2. Weather resistance
The main chain of silicone products is -Si-O-, and there are no double bonds, so it is not easily decomposed by ultraviolet light and ozone.Silicone has better thermal stability, radiation resistance and weather resistance than other polymer materials.The service life of silicone in the natural environment can reach decades.
3. Electrical insulation performance
Silicone products all have good electrical insulation properties. Their dielectric loss, voltage resistance, arc resistance, corona resistance, volume resistivity and surface resistivity are among the best among insulating materials, and their electrical properties are affected by temperature and frequency. The impact is very small.Therefore, they are stable electrical insulating materials and are widely used in the electronic and electrical industries.In addition to excellent heat resistance, silicone also has excellent water repellency, which guarantees the high reliability of electrical equipment when used in wet conditions.
4.Physiological inertia
Silicones are one of the known inactive compounds.They are very resistant to biological aging, have no rejection reaction with animal bodies, and have good anticoagulant properties.
5. Low surface tension and low surface energy
The main chain of silicone is very flexible, and its intermolecular force is much weaker than that of hydrocarbons. Therefore, it has lower viscosity, weaker surface tension, smaller surface energy, and stronger film-forming ability than hydrocarbons of the same molecular weight.This low surface tension and low surface energy are the main reasons why it has many applications: hydrophobic, defoaming, foam stabilization, anti-sticking, lubrication, glazing and other excellent properties.
Uses of silicone
Because silicone has the above-mentioned excellent properties, its application range is very wide.It is not only used as a special material in aviation, cutting-edge technology, and military technology sectors, but also in various sectors of the national economy. Its application scope has expanded to: construction, electronics and electrical, textiles, automobiles, machinery, leather and papermaking, chemical and light industry, Metal and paint, medicine and medical treatment, etc.
Classification of silicone
Silicones are mainly divided into three categories: silicone rubber, silicone resin, and silicone oil.
Silicone rubber classification
Silicone rubber is mainly divided into room temperature vulcanized silicone rubber and high temperature vulcanized silicone rubber.
Introduction to room temperature vulcanized silicone rubber and its classification
Room temperature vulcanized silicone rubber (RTV) is a new type of silicone elastomer that came out in the 1960s. The distinctive feature of this rubber is that it can be cured in place at room temperature without heating or pressing, making it extremely easy to use.Therefore, it quickly became an important part of the entire silicone products as soon as it came out.
Room temperature vulcanized silicone rubber is now widely used as adhesives, sealants, protective coatings, potting and molding materials, and has its uses in various industries.
Room temperature vulcanized silicone rubber can be divided into single-component and two-component room temperature vulcanized silicone rubber according to its packaging method. According to the vulcanization mechanism, it can be divided into condensation type and addition type.Therefore, room temperature vulcanized silicone rubber can be divided into three major types according to different compositions, vulcanization mechanisms and usage processes, namely single-component room temperature vulcanized silicone rubber, two-component condensation type room temperature vulcanized silicone rubber and two-component addition type room temperature vulcanized silicone rubber. .Each of these three series of room temperature vulcanized silicone rubber has its own characteristics: the advantage of one-component room temperature vulcanized silicone rubber is that it is easy to use, but the deep curing speed is difficult; the advantage of two-component room temperature vulcanized silicone rubber is that it does not release heat during curing. The shrinkage rate is very small, there is no expansion, and there is no internal stress. The curing can be carried out both internally and on the surface at the same time, and can be deeply vulcanized. The vulcanization time of addition type room temperature vulcanized silicone rubber mainly depends on the temperature. Therefore, the vulcanization speed can be controlled by adjusting the temperature. .
Among the many synthetic rubbers, silicone rubber is the best.It is odorless and non-toxic, not afraid of high temperatures and resistant to severe cold. It is "calm" and "face unchanged" at 300 degrees Celsius and minus 90 degrees Celsius, without losing its original strength and elasticity.Silicone rubber also has good electrical insulation, oxygen resistance and aging resistance, light resistance and aging resistance, mildew resistance, chemical stability, etc.