Organic silica gel
Silicone compounds refer to compounds containing Si-C bonds, and at least one organic group is directly connected to silicon atoms, and it is customary to often use those compounds that connect organic groups with silicon atoms through oxygen, sulfur, nitrogen, etc., as silicone compounds.
  Among them, polysiloxane composed of silico-oxygen bond (-Si-0-Si-) as the skeleton is the most numerous, the most deeply studied and the most widely used class of silicone compounds, accounting for more than 90% of the total amount.
  Silicone materials have a unique structure:
(1) Sufficient methyl groups on Si atoms shield the high energy polysiloxane main chain;
(2) C-H is non-polar, so that the intermolecular force is very weak;
(3) The Si-O bond length is long, and the SI-O-Si bond Angle is large.
(4) Si-O bond is a covalent bond with 50% ionic bond characteristics (covalent bond is directional, ionic bond is non-directional).
  Due to the unique structure of organosilicon, it combines the performance of inorganic materials and organic materials. It has the basic properties of low surface tension, small viscosity-temperature coefficient, high compressibility, high gas permeability, and excellent characteristics of high and low temperature resistance, electrical insulation, oxidation resistance stability, weather resistance, flame resistance, water repellency, corrosion resistance, non-toxic and tasteless, and physiological inertia. Widely used in aerospace, electronic and electrical, construction, transportation, chemical, textile, food, light industry, medical and other industries, of which silicone is mainly used in sealing, bonding, lubrication, coating, surface activity, release, defoaming, foam suppression, waterproof, moisture-proof, inert filling and so on.
  With the continuous growth of the number and variety of silicone, the application field has been expanded, forming a unique and important product system in the field of new chemical materials, and many varieties are irreplaceable and essential for other chemicals.
  Silicone materials according to their different forms, can be divided into: silane coupling agent (silicone chemical reagents), silicone oil (silicone grease, silicon emulsion, silicon surfactant), high temperature vulcanized silicone rubber, liquid silicone rubber, silicone resin, complex and so on.
  Silicone rubber
  Silicone rubber is a straight chain of high molecular weight polysiloxane, molecular weight is generally more than 150,000, its structure is similar to silicone oil.
  According to the organic groups linked to silicon atoms, silicone rubber has dimethyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl silicone rubber, fluorine silicone rubber, nitrile silicone rubber, ethyl silicone rubber and many other varieties.
According to its vulcanization method, silicone rubber can be divided into high temperature vulcanization (hot vulcanization) silicone rubber and room temperature vulcanization (including low temperature vulcanization) silicone rubber two categories.
  No matter which type of silicone rubber, there is no exothermic phenomenon when vulcanized.
  High temperature vulcanized silicone rubber is a high molecular weight polysiloxane (molecular weight is generally 400,000 to 800,000), room temperature vulcanized silicone rubber is generally low molecular weight (30,000 to 60,000), at both ends of the molecular chain (sometimes also in the middle) each with one or two functional groups, under certain conditions (moisture in the air or appropriate catalyst), these functional groups can react. Thus, high molecular weight crosslinked structures are formed.
  Room temperature vulcanized silicone rubber can be divided into condensation type and addition molding according to its vulcanization mechanism. According to its packaging can be divided into two components and single components of two types.
  The nature of the silicon-oxygen bond that forms the main chain of silicone rubber determines that silicone rubber has the advantages that natural rubber and other rubber do not have, it has the widest operating temperature range (-100 ~ 350oC), excellent high and low temperature resistance, in addition, it also has excellent thermal stability, electrical insulation, weather resistance, ozone resistance, permeability, high transparency, tear strength, and so on. Excellent heat dissipation and excellent adhesion, fluidity and release, some special silicone rubber also has excellent oil resistance, solvent resistance, radiation resistance and use at ultra-low temperatures and other characteristics.
  In the use of temperature range, silicone rubber can not only maintain a certain softness, resilience and surface hardness, mechanical properties are not significantly changed, and can resist long-term thermal aging.
  Due to the special properties of silicone rubber, it can be used for molding high voltage edge and other electronic components, so that the adhesive has excellent leakage resistance and excellent demoulding property.
  Used in the production of TV sets, computers, copiers, etc., with good heat dissipation and insulation properties.
  It is also used as a molding gasket requiring weather resistance and durability, a packaging material for electronic parts, and a protective material for automotive electrical parts.
  Silicone rubber can be used for the construction and repair of houses, joint sealing of highways and caulking sealing of reservoirs and Bridges. Silicone rubber can also be used for strong adhesion, weathering resistance, alkali resistance, water resistance coatings.
  Because of the high temperature resistance of silicone rubber, it is used in the production of automobile parts.
  In addition, there are special uses of silicone rubber, such as conductive silicone rubber, medical silicone rubber, foam silicone rubber, molding silicone rubber, heat shrinkable silicone rubber and so on.