The difference between silicone and silicone rubber
Silica gel is a collection of synthetic rubber chemical analysis called silica. Because of its special chemical properties, it has its figure in various fields. Rubber is a completely amorphous polymer, and its glass transition temperature (Tg) is low, the molecular weight is often very large, greater than hundreds of thousands.
1. Silica gel, also known as silicic acid gel, is a granular and porous silica hydrate, which is an amorphous substance with a transparent or milky white appearance. It is made of sodium silicate with acid and washed and dried. It has stable chemical properties. Does not burn.
2. Silica gel is a kind of highly active adsorbent material, mainly used as desiccant and adsorbent in column chromatography and thin layer chromatography. Generally speaking, it can be divided into two categories: organic silica gel and inorganic silica gel.
3. Rubber is an elastic polymer that can be obtained from the sap of some plants, or it can be artificial. According to different manufacturing methods, rubber can be divided into synthetic rubber and natural rubber. It has quite a few applications and products, such as tires and gaskets. Rubber cultivation is mainly concentrated in Southeast Asia, such as Thailand, Malaysia and Indonesia.
Silicone rubber characteristics classification
1. General type: It is composed of vinyl silicone rubber and reinforcing agent. The physical and mechanical properties of the vulcanizing machine are of medium strength. The tensile strength is 4.9～6.9MPa (5～7kgl/cm2), and the elongation is: 200～300% , Is the most widely used and most versatile rubber compound.
2. High-strength type (high tear resistance): use vinyl silicone rubber or low benzene silicone rubber, use gas-phase white carbon with high specific surface area or modified white carbon black as reinforcing agent, and add suitable Processing aids and special additives and other comprehensive coordination and improvement measures to improve the cross-linking structure (concentrated cross-linking) and tear strength, the tensile strength of this compound is 7.8 ~ 9.81MPA (80 ~ 100kgl/cm2), The elongation at break is 500% to 1000%, and the tear strength is 29.4 to 49KN/m.
3. High temperature resistant type: adopts vinyl silicone rubber or low phenyl silicone rubber. The type of reinforcing agent and heat-resistant additives can be properly selected to produce high-temperature silicone rubber of 300～350℃.
4. Low temperature type: Low phenyl silicone rubber is mainly used, the brittleness temperature can reach -120℃, and the elasticity is not lost at -90℃.
5. Low compression permanent deformation type: using vinyl silicone rubber, with a special organic peroxide as a vulcanizing agent for vinyl. When the compression rate is 30%, the compression set after compression at 150°C for 24 to 72 hours is 7.0 to 15% (common silicone rubber is 20 to 30%).
6. Wire and cable type: mainly adopts vinyl silicone rubber, and uses gas-phase white carbon black with good electrical insulation as a reinforcing agent, and has good extrusion process performance.
7. Oil-resistant and solvent-resistant type: ammonia silicone rubber is mainly used, generally two types are used: general-purpose type and high-strength type.
8. Flame retardant.
9. Conductive type.
10. Heat shrinkable.
11. Two-stage vulcanization-free type: It adopts vinyl silicone rubber with higher vinyl content, and is made by adding special additives by controlling the PH value of raw rubber and compounding agent. (Handbook of Rubber Industry P544).
12. Sponge silicone rubber: Add nitroso compounds, azo and diazo compounds and other organic foaming agents to the vinyl silicone rubber species to produce sponges with uniform pores.