The meaning and characteristics of silica gel2021-01-06
Silica gel is a highly active adsorption material, which is an amorphous material. The position where the temperature continues to rise during the melting process is in an amorphous state
It is mainly composed of silicon dioxide, and also contains polysiloxane, silicone oil, coupling agent and fillers.
Because of the characteristics of silica gel, it can be insoluble in water and any solvents, is non-toxic and tasteless, and has stable chemical structure properties. It does not react with any other substances except strong alkali and hydrofluoric acid.
According to different manufacturing methods, silica gel can form different microporous structures, so there are different types of silica gel.
The chemical composition and physical structure of silica gel determine that silica gel has many characteristics that are difficult to replace: high adsorption performance, good thermal stability, stable chemical properties, and high mechanical strength. feature:
1. High and low temperature resistance performance:
Due to its unique molecular structure, silica gel has high thermal stability. Ordinary silica gel has a service life of up to 20 years at 120 ° c. It has good spiral molecular structure flexibility and low embrittlement temperature. It can reach -80 ° c to -115 ° by changing the molecular structure of polysiloxane c Low temperature working requirements.
2. Chemical resistance:
After being treated with volatile oils or polar solvents, silica gel can quickly restore its own properties, and can avoid softening and swelling, so it has excellent chemical resistance and rarely changes in volume.
3. Low surface activity and physiological inertia:
As a semi-inorganic polymer composite material, silica gel is a non-active compound. Through a special modification technology, it can be developed to achieve the design of fire retardant, anti-aging performance. Combined with the enterprise factory vulcanization, it can simultaneously achieve the improvement of green ecology and environmental protection. It is non-toxic and tasteless, basically harmless to the environment and human body. Due to the flexibility of the molecular chain of silica gel, it also has its own excellent characteristics such as good lubrication, anti-sticking, hydrophobic and defoaming.
4. Compression resistance:
Whether in the harsh environment of high temperature 250℃ or low temperature -60℃, silica gel has good compression resistance, can maintain a good stable state, and can prepare higher products according to market demand.
Since silica gel has no double bond in its main chain, it is not easily reduced by ozone, ultraviolet rays, etc., so it has good radiation resistance, can be used outdoors for decades, and can maintain good performance.
6. Air permeability:
Silica gel molecules have both inorganic and organic structures, a long distance between atoms and a large degree of freedom, so they have good solubility in gas, thereby obtaining excellent gas permeability and easily permeating gas molecules. It can be used in agricultural production, medical organs and other fields.