Basic properties and uses of methyl silicone oil
Polydimethylsiloxane
What is methyl silicone oil: Methyl silicone oil is generally colorless, odorless, non-toxic, non-volatile liquid, insoluble in water, methanol, ethylene glycol, and can be mutually soluble with benzene, dimethyl ether, carbon tetrachloride or kerosene, slightly soluble in acetone, dioxane, ethanol and butanol. Methyl silicone oil is a linear polyorganosiloxane with Si-O-Si as the main chain, 2 methyl groups connected to Si, and trimethylsiloxane capped, which is liquid at room temperature and has the following structural formula
1. Good heat resistance
Silicone oil molecules due to the main chain is composed of -Si-O-Si-Bond, with a similar structure to the inorganic polymer, the bond energy is very high, so it has excellent heat resistance.
2. Good oxidation stability and weathering resistance
3. Good electrical insulation
Silicone oil has good dielectric properties, with the temperature and the number of waves, its electrical properties change very little. The dielectric constant decreases with increasing temperature, but the change is very small. The power factor of silicone oil is low and increases with temperature rise, but there is no rule with frequency change. Volume resistivity decreases with temperature rise.
4. Good hydrophobicity
Although the main chain of silicone oil consists of polar bonds Si-O, but because of the side chain of the non-polar base of alkyl directed outward arrangement, preventing water molecules from entering the interior, playing a hydrophobic role. Silicone oil to water interfacial tension of about 42 dyne / cm, when diffused in the glass above, due to the water repellency of silicone oil, the formation of about 103 ° contact angle, comparable to paraffin.
5. Small coefficient of viscosity and temperature
Silicone oil has a low viscosity and small change with temperature, which is related to the spiral structure of silicone oil molecules. Silicone oil is a variety of liquid lubricants with the best viscosity and temperature characteristics of a class of oil, silicone oil, this characteristic of the damping equipment is very meaningful.
6. High compression resistance
Silicone oil molecules have high compression resistance due to their helical structure and large intermolecular distances. Using this characteristic of silicone oil, it can be used as a liquid spring, and compared with mechanical springs, the volume can be greatly reduced.
7. Low surface tension
Low surface tension is a characteristic of silicone oil. Low surface tension means high surface activity, so silicone oil has excellent anti-foaming and anti-foaming properties, isolation from other substances and lubricating properties.
8. Non-toxic, odorless and physiologically inert
From a physiological point of view, silicone polymers are one of the most inactive compounds known. Dimethicones are biologically inert and have no rejection with the animal body. Therefore, they have been widely used in sectors such as surgery and internal medicine, pharmaceuticals, food and cosmetics.
9. Good lubrication
Silicone oil has many excellent properties as a lubricant, such as high flash point, low freezing point, heat stability, viscosity with temperature change is small, does not corrode the metal as well as rubber, plastics, paints, organic varnish film has no adverse effects and low surface tension, easy to spread on the surface of the metal and other characteristics. In order to improve the steel-to-steel lubricity of silicone oil, can be added to the lubricity additives that can be miscible with silicone oil. The introduction of chlorophenyl group on the silicone chain or the replacement of dimethyl with trifluoropropyl methyl can greatly improve the lubricating properties of silicone oil.
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