What Is Methyl Silicone Oil?
Generally, methyl silicone oil is colorless, tasteless, non-toxic and non-volatile liquid. It is insoluble in water, methanol or ethylene glycol. It can be intersoluble with benzene, dimethyl ether, carbon tetrachloride or kerosene. It is slightly soluble in acetone, dioxan, ethanol and butanol. As for methyl silicone oil, because the intermolecular force is small, the molecular chain is spiral, and the organic groups can be freely rotated, it has excellent characteristics of spreading performance, lubricity, high and low temperature resistance, weather resistance, radiation resistance, high flash point, low surface tension and physiological inertia, etc. It is widely applied in the industries of daily chemical, machinery, electric, textile, coating, medicine and food, etc.
The Characteristics of Methyl Silicone Oil
Methyl silicone oil has much special performance.
■ Good heat resistance
In the silicone oil molecular, the main chain is composed of -Si-O-Si-, which has similar structure with inorganic polymer and has high bond energy. So it has excellent performance of heat resistance.
■ Good oxidation resistance and weather resistance
■ Good electrical insulating performance
Silicone oil has excellent dielectric properties. With the change of temperature and cycle number, its electrical characteristic changes little. Dielectric constant decreases as temperature increases, but the change is very small. The power factor of silicone oil is low and increases with temperature rises, but there are no rules for frequency. The volume resistivity decreases with increasing temperature.
■ Excellent hydrophobicity
Although the main chain of silicone oil is composed of polar bond, Si-O, the non-polar alkyl groups on the side chain are oriented outward to prevent water molecules from entering the interior and play a hydrophobic role. The interfacial tension between silicone oil and water is about 42 dynes/ cm. When diffusing over glass, due to its water repellency, silicone oil can form a contact angle of about 103°, comparable to paraffin wax.
■ Small viscosity-temperature coefficient
The viscosity of silicone oil is low and it changes little with temperature. It is related with the spiral structure of silicone oil molecules. Silicone oil is the one with the best viscosity-temperature characteristic among all kinds of liquid lubricants. This characteristic makes great sense to damping equipment.
■ High resistance to compression
Because of its spiral structure and large intermolecular distance, silicone oil has high compressibility resistance. Using this characteristic of silicone oil, it can be used as a liquid spring. Compared with mechanical spring, the volume can be greatly reduced.
■ Low surface tension
Low surface tension is the characteristic of silicone oil. Low surface tension indicates high surface activity. Hence, silicone oil has excellent defoaming and antifoaming performance, isolation performance with other substances and lubricating performance.
■ Non-toxic, non-volatile and physiological inertia
From the physiological point of view, siloxane polymer is one of the least active compounds known. Dimethyl silicone oil is inert to organisms and has no rejection reaction with animals. So it has been widely applied in surgery department and internal medicine department, medicine, food and cosmetics, etc.
■ Good lubricity
Silicone oil has many excellent properties as a lubricant, such as high flash point, low freezing point, thermal stability, small viscosity change with temperature, no corrosion of metal and no negative influence on rubber, plastic, paint and organic paint film, low surface tension, easy to spread on the metal surface and so on. In order to improve the steel to steel lubricity of silicone oil, lubricating additives that can be mixed with silicone oil can be added. The lubricating properties of silicone oil can be greatly improved by introducing chlorophenyl group into the siloxan chain or replacing dimethyl group with trifluoropropyl methyl group.
Post time: Aug-09-2021