Silicone oil has many special properties:










Good heat resistance










The main chain of polysiloxane molecule is composed of -si-o-si-bond, which is similar to the structure of inorganic polymer and has high bond energy, so it has excellent heat resistance.










· good oxidation stability and weather resistance










Good electrical insulation










Silicon oil has good dielectric properties, and its electrical properties change little with temperature and cycle number. The dielectric constant decreases with the increase of temperature, but the change is little. The power factor of silicone oil is low and increases with the increase of temperature, but there is no rule with the change of frequency. Volume resistivity decreases with temperature.










· good 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 arranged outwards to prevent water molecules from entering the inside and play a hydrophobic role. The interfacial tension of silicone oil to water is about 42 dyne/cm. When it diffuses over the glass, it forms a contact Angle of about 103oC due to its water repellency, comparable to paraffin.














The viscosity temperature coefficient is small










The viscosity of silicone oil is low and varies little with temperature, which is related to the helical structure of silicone oil molecules. Silicone oil is a kind of oil which has the best viscosity-temperature characteristic among all kinds of liquid lubricants.










· high compression resistance










Due to the helical structure and large intermolecular distance, silicone oil has high compression resistance. With this characteristic of silicone oil, it can be used as a liquid spring.










· low surface tension










Low surface tension is characteristic of silicone oil. Low surface tension indicates high surface activity. Therefore, silicone oil has excellent defoaming and anti-foaming performance, isolation performance and lubrication performance from other substances.










Non-toxic, tasteless and physiological inertia










From a physiological point of view, siloxane polymers are among the most inactive compounds known. Dimethyl silicone oil is inert to living things and has no rejection reaction with animal body. Therefore, they have been widely used in the departments of surgery and internal medicine, medicine, food and cosmetics.










· good lubrication










Silicone oil has many excellent properties as a lubricant, such as high flash point, low freezing point, thermal stability, viscosity with temperature change small, non-corrosive metal and rubber, plastic, paint, organic paint film without adverse effects and low surface tension, easy to spread on the metal surface and other characteristics. In order to improve the lubricity of silicone oil steel to steel, a lubricating additive which can be miscible in silicone oil can be added. The lubrication property of silicone oil can be greatly improved by introducing chlorophenyl group into siloxane chain or replacing dimethyl group with trifluoropropyl methyl group.










Chemical properties










Silicone oil is inert because the si-c bond is stable. But strong oxidants are easy to work with, especially at high temperatures. Silicone oil reacts violently with chlorine gas, especially methyl silicone oil. Sometimes there are explosive reactions. The si-o bond is easily broken by a strong base or acid. Concentrated sulfuric acid reacts quickly at low temperatures, breaking siloxane chains and attaching them. In this respect, silicone oil with high alkane groups and phenyl groups is relatively stable, but concentrated sulfuric acid will break the phenyl benzene-silicon bond and release benzene.