Ethylene oxide (EO), also known as ethylene oxide, has a molecular formula of C2H4O and a chemical formula of ch2-ch2 with a molecular weight of 44.05. This small and unstable ternary ring structure of EO makes it highly chemically active and penetrating. At 4 ℃, the specific gravity is 0.884, and the boiling point is 10.8 ℃. Therefore, EO is gaseous at room temperature and atmospheric pressure, heavier than air, with a density of 1.52g/cm3. When volatilized, it has an aromatic ether flavor, and the threshold value of smell is 500-700ppm. EO liquid is colorless and transparent, and can be mixed with any proportion of water, and also soluble in common organic solvents or oils.

Ethylene oxide has a large vapor pressure, so it has a strong penetration to sterilized articles. It can penetrate through micropores to reach the deep part of the articles. It is precisely because of this deep penetration of EO that it has a good sterilization ability. In industrial production, the method of packaging before sterilization is widely used.

The chemical properties of ethylene oxide are active. Contact with catalyst can cause polymerization, which is accelerated with the increase of temperature, pressure and water content. If the reaction takes place in the cylinder, the color of ethylene oxide will be deepened, the yellow viscous substance will be produced, the pipeline will be blocked, and the sterilization effect will be affected. Therefore, the ethylene oxide cylinder should be stored in shade and its validity period should be specified.

Ethylene oxide can also be mixed with inert gas (such as carbon dioxide CO2, nitrogen N2) to synthesize mixed gas. The commonly used proportion of ethylene oxide is 10%, 20%, 30%. The mixed gas has good safety and better penetration during sterilization, which is beneficial to the sterilization effect. It should be noted that due to various reasons, there are quite a number of disposable sterile medical device manufacturers in China at present. Pure ethylene oxide is still used for sterilization before leaving the factory. With the improvement of product packaging quality and technological progress, with the increase of mixed gas supplier's output, cost reduction and increase of supply network, safe and effective mixed gas is used to replace pure ring in industrial sterilization Oxyethane will be the development trend.