Keywords: viscous liquid, liquid, temperature, Polyethylene glycol, water, freezing point,

Polyethylene glycol (PEG) chemical properties
　　Depending on the molecular weight, the properties vary from colorless odorless viscous liquid to waxy solid. Molecular weight 200~600 is liquid at room temperature, molecular weight above 600 gradually become semi-solid, with different average molecular weight, properties are also different. From colorless odorless viscous liquid to waxy solid. As the molecular weight increases, its moisture absorption capacity decreases accordingly. This product is soluble in water, ethanol and many other organic solvents. Low vapor pressure, stable to heat, acid and alkali. It does not work with many chemicals. Good moisture absorption, lubricity, adhesion. Non-toxic, non-irritating. The average molecular weight is 300,n = 5~5.75, melting point -15~8 ℃, relative density 1.124~1.130. The average molecular weight is 600,n = 12~13, melting point 20~25 ℃, flash point 246 ℃, relative density 1.13(20 ℃). The average molecular weight is 4000,n = 70~85, melting point 53~56.
　　Under normal conditions, polyethylene glycol is very stable, but it can interact with oxygen in the air at 120°C or higher. In an inert atmosphere (such as nitrogen and carbon dioxide), it will not change even if it is heated to 200~240 ℃, and thermal cracking will occur when the temperature rises to 300 ℃. Adding antioxidants, such as phenothiazine with a mass fraction of 0.25%~ 0.5%, can improve its chemical stability. Any of its decomposition products are volatile and do not form crust or slimy precipitates.
　　Polyethylene glycol is a polymer of ethylene oxide hydrolysis product, which is non-toxic and non-irritating, and is widely used in various pharmaceutical preparations. Low molecular weight polyethylene glycol is relatively toxic, and on the whole, the toxicity of 2 alcohols is quite low. Topical application of polyethylene glycol, especially mucosal administration, can result in irritant pain. In topical lotion, this product can increase the flexibility of the skin and has a moisturizing effect similar to glycerin. Diarrhea can occur when large doses are taken orally. In the injection, the maximum 300 concentration of polyethylene glycol is about 30%(V/V), and hemolysis can occur when the concentration is greater than 40%(V/V).
　　Polyethylene oxide and water addition polymer. The molecular weight below 700 is colorless, odorless and non-volatile viscous liquid at 20 ℃, with slight water absorption. Those with a molecular weight between 700 and 900 are semi-solids. The molecular weight of 1000 and above is light white waxy solid or flake paraffin or flow powder. Miscible in water, soluble in many organic solvents, such as alcohols, ketones, chloroform, glycerides and aromatic hydrocarbons; insoluble in most aliphatic hydrocarbons and ether.
　　With the increase of molecular weight, its water solubility, vapor pressure, water absorption and solubility of organic solvents decrease accordingly, while the freezing point, relative density, flash point and viscosity increase accordingly. Stable against heat, does not work with many chemicals, does not hydrolyze.

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