Polypropylene is a polymer formed by addition polymerization of propylene. It is a white waxy substance with a transparent and light appearance. The density is 0.89 ~ 0.9 1g/cm3, flammable, the melting point is 165℃, it softens around 155℃, and the service temperature range is -30 ~ 140℃. It can resist the corrosion of acid, alkali, salt solution and various organic solvents below 80℃, and can be decomposed under high temperature and oxidation.

Polypropylene is widely used in the production of clothing, blankets and other fiber products, medical equipment, automobiles, bicycles, parts, transportation pipelines, chemical containers and so on. It is also used for the packaging of food and medicine.

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According to the spatial position of methyl (-CH3) in polypropylene molecules, polypropylene can be divided into three types: isotactic, syndiotactic and random. According to the polymerization process, isotactic polypropylene can be divided into several methods, such as slurry method, bulk method, solution method and gas phase method. According to the purpose, it can be divided into flat yarn (narrow band), fiber, film, extrusion, blow molding, injection molding and other grades, and according to the monomer type, it can be divided into homopolymer polypropylene and polypropylene.

The consumption of polypropylene in China is increasing at an average annual rate of 10%, which greatly exceeds the world average growth level. China is the second largest consumer of synthetic resin, second only to polyethylene.