Polypropylene(PP) is a polymer obtained by the addition of propylene. The synthesis of PP was developed from 1960s and was further developed in the 1980s. Isotactic polypropylene was successful from the early 1960s due to the new catalysts for polymerisation developed by Ziegler and Natta in 1954.[5] It became an important plastic being used in many different forms and applications through a range of manufacturing processes. A large proportion of PP is used in fibres as constituents of fabrics, upholstery and carpets. Many industrial uses involve ropes, woven and non-woven fabrics and reinforcements. Since the 1980s the production, consumption and applications of this polymer have increased through the application of even more efficient catalysts and property enhancements and today PP is the most common fibre used all over the world. Polypropylene has stable chemical properties (not reactive at room temperature), good yield strength (50MPa), good insulation and flame retardancy, so it has been widely developed and applied in many fields such as machinery, medical treatment, food packaging, textile and so on. The production of polypropylene is based on propylene as raw material, through the polymerization reaction. Polypropylene is mainly used to make melt-blown nonwovens and spunbonded nonwovens, which are the core materials in mask production.Spunbonded non-woven fabric is in the polymer has been extruded, stretched and formed continuous filament, filament laid into a net, the net by its own bonding, thermal bonding, chemical bonding or mechanical reinforcement methods, so that the net into nonwoven fabric.The melt-blown cloth is produced by using an extruder to squeeze the melt out of the spinneret head and a flow of air to introduce the polymer melt into the fiber.

Processing

                                                 Figure 1: mechanism of chain growth polymerization

Application

Film material: polypropylene based non-woven fabric made by melt blown process, with many crisscross fibers laminated in any direction to form a protective

fabric that passes through the air but blocks most of the floating dust in the air. Melt blown fabric is the core material of filtration, protection and isolation products. It is the filter layer in the middle of the mask, which can filter bacteria and prevent bacteria from spreading.

Figure. 2  Film material

Injection molding products: including auto parts, medical devices, electrical protection devices, packaging materials, etc. Polypropylene is bent and folded into thermoplastic polypropylene material under certain conditions. Due to the properties of low density, convenient processing and high tensile strength, polypropylene material is widely used in various fields of parts.

Figure.3 Injection molding products 

Construction or other large-scale factory manufacturing plate: Polypropylene plays an important role in cooling processing and molding. Due to its excellent properties of tensile strength at room temperature and Young's modulus, polypropylene plastic is also used as the plate production of some construction companies or some special factories.

 Figure.4 Construction manufacturing plate