Polypropylene (PP) is propylene copolymer with a melting point of around 165°C. Polypropylene has the lowest specific density, 0.91 g/cm3, compared to other general-purpose thermoplastics. The main properties of this material are good heat resistance, hardness and chemical resistance. It can be used at temperatures of up to 135°C (when used in pipes, at temperatures of up to 100°C). It is not recommended to use it with oxidizing acids, detergents, low-boiling hydrocarbons, alcohols and some chlorinated organic solvents. Uncolored natural PP is destroyable under ultraviolet rays, and therefore it shall be pigmented or stabilized otherwise.
The main disadvantage of PP is its fragility (glass transition) at a temperature of around 0°C. In order to avoid this, polypropylene is usually copolymerized with ethylene.
Polypropylene is used in all main economic sectors: electronics, construction, automotive industry, mechanical engineering, transportation, instrumentation, medicine, etc. Due to a large number of polypropylene-based materials, environmental friendliness, ease of processing and recycling, PP puts high-impact polystyrene, ABS plastics and PVC out of the market. Polypropylene is used most widely in the production of packaging, fibers, anticorrosion materials, automotive industry, electronics and medicine. Due to its performance and consumer qualities, polypropylene and its copolymers are very popular (with more than a 20% share in the world production), that is the second most popular after polyethylene.
Recycling is an important segment of the market of polypropylene materials. The method of extrusion of purified waste is commonly used for this purpose, with its subsequent crushing. A recycled granular material suitable for the production of different items is a result.
Lots of new varieties of polypropylene, with properties similar to rubber, have recently appeared in the market of polymer materials, which helps find new areas of its application.