Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene.
Polypropylene belongs to the group of polyolefins and is partially crystalline and non-polar. Its properties are similar to polyethylene, but it is slightly harder and more heat-resistant. It is a white, mechanically rugged material and has a high chemical resistance.
Bio-PP is the bio-based counterpart of polypropylene (PP).
Polypropylene is the second-most widely produced commodity plastic (after polyethylene).
The density of PP is between 0.895 and 0.93 g/cm3. Therefore, PP is the commodity plastic with the lowest density. With lower density, moldings parts with lower weight and more parts of a certain mass of plastic can be produced. Unlike polyethylene, crystalline and amorphous regions differ only slightly in their density. However, the density of polyethylene can significantly change with fillers.
The Young’s modulus of PP is between 1300 and 1800 N/mm².
Polypropylene is normally tough and flexible, especially when copolymerized with ethylene. This allows polypropylene to be used as an engineering plastic, competing with materials such as acrylonitrile butadiene styrene (ABS). Polypropylene is reasonably economical.
Polypropylene has good resistance to fatigue.
AKA “The chemically-resistant plastic”
HISTORY
Phillips Petroleum chemists J. Paul Hogan and Robert Banks first demonstrated the polymerization of propylene in 1951. The stereoselective polymerization to the isotactic was discovered by Giulio Natta and Karl Rehn in March 1954. This pioneering discovery led to large-scale commercial production of isotactic polypropylene by the Italian firm Montecatini from 1957 onwards. Syndiotactic polypropylene was also first synthesized by Natta.
SAFETY
Same as LDPE, PP is safe for food and drink use because it does not transmit chemicals into the things humans consume due to its relatively high melting point(171°C). It is also recyclable giving every reason why it’s better to use this. The advocacy organization Environmental Working Group classifies PP as of low to moderate hazard.
Credits: Polypropylene – Wikipedia and Get to Know the 7 Types of Plastic- Plastics 101 | by The Physics Society | Medium
