Polypropylene (PP), also known as polypropylene, is a thermoplastic polymer with a wide range of uses. It is produced by the chain growth polymerization of the monomer propylene.

Polypropylene belongs to the class of polyolefins and is partially crystalline and non-polar. Its performance is similar to that of polyethylene, but it is slightly harder and has better heat resistance. It is a white, mechanically robust material with high chemical resistance. [1]

Bio-PP is the bio-based counterpart of polypropylene (PP). [2][3]

Polypropylene is the second most widely produced commodity plastic (after polyethylene). The global polypropylene market was valued at USD 126.03 billion in 2019. [4] Revenue is projected to exceed $145 billion by 2019. Sales of this material are expected to grow at an annual rate of 5.8% through 2021.

Phillips petrochemists J. Paul Hogan and Robert Banks first demonstrated the polymerization of propylene in 1951. [6] Giulio Natta and Karl Rehn March 1954 for the discovery of stereoselective to isotactic polymerization. [7] This pioneering discovery led to the large-scale commercial production of isotactic polypropylene by the Italian company Montecatini beginning in 1957. [8] Syndiotactic polypropylene was also first synthesized by Natta.

Polypropylene is similar to polyethylene in many respects, especially in solution behavior and electrical properties. Although the chemical resistance is reduced, the methyl group improves the mechanical properties and heat resistance. [9]: 19 The properties of polypropylene depend on molecular weight and molecular weight distribution, crystallinity, type and ratio of comonomers (if used), and isotacticity. [9] For example, in isotactic polypropylene, the methyl groups are oriented on one side of the carbon backbone. This alignment creates a greater degree of crystallinity and results in a stiffer material that is more resistant to creep than atactic polypropylene and polyethylene.