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. Homopolymer polypropylene is a strong and rigid plastic that is used in applications such as packaging, automotive parts, and toys. Random copolymer polypropylene is more flexible and has better transparency than homopolymer polypropylene, making it suitable for applications such as food packaging and medical devices. Block copolymer polypropylene is a combination of the two and is used in applications such as impact-resistant containers and automotive parts.