There are two main types of polypropylene available: homopolymers and copolymers. The copolymers are further divided into block copolymers and random copolymers. Each category fits certain applications better than the others but often it doesn’t matter which one is used.
Homopolymer polypropylene can be referred to as the default state of the polypropylene material and is a general-purpose grade.
Block copolymer polypropylene has co-monomer units arranged in blocks (that is, in a regular pattern) and contain anywhere between 5% to 15% ethylene. Ethylene improves certain properties, like impact resistance; other additives enhance other properties.
Random co-polymer polypropylene – as opposed to block copolymer polypropylene – has the co-monomer units arranged in irregular or random patterns along the polypropylene molecule. They are usually incorporated with anywhere between 1% to 7% ethylene and are selected for applications where a more malleable, clearer product is desired.
