Polypropylene — PP Unfilled

Polypropylene, also known as PP, is among the most economical thermoplastic polymer today. However, it has the lowest density among commodity plastics, making it lighter in weight. 
PP can be used as an engineering polymer as it is usually tough and flexible. Therefore, it has become a good competitor of materials such as ABS.
PP with a higher melt-flow index fills the plastic mould more efficiently during the injection moulding. However, as the melt flow increases, some physical properties, like impact strength, will decrease.