PP board, also known as polypropylene (PP) board (PP pure board, modified PP board, reinforced PP board, PP welding rod), is a semi-crystalline material. It is harder and has a higher melting point than PE. Since homopolymer PP is very brittle at temperatures above 0 °C, many commercial PP materials are random copolymers with 1 to 4% ethylene added or pinched copolymers with higher ethylene content.