PP Polypropylene Sheets - PP sheets are a semi-crystalline material. They are harder than PE and have a higher melting point. Due to the brittleness of homopolymer PP above 0°C, many commercial PP materials are modified by adding 1-4% random copolymer with ethylene or block copolymers with higher ethylene content. Copolymer PP materials have lower heat deflection temperatures (100°C), lower transparency, lower luster, lower rigidity, but with greater impact strength. The strength of PP increases with the increase in ethylene content. The Vicat softening temperature of PP is 150°C. Due to higher crystallinity, the surface rigidity and scratch resistance of this material are excellent. PP does not have environmental stress cracking issues. Typically, PP is modified by adding glass fibers, metal additives, or thermoplastic rubber. The melt flow rate (MFR) of PP ranges from 1 to 40.