Polypropylene (PP) is a semicrystalline thermoplastic polyolefin produced through the catalytic polymerization of propylene monomer (CH₂=CH–CH₃), characterized by a linear hydrocarbon backbone with pendant methyl groups (–CH₃). The stereoregular arrangement of these groups, particularly in isotactic Polypropylene, facilitates crystalline structure formation, governing stiffness, tensile strength, thermal resistance, and dimensional stability. With a density typically ranging from 0.90 to 0.91 g/cm³, PP is among the lightest commercially produced commodity plastics. Its nonpolar molecular structure provides resistance to numerous aqueous chemicals and favorable electrical insulation properties, although performance varies with temperature, chemical exposure, and polymer formulation. Commercial PP resins are primarily classified into PP homopolymer and PP copolymer, with the latter comprising random and impact copolymer grades engineered for distinct balances of rigidity, transparency, impact toughness, and processing characteristics.

PP Grades