polipropylene

Polypropylene, commonly abbreviated PP, is a thermoplastic polymer in the polyolefin family. It is produced by addition polymerization of propylene, typically using Ziegler–Natta or metallocene catalysts. Commercial polypropylene is predominantly isotactic, which yields a semi-crystalline material with a relatively high melting point and good heat resistance.

Key properties include a density of about 0.90 g/cm3, a melting temperature around 160–170°C, and a combination of stiffness, toughness, and chemical resistance. PP resists many acids and bases, has good electrical insulation, and exhibits excellent fatigue resistance. However, its impact strength decreases at low temperatures unless modified; copolymers and blends can improve toughness and clarity. Random ethylene–propylene copolymers have higher impact strength and better clarity than homopolymers.

PP is processed in various ways and exists in several grades: homopolymer, random copolymer, and impact-modified forms. It is widely processed by injection molding, extrusion (including film and sheet), and blow molding, making it suitable for containers, caps, fibers, films, and molded automotive and consumer parts.

Applications include packaging, such as rigid containers and caps, food and consumer product packaging films, textile fibers (carpets and upholstery), automotive components, and medical devices that require sterilization compatibility.

Environment and recycling: polypropylene is recyclable (often coded as resin #5). It is not biodegradable; its environmental impact depends on production, usage, and end-of-life management. Recycling streams convert PP into new containers, fibers, or automotive parts.