HDPE

HDPE, or high-density polyethylene, is a thermoplastic polymer produced from ethylene with a relatively linear structure and minimal branching. The limited branching allows tighter packing of chains, giving HDPE a higher density and greater stiffness than low-density polyethylene (LDPE). Typical densities range from about 0.941 to 0.965 g/cm³, and the resin exhibits strong chemical resistance, low moisture absorption, good impact strength, and good abrasion resistance. HDPE can be fabricated by extrusion, injection molding, blow molding, and other conventional plastic processing methods.

Production and grades are based on catalytic polymerization, using Ziegler-Natta or metallocene catalysts to minimize branching and achieve higher crystallinity. Melt flow rates vary across grades, enabling a spectrum of properties from rigid, high-strength resins to more flexible, impact-modified variants. HDPE is commonly divided into broad family groups for piping, containers, and specialty applications, with specific additives and fillers used to tailor performance.

Applications are widespread and include rigid containers (such as milk jugs and detergent bottles), piping systems for water and gas, chemical storage tanks, geomembranes, and many industrial packaging and consumer products. HDPE is favored for its strength, chemical resistance, and durability, though it can be susceptible to UV degradation if not stabilized and may suffer from stress cracking with certain chemicals or solvents under stress.

Recycling and environmental aspects: HDPE is widely recycled and identified by resin code #2. Recycled HDPE can be remanufactured into a variety of products, including pipes, containers, and automotive parts. It is non-biodegradable, and recycling efforts focus on reducing waste and conserving resources through mechanical recycling and proper collection streams.