PEHD

PEHD, short for polyéthylène haute densité (high-density polyethylene, HDPE), is a widely used thermoplastic polymer produced from ethylene by catalytic polymerization. It is valued for a relatively linear chain structure, higher density and crystallinity than other polyethylenes, which impart stiffness and strength to the material.

Typical properties include a density of about 0.941–0.965 g/cm3 and a melting point of roughly 120–130°C. HDPE exhibits good chemical resistance to many acids, bases, and hydrocarbons, has low moisture absorption, and offers high impact strength and stiffness at room temperature. It can be enhanced with stabilizers and additives for UV resistance, color, or improved performance in specific environments.

Production and processing of PEHD involve polymerizing ethylene using catalysts such as Ziegler–Natta or metallocene systems. The polymerization can occur in gas-phase, slurry, or solution processes, producing a range of grades with differing molecular weight and morphology. The resulting material is commonly used in rigid, dense forms rather than flexible films.

Applications of PEHD are broad and include piping and fittings for water and gas distribution, containers and bottles, crates, toys, geomembranes for landfills and water containment, and electrical conduits. Its rigidity, chemical resistance, and durability make it a preferred choice for outdoor and load-bearing applications.

Recycling and environmental aspects: PEHD is recyclable, typically identified by resin code 2. Recycled HDPE can be reprocessed into new containers, pipes, or other products, though properties may vary with recycling conditions. HDPE is contrasted with low-density polyethylene (LDPE), which is more flexible due to branched chains.