What is High-Density Polyethylene (HDPE)? High-Density Polyethylene (HDPE) is a robust thermoplastic polymer derived from petroleum, renowned for its exceptional strength-to-density ratio. Widely used in manufacturing plastic bottles, pipes, containers, and industrial components, HDPE’s tightly packed linear molecular structure ensures superior durability, impact resistance, and moisture impermeability. As a #2 recyclable plastic, High-Density Polyethylene is