Apr 24, 2022 · hdpe plastic sheet 1/2 inch recycled plastic sheet hdpe High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a polyethylene thermoplastic made from petroleum.HDPE is defined by a density of greater or equal to 0.941 g/cm3. hdpe plastic sheet hdpe plate hdpe sheet hdpe board has a low degree of branching and thus low intermolecular forces and tensile strength.