High-density polyethylene (HDPE) is a polyethylene thermoplastic made from petroleum.
The mass density of high-density polyethylene can range from 0.93 to 0.97 g/cm³. Although the density of HDPE is only slightly higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular forces and tensile strength than LDPE. The differentiation in strength exceeds the difference in density, giving HDPE a higher specific strength. Also it is harder and more opaque and can withstand to some extent higher temperatures (120ºC/ 248ºF for short periods, 110ºC/ 230ºF continuously). High-density polyethylene, unlike polypropylene, cannot withstand normally required autoclaving conditions.