Polyethylene is a thermoplastic polymer consisting of long chains produced by combining the ingredient monomer ethylene. The ethylene actually converts to ethane as it takes its place in a polymer and straight sections of the polymer are the same structure as the simple chain hydrocarbons, e.g., propane, decane and other straight single-bonded carbon chains. As with any polymer, the structure of the resulting substance defies molecular description due to cross branching of the chains. HDPE (High Density polyethylene) is defined by a density of greater or equal to 0.941 g/cm3. HDPE has a low degree of branching and stronger intermolecular forces and tensile strength.