HDPE High Density Polyethylene

The high density polyethylene and polypropylene are in many ways similar for chemical applications. A considerably improved mechanical property is obtained by the use of these materials, and the chemical resistance is also greatly increased. Only strong oxidants will attack the materials appreciably within the appropriate temperature range. Stress cracking of the HDPE can again be a problem if proper selection of the resin is not made. The better mechanical properties of these two products extend their use into larger shapes, the application of the sheet materials on the interior of appropriately designed vessels, as packing in columns, and as solid containers to compete with glass and steel.

The modulus of the polypropylene is somewhat higher, which is beneficial in certain instances. The coefficient of thermal expansion is less for polypropylene than for the high density polyethylene. Fusion welding with a hot nitrogen gun is practical in the field for both materials when the technique is learned.