A significant enhance of impact strength with thermal annealing in high density polyethylene

Different structural, thermal, mechanical and viscoelastic characteristics established in an annealed commercial high density polyethylene (HDPE) are described and compared to those in the as molded sample. The main features found in the annealed specimen are a significant improvement in the impact strength and a greater intensity of the p relaxation process. In addition, a loss of some low molecular weight products is also found joined to a slig ht perfection in the crystalline phase. The causes for those features are d iscussed.