The following samples have been used for welding experiments, for structure analysis, and for investigations of mechanical and thermal properties: polyethylene pipes produced from two types of high-density polyethylene (HDPE) with different minimum required strengths (MRS)—PE-80 (MWbimodal 300000 g/mol, density 0.953 g/cm3, MRS = 8 MPa), and PE-100 (MWbimodal300000 g/mol and density 0.960 g/cm3, MRS = 10 MPa).
The welding experiments have been carried out with 63 mm diameter and 6 mm wall thickness of PE-80 and PE-100 pipes using traditional hot plate butt welding under the following conditions: 200°C welding temperature, 0.2 MPa welding pressure, and 60 s upset time. Change over time was 3 s. The cooling time under pressure was 6 min. SAT-1 hot plate butt welding device produced by Experimental Welding Equipment Factory of E.O.Paton Electric Welding Institute of the NAS of Ukraine has been used for welding. Photo of PE-80 and PE-100 pipes’ weld is presented in Figure 1.