Inspection of Aging and Defects of Polyethylene Pipe Joints Based on THz-TDS

Herein, the aging and common defects of polyethylene (PE) pipe joints are inspected based on terahertz time-domain spectroscopy (THz-TDS). The reflective indices and absorption coefficients of PE specimens with different aging time arc calculated, and the imaging detection for the typical defects of pipe joints is conducted. It is found that the reflective indices of the PE specimens have no obvious change in 0.2-2.0 THz range after aging for a long time. However, the absorption coefficient shows a decreasing tendency with increasing aging time. Finally, the defects arc imaged using reflective THz-TDS. Pixels around the defect areas arc different from those around nondefect areas in THz images, and the defect position and outline arc revealed in the THz images.