NON-DESTRUCTIVE EVALUATION FOR CRYSTALLINITY AND MOISTURE CONTENT OF POLYETHYLENE TEREPHTHALATE USING TERAHERTZ WAVE

Abstract

In this study, a terahertz time-domain spectroscopy (THz-TDS) system was used to analyze the crystallinity and moisture content of polyethylene terephthalate (PET). The crystallinity of the PET specimen was analyzed by differential scanning calorimetry (DSC), and the moisture content of the PET specimen was measured by an electronic scale. The complex refractive index with respect to the crystallinity and moisture content of the PET was obtained using the transmission mode of the THz-TDS system. As the crystallinity of the PET increased, the refractive index was increased due to the increased polymer density. In addition, as the moisture content of the PET increased, the refractive index increased since the moisture absorbed the THz signal. Consequently, it was confirmed that the crystallinity and moisture content of the PET can be successfully analyzed by THz signals.